Evaluation of Acoustic Doppler Current Profiler measurements of river discharge

USGS Publications Warehouse

Morlock, S.E.

1996-01-01

The standard deviations of the ADCP measurements ranged from approximately 1 to 6 percent and were generally higher than the measurement errors predicted by error-propagation analysis of ADCP instrument performance. These error-prediction methods assume that the largest component of ADCP discharge measurement error is instrument related. The larger standard deviations indicate that substantial portions of measurement error may be attributable to sources unrelated to ADCP electronics or signal processing and are functions of the field environment.

A Comparison of Three Methods for Computing Scale Score Conditional Standard Errors of Measurement. ACT Research Report Series, 2013 (7)

ERIC Educational Resources Information Center

Woodruff, David; Traynor, Anne; Cui, Zhongmin; Fang, Yu

2013-01-01

Professional standards for educational testing recommend that both the overall standard error of measurement and the conditional standard error of measurement (CSEM) be computed on the score scale used to report scores to examinees. Several methods have been developed to compute scale score CSEMs. This paper compares three methods, based on…

Implementing parallel spreadsheet models for health policy decisions: The impact of unintentional errors on model projections

PubMed Central

Bailey, Stephanie L.; Bono, Rose S.; Nash, Denis; Kimmel, April D.

2018-01-01

Background Spreadsheet software is increasingly used to implement systems science models informing health policy decisions, both in academia and in practice where technical capacity may be limited. However, spreadsheet models are prone to unintentional errors that may not always be identified using standard error-checking techniques. Our objective was to illustrate, through a methodologic case study analysis, the impact of unintentional errors on model projections by implementing parallel model versions. Methods We leveraged a real-world need to revise an existing spreadsheet model designed to inform HIV policy. We developed three parallel versions of a previously validated spreadsheet-based model; versions differed by the spreadsheet cell-referencing approach (named single cells; column/row references; named matrices). For each version, we implemented three model revisions (re-entry into care; guideline-concordant treatment initiation; immediate treatment initiation). After standard error-checking, we identified unintentional errors by comparing model output across the three versions. Concordant model output across all versions was considered error-free. We calculated the impact of unintentional errors as the percentage difference in model projections between model versions with and without unintentional errors, using +/-5% difference to define a material error. Results We identified 58 original and 4,331 propagated unintentional errors across all model versions and revisions. Over 40% (24/58) of original unintentional errors occurred in the column/row reference model version; most (23/24) were due to incorrect cell references. Overall, >20% of model spreadsheet cells had material unintentional errors. When examining error impact along the HIV care continuum, the percentage difference between versions with and without unintentional errors ranged from +3% to +16% (named single cells), +26% to +76% (column/row reference), and 0% (named matrices). Conclusions Standard error-checking techniques may not identify all errors in spreadsheet-based models. Comparing parallel model versions can aid in identifying unintentional errors and promoting reliable model projections, particularly when resources are limited. PMID:29570737

Implementing parallel spreadsheet models for health policy decisions: The impact of unintentional errors on model projections.

PubMed

Bailey, Stephanie L; Bono, Rose S; Nash, Denis; Kimmel, April D

2018-01-01

Spreadsheet software is increasingly used to implement systems science models informing health policy decisions, both in academia and in practice where technical capacity may be limited. However, spreadsheet models are prone to unintentional errors that may not always be identified using standard error-checking techniques. Our objective was to illustrate, through a methodologic case study analysis, the impact of unintentional errors on model projections by implementing parallel model versions. We leveraged a real-world need to revise an existing spreadsheet model designed to inform HIV policy. We developed three parallel versions of a previously validated spreadsheet-based model; versions differed by the spreadsheet cell-referencing approach (named single cells; column/row references; named matrices). For each version, we implemented three model revisions (re-entry into care; guideline-concordant treatment initiation; immediate treatment initiation). After standard error-checking, we identified unintentional errors by comparing model output across the three versions. Concordant model output across all versions was considered error-free. We calculated the impact of unintentional errors as the percentage difference in model projections between model versions with and without unintentional errors, using +/-5% difference to define a material error. We identified 58 original and 4,331 propagated unintentional errors across all model versions and revisions. Over 40% (24/58) of original unintentional errors occurred in the column/row reference model version; most (23/24) were due to incorrect cell references. Overall, >20% of model spreadsheet cells had material unintentional errors. When examining error impact along the HIV care continuum, the percentage difference between versions with and without unintentional errors ranged from +3% to +16% (named single cells), +26% to +76% (column/row reference), and 0% (named matrices). Standard error-checking techniques may not identify all errors in spreadsheet-based models. Comparing parallel model versions can aid in identifying unintentional errors and promoting reliable model projections, particularly when resources are limited.

Research on Standard Errors of Equating Differences. Research Report. ETS RR-10-25

ERIC Educational Resources Information Center

Moses, Tim; Zhang, Wenmin

2010-01-01

In this paper, the "standard error of equating difference" (SEED) is described in terms of originally proposed kernel equating functions (von Davier, Holland, & Thayer, 2004) and extended to incorporate traditional linear and equipercentile functions. These derivations expand on prior developments of SEEDs and standard errors of equating and…

Automatic Error Analysis Using Intervals

ERIC Educational Resources Information Center

Rothwell, E. J.; Cloud, M. J.

2012-01-01

A technique for automatic error analysis using interval mathematics is introduced. A comparison to standard error propagation methods shows that in cases involving complicated formulas, the interval approach gives comparable error estimates with much less effort. Several examples are considered, and numerical errors are computed using the INTLAB…

Prepopulated radiology report templates: a prospective analysis of error rate and turnaround time.

PubMed

Hawkins, C M; Hall, S; Hardin, J; Salisbury, S; Towbin, A J

2012-08-01

Current speech recognition software allows exam-specific standard reports to be prepopulated into the dictation field based on the radiology information system procedure code. While it is thought that prepopulating reports can decrease the time required to dictate a study and the overall number of errors in the final report, this hypothesis has not been studied in a clinical setting. A prospective study was performed. During the first week, radiologists dictated all studies using prepopulated standard reports. During the second week, all studies were dictated after prepopulated reports had been disabled. Final radiology reports were evaluated for 11 different types of errors. Each error within a report was classified individually. The median time required to dictate an exam was compared between the 2 weeks. There were 12,387 reports dictated during the study, of which, 1,173 randomly distributed reports were analyzed for errors. There was no difference in the number of errors per report between the 2 weeks; however, radiologists overwhelmingly preferred using a standard report both weeks. Grammatical errors were by far the most common error type, followed by missense errors and errors of omission. There was no significant difference in the median dictation time when comparing studies performed each week. The use of prepopulated reports does not alone affect the error rate or dictation time of radiology reports. While it is a useful feature for radiologists, it must be coupled with other strategies in order to decrease errors.

Standard Errors of Equating for the Percentile Rank-Based Equipercentile Equating with Log-Linear Presmoothing

ERIC Educational Resources Information Center

Wang, Tianyou

2009-01-01

Holland and colleagues derived a formula for analytical standard error of equating using the delta-method for the kernel equating method. Extending their derivation, this article derives an analytical standard error of equating procedure for the conventional percentile rank-based equipercentile equating with log-linear smoothing. This procedure is…

49 CFR Appendix F to Part 240 - Medical Standards Guidelines

Code of Federal Regulations, 2010 CFR

2010-10-01

... greater guidance on the procedures that should be employed in administering the vision and hearing... more errors on plates 1-15. MULTIFUNCTION VISION TESTER Keystone Orthoscope Any error. OPTEC 2000 Any error. Titmus Vision Tester Any error. Titmus II Vision Tester Any error. (3) In administering any of...

49 CFR Appendix F to Part 240 - Medical Standards Guidelines

Code of Federal Regulations, 2011 CFR

2011-10-01

... greater guidance on the procedures that should be employed in administering the vision and hearing... more errors on plates 1-15. MULTIFUNCTION VISION TESTER Keystone Orthoscope Any error. OPTEC 2000 Any error. Titmus Vision Tester Any error. Titmus II Vision Tester Any error. (3) In administering any of...

Performance monitoring and error significance in patients with obsessive-compulsive disorder.

PubMed

Endrass, Tanja; Schuermann, Beate; Kaufmann, Christan; Spielberg, Rüdiger; Kniesche, Rainer; Kathmann, Norbert

2010-05-01

Performance monitoring has been consistently found to be overactive in obsessive-compulsive disorder (OCD). The present study examines whether performance monitoring in OCD is adjusted with error significance. Therefore, errors in a flanker task were followed by neutral (standard condition) or punishment feedbacks (punishment condition). In the standard condition patients had significantly larger error-related negativity (ERN) and correct-related negativity (CRN) ampliudes than controls. But, in the punishment condition groups did not differ in ERN and CRN amplitudes. While healthy controls showed an amplitude enhancement between standard and punishment condition, OCD patients showed no variation. In contrast, group differences were not found for the error positivity (Pe): both groups had larger Pe amplitudes in the punishment condition. Results confirm earlier findings of overactive error monitoring in OCD. The absence of a variation with error significance might indicate that OCD patients are unable to down-regulate their monitoring activity according to external requirements. Copyright 2010 Elsevier B.V. All rights reserved.

Use of a non-linear method for including the mass uncertainty of gravimetric standards and system measurement errors in the fitting of calibration curves for XRFA freeze-dried UNO/sub 3/ standards

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pickles, W.L.; McClure, J.W.; Howell, R.H.

1978-05-01

A sophisticated nonlinear multiparameter fitting program was used to produce a best fit calibration curve for the response of an x-ray fluorescence analyzer to uranium nitrate, freeze dried, 0.2% accurate, gravimetric standards. The program is based on unconstrained minimization subroutine, VA02A. The program considers the mass values of the gravimetric standards as parameters to be fit along with the normal calibration curve parameters. The fitting procedure weights with the system errors and the mass errors in a consistent way. The resulting best fit calibration curve parameters reflect the fact that the masses of the standard samples are measured quantities withmore » a known error. Error estimates for the calibration curve parameters can be obtained from the curvature of the ''Chi-Squared Matrix'' or from error relaxation techniques. It was shown that nondispersive XRFA of 0.1 to 1 mg freeze-dried UNO/sub 3/ can have an accuracy of 0.2% in 1000 s.« less

Intravenous Chemotherapy Compounding Errors in a Follow-Up Pan-Canadian Observational Study.

PubMed

Gilbert, Rachel E; Kozak, Melissa C; Dobish, Roxanne B; Bourrier, Venetia C; Koke, Paul M; Kukreti, Vishal; Logan, Heather A; Easty, Anthony C; Trbovich, Patricia L

2018-05-01

Intravenous (IV) compounding safety has garnered recent attention as a result of high-profile incidents, awareness efforts from the safety community, and increasingly stringent practice standards. New research with more-sensitive error detection techniques continues to reinforce that error rates with manual IV compounding are unacceptably high. In 2014, our team published an observational study that described three types of previously unrecognized and potentially catastrophic latent chemotherapy preparation errors in Canadian oncology pharmacies that would otherwise be undetectable. We expand on this research and explore whether additional potential human failures are yet to be addressed by practice standards. Field observations were conducted in four cancer center pharmacies in four Canadian provinces from January 2013 to February 2015. Human factors specialists observed and interviewed pharmacy managers, oncology pharmacists, pharmacy technicians, and pharmacy assistants as they carried out their work. Emphasis was on latent errors (potential human failures) that could lead to outcomes such as wrong drug, dose, or diluent. Given the relatively short observational period, no active failures or actual errors were observed. However, 11 latent errors in chemotherapy compounding were identified. In terms of severity, all 11 errors create the potential for a patient to receive the wrong drug or dose, which in the context of cancer care, could lead to death or permanent loss of function. Three of the 11 practices were observed in our previous study, but eight were new. Applicable Canadian and international standards and guidelines do not explicitly address many of the potentially error-prone practices observed. We observed a significant degree of risk for error in manual mixing practice. These latent errors may exist in other regions where manual compounding of IV chemotherapy takes place. Continued efforts to advance standards, guidelines, technological innovation, and chemical quality testing are needed.

Conditional Standard Errors, Reliability and Decision Consistency of Performance Levels Using Polytomous IRT.

ERIC Educational Resources Information Center

Wang, Tianyou; And Others

M. J. Kolen, B. A. Hanson, and R. L. Brennan (1992) presented a procedure for assessing the conditional standard error of measurement (CSEM) of scale scores using a strong true-score model. They also investigated the ways of using nonlinear transformation from number-correct raw score to scale score to equalize the conditional standard error along…

Role-modeling and medical error disclosure: a national survey of trainees.

PubMed

Martinez, William; Hickson, Gerald B; Miller, Bonnie M; Doukas, David J; Buckley, John D; Song, John; Sehgal, Niraj L; Deitz, Jennifer; Braddock, Clarence H; Lehmann, Lisa Soleymani

2014-03-01

To measure trainees' exposure to negative and positive role-modeling for responding to medical errors and to examine the association between that exposure and trainees' attitudes and behaviors regarding error disclosure. Between May 2011 and June 2012, 435 residents at two large academic medical centers and 1,187 medical students from seven U.S. medical schools received anonymous, electronic questionnaires. The questionnaire asked respondents about (1) experiences with errors, (2) training for responding to errors, (3) behaviors related to error disclosure, (4) exposure to role-modeling for responding to errors, and (5) attitudes regarding disclosure. Using multivariate regression, the authors analyzed whether frequency of exposure to negative and positive role-modeling independently predicted two primary outcomes: (1) attitudes regarding disclosure and (2) nontransparent behavior in response to a harmful error. The response rate was 55% (884/1,622). Training on how to respond to errors had the largest independent, positive effect on attitudes (standardized effect estimate, 0.32, P < .001); negative role-modeling had the largest independent, negative effect (standardized effect estimate, -0.26, P < .001). Positive role-modeling had a positive effect on attitudes (standardized effect estimate, 0.26, P < .001). Exposure to negative role-modeling was independently associated with an increased likelihood of trainees' nontransparent behavior in response to an error (OR 1.37, 95% CI 1.15-1.64; P < .001). Exposure to role-modeling predicts trainees' attitudes and behavior regarding the disclosure of harmful errors. Negative role models may be a significant impediment to disclosure among trainees.

Is Comprehension Necessary for Error Detection? A Conflict-Based Account of Monitoring in Speech Production

ERIC Educational Resources Information Center

Nozari, Nazbanou; Dell, Gary S.; Schwartz, Myrna F.

2011-01-01

Despite the existence of speech errors, verbal communication is successful because speakers can detect (and correct) their errors. The standard theory of speech-error detection, the perceptual-loop account, posits that the comprehension system monitors production output for errors. Such a comprehension-based monitor, however, cannot explain the…

Evaluation of lens distortion errors in video-based motion analysis

NASA Technical Reports Server (NTRS)

Poliner, Jeffrey; Wilmington, Robert; Klute, Glenn K.; Micocci, Angelo

1993-01-01

In an effort to study lens distortion errors, a grid of points of known dimensions was constructed and videotaped using a standard and a wide-angle lens. Recorded images were played back on a VCR and stored on a personal computer. Using these stored images, two experiments were conducted. Errors were calculated as the difference in distance from the known coordinates of the points to the calculated coordinates. The purposes of this project were as follows: (1) to develop the methodology to evaluate errors introduced by lens distortion; (2) to quantify and compare errors introduced by use of both a 'standard' and a wide-angle lens; (3) to investigate techniques to minimize lens-induced errors; and (4) to determine the most effective use of calibration points when using a wide-angle lens with a significant amount of distortion. It was seen that when using a wide-angle lens, errors from lens distortion could be as high as 10 percent of the size of the entire field of view. Even with a standard lens, there was a small amount of lens distortion. It was also found that the choice of calibration points influenced the lens distortion error. By properly selecting the calibration points and avoidance of the outermost regions of a wide-angle lens, the error from lens distortion can be kept below approximately 0.5 percent with a standard lens and 1.5 percent with a wide-angle lens.

Error estimation of deformable image registration of pulmonary CT scans using convolutional neural networks.

PubMed

Eppenhof, Koen A J; Pluim, Josien P W

2018-04-01

Error estimation in nonlinear medical image registration is a nontrivial problem that is important for validation of registration methods. We propose a supervised method for estimation of registration errors in nonlinear registration of three-dimensional (3-D) images. The method is based on a 3-D convolutional neural network that learns to estimate registration errors from a pair of image patches. By applying the network to patches centered around every voxel, we construct registration error maps. The network is trained using a set of representative images that have been synthetically transformed to construct a set of image pairs with known deformations. The method is evaluated on deformable registrations of inhale-exhale pairs of thoracic CT scans. Using ground truth target registration errors on manually annotated landmarks, we evaluate the method's ability to estimate local registration errors. Estimation of full domain error maps is evaluated using a gold standard approach. The two evaluation approaches show that we can train the network to robustly estimate registration errors in a predetermined range, with subvoxel accuracy. We achieved a root-mean-square deviation of 0.51 mm from gold standard registration errors and of 0.66 mm from ground truth landmark registration errors.

Medical students' experiences with medical errors: an analysis of medical student essays.

PubMed

Martinez, William; Lo, Bernard

2008-07-01

This study aimed to examine medical students' experiences with medical errors. In 2001 and 2002, 172 fourth-year medical students wrote an anonymous description of a significant medical error they had witnessed or committed during their clinical clerkships. The assignment represented part of a required medical ethics course. We analysed 147 of these essays using thematic content analysis. Many medical students made or observed significant errors. In either situation, some students experienced distress that seemingly went unaddressed. Furthermore, this distress was sometimes severe and persisted after the initial event. Some students also experienced considerable uncertainty as to whether an error had occurred and how to prevent future errors. Many errors may not have been disclosed to patients, and some students who desired to discuss or disclose errors were apparently discouraged from doing so by senior doctors. Some students criticised senior doctors who attempted to hide errors or avoid responsibility. By contrast, students who witnessed senior doctors take responsibility for errors and candidly disclose errors to patients appeared to recognise the importance of honesty and integrity and said they aspired to these standards. There are many missed opportunities to teach students how to respond to and learn from errors. Some faculty members and housestaff may at times respond to errors in ways that appear to contradict professional standards. Medical educators should increase exposure to exemplary responses to errors and help students to learn from and cope with errors.

Increasing point-count duration increases standard error

USGS Publications Warehouse

Smith, W.P.; Twedt, D.J.; Hamel, P.B.; Ford, R.P.; Wiedenfeld, D.A.; Cooper, R.J.

1998-01-01

We examined data from point counts of varying duration in bottomland forests of west Tennessee and the Mississippi Alluvial Valley to determine if counting interval influenced sampling efficiency. Estimates of standard error increased as point count duration increased both for cumulative number of individuals and species in both locations. Although point counts appear to yield data with standard errors proportional to means, a square root transformation of the data may stabilize the variance. Using long (>10 min) point counts may reduce sample size and increase sampling error, both of which diminish statistical power and thereby the ability to detect meaningful changes in avian populations.

Estimating standard errors in feature network models.

PubMed

Frank, Laurence E; Heiser, Willem J

2007-05-01

Feature network models are graphical structures that represent proximity data in a discrete space while using the same formalism that is the basis of least squares methods employed in multidimensional scaling. Existing methods to derive a network model from empirical data only give the best-fitting network and yield no standard errors for the parameter estimates. The additivity properties of networks make it possible to consider the model as a univariate (multiple) linear regression problem with positivity restrictions on the parameters. In the present study, both theoretical and empirical standard errors are obtained for the constrained regression parameters of a network model with known features. The performance of both types of standard error is evaluated using Monte Carlo techniques.

When do latent class models overstate accuracy for diagnostic and other classifiers in the absence of a gold standard?

PubMed

Spencer, Bruce D

2012-06-01

Latent class models are increasingly used to assess the accuracy of medical diagnostic tests and other classifications when no gold standard is available and the true state is unknown. When the latent class is treated as the true class, the latent class models provide measures of components of accuracy including specificity and sensitivity and their complements, type I and type II error rates. The error rates according to the latent class model differ from the true error rates, however, and empirical comparisons with a gold standard suggest the true error rates often are larger. We investigate conditions under which the true type I and type II error rates are larger than those provided by the latent class models. Results from Uebersax (1988, Psychological Bulletin 104, 405-416) are extended to accommodate random effects and covariates affecting the responses. The results are important for interpreting the results of latent class analyses. An error decomposition is presented that incorporates an error component from invalidity of the latent class model. © 2011, The International Biometric Society.

Nonlinear method for including the mass uncertainty of standards and the system measurement errors in the fitting of calibration curves

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pickles, W.L.; McClure, J.W.; Howell, R.H.

1978-01-01

A sophisticated non-linear multiparameter fitting program has been used to produce a best fit calibration curve for the response of an x-ray fluorescence analyzer to uranium nitrate, freeze dried, 0.2% accurate, gravimetric standards. The program is based on unconstrained minimization subroutine, VA02A. The program considers the mass values of the gravimetric standards as parameters to be fit along with the normal calibration curve parameters. The fitting procedure weights with the system errors and the mass errors in a consistent way. The resulting best fit calibration curve parameters reflect the fact that the masses of the standard samples are measured quantitiesmore » with a known error. Error estimates for the calibration curve parameters can be obtined from the curvature of the Chi-Squared Matrix or from error relaxation techniques. It has been shown that non-dispersive x-ray fluorescence analysis of 0.1 to 1 mg freeze-dried UNO/sub 3/ can have an accuracy of 0.2% in 1000 sec.« less

Reduction of medication errors related to sliding scale insulin by the introduction of a standardized order sheet.

PubMed

Harada, Saki; Suzuki, Akio; Nishida, Shohei; Kobayashi, Ryo; Tamai, Sayuri; Kumada, Keisuke; Murakami, Nobuo; Itoh, Yoshinori

2017-06-01

Insulin is frequently used for glycemic control. Medication errors related to insulin are a common problem for medical institutions. Here, we prepared a standardized sliding scale insulin (SSI) order sheet and assessed the effect of its introduction. Observations before and after the introduction of the standardized SSI template were conducted at Gifu University Hospital. The incidence of medication errors, hyperglycemia, and hypoglycemia related to SSI were obtained from the electronic medical records. The introduction of the standardized SSI order sheet significantly reduced the incidence of medication errors related to SSI compared with that prior to its introduction (12/165 [7.3%] vs 4/159 [2.1%], P = .048). However, the incidence of hyperglycemia (≥250 mg/dL) and hypoglycemia (≤50 mg/dL) in patients who received SSI was not significantly different between the 2 groups. The introduction of the standardized SSI order sheet reduced the incidence of medication errors related to SSI. © 2016 John Wiley & Sons, Ltd.

A Criterion to Control Nonlinear Error in the Mixed-Mode Bending Test

NASA Technical Reports Server (NTRS)

Reeder, James R.

2002-01-01

The mixed-mode bending test ha: been widely used to measure delamination toughness and was recently standardized by ASTM as Standard Test Method D6671-01. This simple test is a combination of the standard Mode I (opening) test and a Mode II (sliding) test. This test uses a unidirectional composite test specimen with an artificial delamination subjected to bending loads to characterize when a delamination will extend. When the displacements become large, the linear theory used to analyze the results of the test yields errors in the calcu1ated toughness values. The current standard places no limit on the specimen loading and therefore test data can be created using the standard that are significantly in error. A method of limiting the error that can be incurred in the calculated toughness values is needed. In this paper, nonlinear models of the MMB test are refined. One of the nonlinear models is then used to develop a simple criterion for prescribing conditions where thc nonlinear error will remain below 5%.

Simplified Approach Charts Improve Data Retrieval Performance

PubMed Central

Stewart, Michael; Laraway, Sean; Jordan, Kevin; Feary, Michael S.

2016-01-01

The effectiveness of different instrument approach charts to deliver minimum visibility and altitude information during airport equipment outages was investigated. Eighteen pilots flew simulated instrument approaches in three conditions: (a) normal operations using a standard approach chart (standard-normal), (b) equipment outage conditions using a standard approach chart (standard-outage), and (c) equipment outage conditions using a prototype decluttered approach chart (prototype-outage). Errors and retrieval times in identifying minimum altitudes and visibilities were measured. The standard-outage condition produced significantly more errors and longer retrieval times versus the standard-normal condition. The prototype-outage condition had significantly fewer errors and shorter retrieval times than did the standard-outage condition. The prototype-outage condition produced significantly fewer errors but similar retrieval times when compared with the standard-normal condition. Thus, changing the presentation of minima may reduce risk and increase safety in instrument approaches, specifically with airport equipment outages. PMID:28491009

Error model for the SAO 1969 standard earth.

NASA Technical Reports Server (NTRS)

Martin, C. F.; Roy, N. A.

1972-01-01

A method is developed for estimating an error model for geopotential coefficients using satellite tracking data. A single station's apparent timing error for each pass is attributed to geopotential errors. The root sum of the residuals for each station also depends on the geopotential errors, and these are used to select an error model. The model chosen is 1/4 of the difference between the SAO M1 and the APL 3.5 geopotential.

Scaled test statistics and robust standard errors for non-normal data in covariance structure analysis: a Monte Carlo study.

PubMed

Chou, C P; Bentler, P M; Satorra, A

1991-11-01

Research studying robustness of maximum likelihood (ML) statistics in covariance structure analysis has concluded that test statistics and standard errors are biased under severe non-normality. An estimation procedure known as asymptotic distribution free (ADF), making no distributional assumption, has been suggested to avoid these biases. Corrections to the normal theory statistics to yield more adequate performance have also been proposed. This study compares the performance of a scaled test statistic and robust standard errors for two models under several non-normal conditions and also compares these with the results from ML and ADF methods. Both ML and ADF test statistics performed rather well in one model and considerably worse in the other. In general, the scaled test statistic seemed to behave better than the ML test statistic and the ADF statistic performed the worst. The robust and ADF standard errors yielded more appropriate estimates of sampling variability than the ML standard errors, which were usually downward biased, in both models under most of the non-normal conditions. ML test statistics and standard errors were found to be quite robust to the violation of the normality assumption when data had either symmetric and platykurtic distributions, or non-symmetric and zero kurtotic distributions.

The influence of different error estimates in the detection of postoperative cognitive dysfunction using reliable change indices with correction for practice effects.

PubMed

Lewis, Matthew S; Maruff, Paul; Silbert, Brendan S; Evered, Lis A; Scott, David A

2007-02-01

The reliable change index (RCI) expresses change relative to its associated error, and is useful in the identification of postoperative cognitive dysfunction (POCD). This paper examines four common RCIs that each account for error in different ways. Three rules incorporate a constant correction for practice effects and are contrasted with the standard RCI that had no correction for practice. These rules are applied to 160 patients undergoing coronary artery bypass graft (CABG) surgery who completed neuropsychological assessments preoperatively and 1 week postoperatively using error and reliability data from a comparable healthy nonsurgical control group. The rules all identify POCD in a similar proportion of patients, but the use of the within-subject standard deviation (WSD), expressing the effects of random error, as an error estimate is a theoretically appropriate denominator when a constant error correction, removing the effects of systematic error, is deducted from the numerator in a RCI.

New dimension analyses with error analysis for quaking aspen and black spruce

NASA Technical Reports Server (NTRS)

Woods, K. D.; Botkin, D. B.; Feiveson, A. H.

1987-01-01

Dimension analysis for black spruce in wetland stands and trembling aspen are reported, including new approaches in error analysis. Biomass estimates for sacrificed trees have standard errors of 1 to 3%; standard errors for leaf areas are 10 to 20%. Bole biomass estimation accounts for most of the error for biomass, while estimation of branch characteristics and area/weight ratios accounts for the leaf area error. Error analysis provides insight for cost effective design of future analyses. Predictive equations for biomass and leaf area, with empirically derived estimators of prediction error, are given. Systematic prediction errors for small aspen trees and for leaf area of spruce from different site-types suggest a need for different predictive models within species. Predictive equations are compared with published equations; significant differences may be due to species responses to regional or site differences. Proportional contributions of component biomass in aspen change in ways related to tree size and stand development. Spruce maintains comparatively constant proportions with size, but shows changes corresponding to site. This suggests greater morphological plasticity of aspen and significance for spruce of nutrient conditions.

The Calibration of Gloss Reference Standards

NASA Astrophysics Data System (ADS)

Budde, W.

1980-04-01

In present international and national standards for the measurement of specular gloss the primary and secondary reference standards are defined for monochromatic radiation. However the glossmeter specified is using polychromatic radiation (CIE Standard Illuminant C) and the CIE Standard Photometric Observer. This produces errors in practical gloss measurements of up to 0.5%. Although this may be considered small as compared to the accuracy of most practical gloss measurements, such an error should not be tolerated in the calibration of secondary standards. Corrections for such errors are presented and various alternatives for amendments of the existing documentary standards are discussed.

Evaluating concentration estimation errors in ELISA microarray experiments

DOE Office of Scientific and Technical Information (OSTI.GOV)

Daly, Don S.; White, Amanda M.; Varnum, Susan M.

Enzyme-linked immunosorbent assay (ELISA) is a standard immunoassay to predict a protein concentration in a sample. Deploying ELISA in a microarray format permits simultaneous prediction of the concentrations of numerous proteins in a small sample. These predictions, however, are uncertain due to processing error and biological variability. Evaluating prediction error is critical to interpreting biological significance and improving the ELISA microarray process. Evaluating prediction error must be automated to realize a reliable high-throughput ELISA microarray system. Methods: In this paper, we present a statistical method based on propagation of error to evaluate prediction errors in the ELISA microarray process. Althoughmore » propagation of error is central to this method, it is effective only when comparable data are available. Therefore, we briefly discuss the roles of experimental design, data screening, normalization and statistical diagnostics when evaluating ELISA microarray prediction errors. We use an ELISA microarray investigation of breast cancer biomarkers to illustrate the evaluation of prediction errors. The illustration begins with a description of the design and resulting data, followed by a brief discussion of data screening and normalization. In our illustration, we fit a standard curve to the screened and normalized data, review the modeling diagnostics, and apply propagation of error.« less

Improving patient safety through quality assurance.

PubMed

Raab, Stephen S

2006-05-01

Anatomic pathology laboratories use several quality assurance tools to detect errors and to improve patient safety. To review some of the anatomic pathology laboratory patient safety quality assurance practices. Different standards and measures in anatomic pathology quality assurance and patient safety were reviewed. Frequency of anatomic pathology laboratory error, variability in the use of specific quality assurance practices, and use of data for error reduction initiatives. Anatomic pathology error frequencies vary according to the detection method used. Based on secondary review, a College of American Pathologists Q-Probes study showed that the mean laboratory error frequency was 6.7%. A College of American Pathologists Q-Tracks study measuring frozen section discrepancy found that laboratories improved the longer they monitored and shared data. There is a lack of standardization across laboratories even for governmentally mandated quality assurance practices, such as cytologic-histologic correlation. The National Institutes of Health funded a consortium of laboratories to benchmark laboratory error frequencies, perform root cause analysis, and design error reduction initiatives, using quality assurance data. Based on the cytologic-histologic correlation process, these laboratories found an aggregate nongynecologic error frequency of 10.8%. Based on gynecologic error data, the laboratory at my institution used Toyota production system processes to lower gynecologic error frequencies and to improve Papanicolaou test metrics. Laboratory quality assurance practices have been used to track error rates, and laboratories are starting to use these data for error reduction initiatives.

A Note on Standard Deviation and Standard Error

ERIC Educational Resources Information Center

Hassani, Hossein; Ghodsi, Mansoureh; Howell, Gareth

2010-01-01

Many students confuse the standard deviation and standard error of the mean and are unsure which, if either, to use in presenting data. In this article, we endeavour to address these questions and cover some related ambiguities about these quantities.

Development of a simple system for simultaneously measuring 6DOF geometric motion errors of a linear guide.

PubMed

Qibo, Feng; Bin, Zhang; Cunxing, Cui; Cuifang, Kuang; Yusheng, Zhai; Fenglin, You

2013-11-04

A simple method for simultaneously measuring the 6DOF geometric motion errors of the linear guide was proposed. The mechanisms for measuring straightness and angular errors and for enhancing their resolution are described in detail. A common-path method for measuring the laser beam drift was proposed and it was used to compensate the errors produced by the laser beam drift in the 6DOF geometric error measurements. A compact 6DOF system was built. Calibration experiments with certain standard measurement meters showed that our system has a standard deviation of 0.5 µm in a range of ± 100 µm for the straightness measurements, and standard deviations of 0.5", 0.5", and 1.0" in the range of ± 100" for pitch, yaw, and roll measurements, respectively.

Errors in Bibliographic Citations: A Continuing Problem.

ERIC Educational Resources Information Center

Sweetland, James H.

1989-01-01

Summarizes studies examining citation errors and illustrates errors resulting from a lack of standardization, misunderstanding of foreign languages, failure to examine the document cited, and general lack of training in citation norms. It is argued that the failure to detect and correct citation errors is due to diffusion of responsibility in the…

The computation of equating errors in international surveys in education.

PubMed

Monseur, Christian; Berezner, Alla

2007-01-01

Since the IEA's Third International Mathematics and Science Study, one of the major objectives of international surveys in education has been to report trends in achievement. The names of the two current IEA surveys reflect this growing interest: Trends in International Mathematics and Science Study (TIMSS) and Progress in International Reading Literacy Study (PIRLS). Similarly a central concern of the OECD's PISA is with trends in outcomes over time. To facilitate trend analyses these studies link their tests using common item equating in conjunction with item response modelling methods. IEA and PISA policies differ in terms of reporting the error associated with trends. In IEA surveys, the standard errors of the trend estimates do not include the uncertainty associated with the linking step while PISA does include a linking error component in the standard errors of trend estimates. In other words, PISA implicitly acknowledges that trend estimates partly depend on the selected common items, while the IEA's surveys do not recognise this source of error. Failing to recognise the linking error leads to an underestimation of the standard errors and thus increases the Type I error rate, thereby resulting in reporting of significant changes in achievement when in fact these are not significant. The growing interest of policy makers in trend indicators and the impact of the evaluation of educational reforms appear to be incompatible with such underestimation. However, the procedure implemented by PISA raises a few issues about the underlying assumptions for the computation of the equating error. After a brief introduction, this paper will describe the procedure PISA implemented to compute the linking error. The underlying assumptions of this procedure will then be discussed. Finally an alternative method based on replication techniques will be presented, based on a simulation study and then applied to the PISA 2000 data.

Estimating extreme stream temperatures by the standard deviate method

NASA Astrophysics Data System (ADS)

Bogan, Travis; Othmer, Jonathan; Mohseni, Omid; Stefan, Heinz

2006-02-01

It is now widely accepted that global climate warming is taking place on the earth. Among many other effects, a rise in air temperatures is expected to increase stream temperatures indefinitely. However, due to evaporative cooling, stream temperatures do not increase linearly with increasing air temperatures indefinitely. Within the anticipated bounds of climate warming, extreme stream temperatures may therefore not rise substantially. With this concept in mind, past extreme temperatures measured at 720 USGS stream gauging stations were analyzed by the standard deviate method. In this method the highest stream temperatures are expressed as the mean temperature of a measured partial maximum stream temperature series plus its standard deviation multiplied by a factor KE (standard deviate). Various KE-values were explored; values of KE larger than 8 were found physically unreasonable. It is concluded that the value of KE should be in the range from 7 to 8. A unit error in estimating KE translates into a typical stream temperature error of about 0.5 °C. Using a logistic model for the stream temperature/air temperature relationship, a one degree error in air temperature gives a typical error of 0.16 °C in stream temperature. With a projected error in the enveloping standard deviate dKE=1.0 (range 0.5-1.5) and an error in projected high air temperature d Ta=2 °C (range 0-4 °C), the total projected stream temperature error is estimated as d Ts=0.8 °C.

Decreasing patient identification band errors by standardizing processes.

PubMed

Walley, Susan Chu; Berger, Stephanie; Harris, Yolanda; Gallizzi, Gina; Hayes, Leslie

2013-04-01

Patient identification (ID) bands are an essential component in patient ID. Quality improvement methodology has been applied as a model to reduce ID band errors although previous studies have not addressed standardization of ID bands. Our specific aim was to decrease ID band errors by 50% in a 12-month period. The Six Sigma DMAIC (define, measure, analyze, improve, and control) quality improvement model was the framework for this study. ID bands at a tertiary care pediatric hospital were audited from January 2011 to January 2012 with continued audits to June 2012 to confirm the new process was in control. After analysis, the major improvement strategy implemented was standardization of styles of ID bands and labels. Additional interventions included educational initiatives regarding the new ID band processes and disseminating institutional and nursing unit data. A total of 4556 ID bands were audited with a preimprovement ID band error average rate of 9.2%. Significant variation in the ID band process was observed, including styles of ID bands. Interventions were focused on standardization of the ID band and labels. The ID band error rate improved to 5.2% in 9 months (95% confidence interval: 2.5-5.5; P < .001) and was maintained for 8 months. Standardization of ID bands and labels in conjunction with other interventions resulted in a statistical decrease in ID band error rates. This decrease in ID band error rates was maintained over the subsequent 8 months.

Laboratory errors and patient safety.

PubMed

Miligy, Dawlat A

2015-01-01

Laboratory data are extensively used in medical practice; consequently, laboratory errors have a tremendous impact on patient safety. Therefore, programs designed to identify and reduce laboratory errors, as well as, setting specific strategies are required to minimize these errors and improve patient safety. The purpose of this paper is to identify part of the commonly encountered laboratory errors throughout our practice in laboratory work, their hazards on patient health care and some measures and recommendations to minimize or to eliminate these errors. Recording the encountered laboratory errors during May 2008 and their statistical evaluation (using simple percent distribution) have been done in the department of laboratory of one of the private hospitals in Egypt. Errors have been classified according to the laboratory phases and according to their implication on patient health. Data obtained out of 1,600 testing procedure revealed that the total number of encountered errors is 14 tests (0.87 percent of total testing procedures). Most of the encountered errors lay in the pre- and post-analytic phases of testing cycle (representing 35.7 and 50 percent, respectively, of total errors). While the number of test errors encountered in the analytic phase represented only 14.3 percent of total errors. About 85.7 percent of total errors were of non-significant implication on patients health being detected before test reports have been submitted to the patients. On the other hand, the number of test errors that have been already submitted to patients and reach the physician represented 14.3 percent of total errors. Only 7.1 percent of the errors could have an impact on patient diagnosis. The findings of this study were concomitant with those published from the USA and other countries. This proves that laboratory problems are universal and need general standardization and bench marking measures. Original being the first data published from Arabic countries that evaluated the encountered laboratory errors and launch the great need for universal standardization and bench marking measures to control the laboratory work.

Bootstrap Standard Errors for Maximum Likelihood Ability Estimates When Item Parameters Are Unknown

ERIC Educational Resources Information Center

Patton, Jeffrey M.; Cheng, Ying; Yuan, Ke-Hai; Diao, Qi

2014-01-01

When item parameter estimates are used to estimate the ability parameter in item response models, the standard error (SE) of the ability estimate must be corrected to reflect the error carried over from item calibration. For maximum likelihood (ML) ability estimates, a corrected asymptotic SE is available, but it requires a long test and the…

Defining the Relationship Between Human Error Classes and Technology Intervention Strategies

NASA Technical Reports Server (NTRS)

Wiegmann, Douglas A.; Rantanen, Esa; Crisp, Vicki K. (Technical Monitor)

2002-01-01

One of the main factors in all aviation accidents is human error. The NASA Aviation Safety Program (AvSP), therefore, has identified several human-factors safety technologies to address this issue. Some technologies directly address human error either by attempting to reduce the occurrence of errors or by mitigating the negative consequences of errors. However, new technologies and system changes may also introduce new error opportunities or even induce different types of errors. Consequently, a thorough understanding of the relationship between error classes and technology "fixes" is crucial for the evaluation of intervention strategies outlined in the AvSP, so that resources can be effectively directed to maximize the benefit to flight safety. The purpose of the present project, therefore, was to examine the repositories of human factors data to identify the possible relationship between different error class and technology intervention strategies. The first phase of the project, which is summarized here, involved the development of prototype data structures or matrices that map errors onto "fixes" (and vice versa), with the hope of facilitating the development of standards for evaluating safety products. Possible follow-on phases of this project are also discussed. These additional efforts include a thorough and detailed review of the literature to fill in the data matrix and the construction of a complete database and standards checklists.

Evaluating a medical error taxonomy.

PubMed

Brixey, Juliana; Johnson, Todd R; Zhang, Jiajie

2002-01-01

Healthcare has been slow in using human factors principles to reduce medical errors. The Center for Devices and Radiological Health (CDRH) recognizes that a lack of attention to human factors during product development may lead to errors that have the potential for patient injury, or even death. In response to the need for reducing medication errors, the National Coordinating Council for Medication Errors Reporting and Prevention (NCC MERP) released the NCC MERP taxonomy that provides a standard language for reporting medication errors. This project maps the NCC MERP taxonomy of medication error to MedWatch medical errors involving infusion pumps. Of particular interest are human factors associated with medical device errors. The NCC MERP taxonomy of medication errors is limited in mapping information from MEDWATCH because of the focus on the medical device and the format of reporting.

A comparison of registration errors with imageless computer navigation during MIS total knee arthroplasty versus standard incision total knee arthroplasty: a cadaveric study.

PubMed

Davis, Edward T; Pagkalos, Joseph; Gallie, Price A M; Macgroarty, Kelly; Waddell, James P; Schemitsch, Emil H

2015-01-01

Optimal component alignment in total knee arthroplasty has been associated with better functional outcome as well as improved implant longevity. The ability to align components optimally during minimally invasive (MIS) total knee replacement (TKR) has been a cause of concern. Computer navigation is a useful aid in achieving the desired alignment although it is limited by the error during the manual registration of landmarks. Our study aims to compare the registration process error between a standard and a MIS surgical approach. We hypothesized that performing the registration error via an MIS approach would increase the registration process error. Five fresh frozen lower limbs were routinely prepared and draped. The registration process was performed through an MIS approach. This was then extended to the standard approach and the registration was performed again. Two surgeons performed the registration process five times with each approach. Performing the registration process through the MIS approach was not associated with higher error compared to the standard approach in the alignment parameters of interest. This rejects our hypothesis. Image-free navigated MIS TKR does not appear to carry higher risk of component malalignment due to the registration process error. Navigation can be used during MIS TKR to improve alignment without reduced accuracy due to the approach.

Frequency of data extraction errors and methods to increase data extraction quality: a methodological review.

PubMed

Mathes, Tim; Klaßen, Pauline; Pieper, Dawid

2017-11-28

Our objective was to assess the frequency of data extraction errors and its potential impact on results in systematic reviews. Furthermore, we evaluated the effect of different extraction methods, reviewer characteristics and reviewer training on error rates and results. We performed a systematic review of methodological literature in PubMed, Cochrane methodological registry, and by manual searches (12/2016). Studies were selected by two reviewers independently. Data were extracted in standardized tables by one reviewer and verified by a second. The analysis included six studies; four studies on extraction error frequency, one study comparing different reviewer extraction methods and two studies comparing different reviewer characteristics. We did not find a study on reviewer training. There was a high rate of extraction errors (up to 50%). Errors often had an influence on effect estimates. Different data extraction methods and reviewer characteristics had moderate effect on extraction error rates and effect estimates. The evidence base for established standards of data extraction seems weak despite the high prevalence of extraction errors. More comparative studies are needed to get deeper insights into the influence of different extraction methods.

Defining the Relationship Between Human Error Classes and Technology Intervention Strategies

NASA Technical Reports Server (NTRS)

Wiegmann, Douglas A.; Rantanen, Eas M.

2003-01-01

The modus operandi in addressing human error in aviation systems is predominantly that of technological interventions or fixes. Such interventions exhibit considerable variability both in terms of sophistication and application. Some technological interventions address human error directly while others do so only indirectly. Some attempt to eliminate the occurrence of errors altogether whereas others look to reduce the negative consequences of these errors. In any case, technological interventions add to the complexity of the systems and may interact with other system components in unforeseeable ways and often create opportunities for novel human errors. Consequently, there is a need to develop standards for evaluating the potential safety benefit of each of these intervention products so that resources can be effectively invested to produce the biggest benefit to flight safety as well as to mitigate any adverse ramifications. The purpose of this project was to help define the relationship between human error and technological interventions, with the ultimate goal of developing a set of standards for evaluating or measuring the potential benefits of new human error fixes.

Random errors in interferometry with the least-squares method

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang Qi

2011-01-20

This investigation analyzes random errors in interferometric surface profilers using the least-squares method when random noises are present. Two types of random noise are considered here: intensity noise and position noise. Two formulas have been derived for estimating the standard deviations of the surface height measurements: one is for estimating the standard deviation when only intensity noise is present, and the other is for estimating the standard deviation when only position noise is present. Measurements on simulated noisy interferometric data have been performed, and standard deviations of the simulated measurements have been compared with those theoretically derived. The relationships havemore » also been discussed between random error and the wavelength of the light source and between random error and the amplitude of the interference fringe.« less

Ensemble-type numerical uncertainty information from single model integrations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rauser, Florian, E-mail: florian.rauser@mpimet.mpg.de; Marotzke, Jochem; Korn, Peter

2015-07-01

We suggest an algorithm that quantifies the discretization error of time-dependent physical quantities of interest (goals) for numerical models of geophysical fluid dynamics. The goal discretization error is estimated using a sum of weighted local discretization errors. The key feature of our algorithm is that these local discretization errors are interpreted as realizations of a random process. The random process is determined by the model and the flow state. From a class of local error random processes we select a suitable specific random process by integrating the model over a short time interval at different resolutions. The weights of themore » influences of the local discretization errors on the goal are modeled as goal sensitivities, which are calculated via automatic differentiation. The integration of the weighted realizations of local error random processes yields a posterior ensemble of goal approximations from a single run of the numerical model. From the posterior ensemble we derive the uncertainty information of the goal discretization error. This algorithm bypasses the requirement of detailed knowledge about the models discretization to generate numerical error estimates. The algorithm is evaluated for the spherical shallow-water equations. For two standard test cases we successfully estimate the error of regional potential energy, track its evolution, and compare it to standard ensemble techniques. The posterior ensemble shares linear-error-growth properties with ensembles of multiple model integrations when comparably perturbed. The posterior ensemble numerical error estimates are of comparable size as those of a stochastic physics ensemble.« less

Derivation of an analytic expression for the error associated with the noise reduction rating

NASA Astrophysics Data System (ADS)

Murphy, William J.

2005-04-01

Hearing protection devices are assessed using the Real Ear Attenuation at Threshold (REAT) measurement procedure for the purpose of estimating the amount of noise reduction provided when worn by a subject. The rating number provided on the protector label is a function of the mean and standard deviation of the REAT results achieved by the test subjects. If a group of subjects have a large variance, then it follows that the certainty of the rating should be correspondingly lower. No estimate of the error of a protector's rating is given by existing standards or regulations. Propagation of errors was applied to the Noise Reduction Rating to develop an analytic expression for the hearing protector rating error term. Comparison of the analytic expression for the error to the standard deviation estimated from Monte Carlo simulation of subject attenuations yielded a linear relationship across several protector types and assumptions for the variance of the attenuations.

Total ozone trend significance from space time variability of daily Dobson data

NASA Technical Reports Server (NTRS)

Wilcox, R. W.

1981-01-01

Estimates of standard errors of total ozone time and area means, as derived from ozone's natural temporal and spatial variability and autocorrelation in middle latitudes determined from daily Dobson data are presented. Assessing the significance of apparent total ozone trends is equivalent to assessing the standard error of the means. Standard errors of time averages depend on the temporal variability and correlation of the averaged parameter. Trend detectability is discussed, both for the present network and for satellite measurements.

Analysis of DGPS/INS and MLS/INS final approach navigation errors and control performance data

NASA Technical Reports Server (NTRS)

Hueschen, Richard M.; Spitzer, Cary R.

1992-01-01

Flight tests were conducted jointly by NASA Langley Research Center and Honeywell, Inc., on a B-737 research aircraft to record a data base for evaluating the performance of a differential DGPS/inertial navigation system (INS) which used GPS Course/Acquisition code receivers. Estimates from the DGPS/INS and a Microwave Landing System (MLS)/INS, and various aircraft parameter data were recorded in real time aboard the aircraft while flying along the final approach path to landing. This paper presents the mean and standard deviation of the DGPS/INS and MLS/INS navigation position errors computed relative to the laser tracker system and of the difference between the DGPS/INS and MLS/INS velocity estimates. RMS errors are presented for DGPS/INS and MLS/INS guidance errors (localizer and glideslope). The mean navigation position errors and standard deviation of the x position coordinate of the DGPS/INS and MLS/INS systems were found to be of similar magnitude while the standard deviation of the y and z position coordinate errors were significantly larger for DGPS/INS compared to MLS/INS.

An emerging network storage management standard: Media error monitoring and reporting information (MEMRI) - to determine optical tape data integrity

NASA Technical Reports Server (NTRS)

Podio, Fernando; Vollrath, William; Williams, Joel; Kobler, Ben; Crouse, Don

1998-01-01

Sophisticated network storage management applications are rapidly evolving to satisfy a market demand for highly reliable data storage systems with large data storage capacities and performance requirements. To preserve a high degree of data integrity, these applications must rely on intelligent data storage devices that can provide reliable indicators of data degradation. Error correction activity generally occurs within storage devices without notification to the host. Early indicators of degradation and media error monitoring 333 and reporting (MEMR) techniques implemented in data storage devices allow network storage management applications to notify system administrators of these events and to take appropriate corrective actions before catastrophic errors occur. Although MEMR techniques have been implemented in data storage devices for many years, until 1996 no MEMR standards existed. In 1996 the American National Standards Institute (ANSI) approved the only known (world-wide) industry standard specifying MEMR techniques to verify stored data on optical disks. This industry standard was developed under the auspices of the Association for Information and Image Management (AIIM). A recently formed AIIM Optical Tape Subcommittee initiated the development of another data integrity standard specifying a set of media error monitoring tools and media error monitoring information (MEMRI) to verify stored data on optical tape media. This paper discusses the need for intelligent storage devices that can provide data integrity metadata, the content of the existing data integrity standard for optical disks, and the content of the MEMRI standard being developed by the AIIM Optical Tape Subcommittee.

Comparing interval estimates for small sample ordinal CFA models

PubMed Central

Natesan, Prathiba

2015-01-01

Robust maximum likelihood (RML) and asymptotically generalized least squares (AGLS) methods have been recommended for fitting ordinal structural equation models. Studies show that some of these methods underestimate standard errors. However, these studies have not investigated the coverage and bias of interval estimates. An estimate with a reasonable standard error could still be severely biased. This can only be known by systematically investigating the interval estimates. The present study compares Bayesian, RML, and AGLS interval estimates of factor correlations in ordinal confirmatory factor analysis models (CFA) for small sample data. Six sample sizes, 3 factor correlations, and 2 factor score distributions (multivariate normal and multivariate mildly skewed) were studied. Two Bayesian prior specifications, informative and relatively less informative were studied. Undercoverage of confidence intervals and underestimation of standard errors was common in non-Bayesian methods. Underestimated standard errors may lead to inflated Type-I error rates. Non-Bayesian intervals were more positive biased than negatively biased, that is, most intervals that did not contain the true value were greater than the true value. Some non-Bayesian methods had non-converging and inadmissible solutions for small samples and non-normal data. Bayesian empirical standard error estimates for informative and relatively less informative priors were closer to the average standard errors of the estimates. The coverage of Bayesian credibility intervals was closer to what was expected with overcoverage in a few cases. Although some Bayesian credibility intervals were wider, they reflected the nature of statistical uncertainty that comes with the data (e.g., small sample). Bayesian point estimates were also more accurate than non-Bayesian estimates. The results illustrate the importance of analyzing coverage and bias of interval estimates, and how ignoring interval estimates can be misleading. Therefore, editors and policymakers should continue to emphasize the inclusion of interval estimates in research. PMID:26579002

Comparing interval estimates for small sample ordinal CFA models.

PubMed

Natesan, Prathiba

2015-01-01

Robust maximum likelihood (RML) and asymptotically generalized least squares (AGLS) methods have been recommended for fitting ordinal structural equation models. Studies show that some of these methods underestimate standard errors. However, these studies have not investigated the coverage and bias of interval estimates. An estimate with a reasonable standard error could still be severely biased. This can only be known by systematically investigating the interval estimates. The present study compares Bayesian, RML, and AGLS interval estimates of factor correlations in ordinal confirmatory factor analysis models (CFA) for small sample data. Six sample sizes, 3 factor correlations, and 2 factor score distributions (multivariate normal and multivariate mildly skewed) were studied. Two Bayesian prior specifications, informative and relatively less informative were studied. Undercoverage of confidence intervals and underestimation of standard errors was common in non-Bayesian methods. Underestimated standard errors may lead to inflated Type-I error rates. Non-Bayesian intervals were more positive biased than negatively biased, that is, most intervals that did not contain the true value were greater than the true value. Some non-Bayesian methods had non-converging and inadmissible solutions for small samples and non-normal data. Bayesian empirical standard error estimates for informative and relatively less informative priors were closer to the average standard errors of the estimates. The coverage of Bayesian credibility intervals was closer to what was expected with overcoverage in a few cases. Although some Bayesian credibility intervals were wider, they reflected the nature of statistical uncertainty that comes with the data (e.g., small sample). Bayesian point estimates were also more accurate than non-Bayesian estimates. The results illustrate the importance of analyzing coverage and bias of interval estimates, and how ignoring interval estimates can be misleading. Therefore, editors and policymakers should continue to emphasize the inclusion of interval estimates in research.

Understanding Problem-Solving Errors by Students with Learning Disabilities in Standards-Based and Traditional Curricula

ERIC Educational Resources Information Center

Bouck, Emily C.; Bouck, Mary K.; Joshi, Gauri S.; Johnson, Linley

2016-01-01

Students with learning disabilities struggle with word problems in mathematics classes. Understanding the type of errors students make when working through such mathematical problems can further describe student performance and highlight student difficulties. Through the use of error codes, researchers analyzed the type of errors made by 14 sixth…

Effects of shape, size, and chromaticity of stimuli on estimated size in normally sighted, severely myopic, and visually impaired students.

PubMed

Huang, Kuo-Chen; Wang, Hsiu-Feng; Chen, Chun-Ching

2010-06-01

Effects of shape, size, and chromaticity of stimuli on participants' errors when estimating the size of simultaneously presented standard and comparison stimuli were examined. 48 Taiwanese college students ages 20 to 24 years old (M = 22.3, SD = 1.3) participated. Analysis showed that the error for estimated size was significantly greater for those in the low-vision group than for those in the normal-vision and severe-myopia groups. The errors were significantly greater with green and blue stimuli than with red stimuli. Circular stimuli produced smaller mean errors than did square stimuli. The actual size of the standard stimulus significantly affected the error for estimated size. Errors for estimations using smaller sizes were significantly higher than when the sizes were larger. Implications of the results for graphics-based interface design, particularly when taking account of visually impaired users, are discussed.

Intimate Partner Violence, 1993-2010

MedlinePlus

... appendix table 2 for standard errors. *Due to methodological changes, use caution when comparing 2006 NCVS criminal ... appendix table 2 for standard errors. *Due to methodological changes, use caution when comparing 2006 NCVS criminal ...

Computer Programs for the Semantic Differential: Further Modifications.

ERIC Educational Resources Information Center

Lawson, Edwin D.; And Others

The original nine programs for semantic differential analysis have been condensed into three programs which have been further refined and augmented. They yield: (1) means, standard deviations, and standard errors for each subscale on each concept; (2) Evaluation, Potency, and Activity (EPA) means, standard deviations, and standard errors; (3)…

Exploring Senior Residents' Intraoperative Error Management Strategies: A Potential Measure of Performance Improvement.

PubMed

Law, Katherine E; Ray, Rebecca D; D'Angelo, Anne-Lise D; Cohen, Elaine R; DiMarco, Shannon M; Linsmeier, Elyse; Wiegmann, Douglas A; Pugh, Carla M

The study aim was to determine whether residents' error management strategies changed across 2 simulated laparoscopic ventral hernia (LVH) repair procedures after receiving feedback on their initial performance. We hypothesize that error detection and recovery strategies would improve during the second procedure without hands-on practice. Retrospective review of participant procedural performances of simulated laparoscopic ventral herniorrhaphy. A total of 3 investigators reviewed procedure videos to identify surgical errors. Errors were deconstructed. Error management events were noted, including error identification and recovery. Residents performed the simulated LVH procedures during a course on advanced laparoscopy. Participants had 30 minutes to complete a LVH procedure. After verbal and simulator feedback, residents returned 24 hours later to perform a different, more difficult simulated LVH repair. Senior (N = 7; postgraduate year 4-5) residents in attendance at the course participated in this study. In the first LVH procedure, residents committed 121 errors (M = 17.14, standard deviation = 4.38). Although the number of errors increased to 146 (M = 20.86, standard deviation = 6.15) during the second procedure, residents progressed further in the second procedure. There was no significant difference in the number of errors committed for both procedures, but errors shifted to the late stage of the second procedure. Residents changed the error types that they attempted to recover (χ 2 5 =24.96, p<0.001). For the second procedure, recovery attempts increased for action and procedure errors, but decreased for strategy errors. Residents also recovered the most errors in the late stage of the second procedure (p < 0.001). Residents' error management strategies changed between procedures following verbal feedback on their initial performance and feedback from the simulator. Errors and recovery attempts shifted to later steps during the second procedure. This may reflect residents' error management success in the earlier stages, which allowed further progression in the second simulation. Incorporating error recognition and management opportunities into surgical training could help track residents' learning curve and provide detailed, structured feedback on technical and decision-making skills. Copyright © 2016 Association of Program Directors in Surgery. Published by Elsevier Inc. All rights reserved.

Methods for estimating flood frequency in Montana based on data through water year 1998

USGS Publications Warehouse

Parrett, Charles; Johnson, Dave R.

2004-01-01

Annual peak discharges having recurrence intervals of 2, 5, 10, 25, 50, 100, 200, and 500 years (T-year floods) were determined for 660 gaged sites in Montana and in adjacent areas of Idaho, Wyoming, and Canada, based on data through water year 1998. The updated flood-frequency information was subsequently used in regression analyses, either ordinary or generalized least squares, to develop equations relating T-year floods to various basin and climatic characteristics, equations relating T-year floods to active-channel width, and equations relating T-year floods to bankfull width. The equations can be used to estimate flood frequency at ungaged sites. Montana was divided into eight regions, within which flood characteristics were considered to be reasonably homogeneous, and the three sets of regression equations were developed for each region. A measure of the overall reliability of the regression equations is the average standard error of prediction. The average standard errors of prediction for the equations based on basin and climatic characteristics ranged from 37.4 percent to 134.1 percent. Average standard errors of prediction for the equations based on active-channel width ranged from 57.2 percent to 141.3 percent. Average standard errors of prediction for the equations based on bankfull width ranged from 63.1 percent to 155.5 percent. In most regions, the equations based on basin and climatic characteristics generally had smaller average standard errors of prediction than equations based on active-channel or bankfull width. An exception was the Southeast Plains Region, where all equations based on active-channel width had smaller average standard errors of prediction than equations based on basin and climatic characteristics or bankfull width. Methods for weighting estimates derived from the basin- and climatic-characteristic equations and the channel-width equations also were developed. The weights were based on the cross correlation of residuals from the different methods and the average standard errors of prediction. When all three methods were combined, the average standard errors of prediction ranged from 37.4 percent to 120.2 percent. Weighting of estimates reduced the standard errors of prediction for all T-year flood estimates in four regions, reduced the standard errors of prediction for some T-year flood estimates in two regions, and provided no reduction in average standard error of prediction in two regions. A computer program for solving the regression equations, weighting estimates, and determining reliability of individual estimates was developed and placed on the USGS Montana District World Wide Web page. A new regression method, termed Region of Influence regression, also was tested. Test results indicated that the Region of Influence method was not as reliable as the regional equations based on generalized least squares regression. Two additional methods for estimating flood frequency at ungaged sites located on the same streams as gaged sites also are described. The first method, based on a drainage-area-ratio adjustment, is intended for use on streams where the ungaged site of interest is located near a gaged site. The second method, based on interpolation between gaged sites, is intended for use on streams that have two or more streamflow-gaging stations.

WE-H-BRC-09: Simulated Errors in Mock Radiotherapy Plans to Quantify the Effectiveness of the Physics Plan Review

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gopan, O; Kalet, A; Smith, W

2016-06-15

Purpose: A standard tool for ensuring the quality of radiation therapy treatments is the initial physics plan review. However, little is known about its performance in practice. The goal of this study is to measure the effectiveness of physics plan review by introducing simulated errors into “mock” treatment plans and measuring the performance of plan review by physicists. Methods: We generated six mock treatment plans containing multiple errors. These errors were based on incident learning system data both within the department and internationally (SAFRON). These errors were scored for severity and frequency. Those with the highest scores were included inmore » the simulations (13 errors total). Observer bias was minimized using a multiple co-correlated distractor approach. Eight physicists reviewed these plans for errors, with each physicist reviewing, on average, 3/6 plans. The confidence interval for the proportion of errors detected was computed using the Wilson score interval. Results: Simulated errors were detected in 65% of reviews [51–75%] (95% confidence interval [CI] in brackets). The following error scenarios had the highest detection rates: incorrect isocenter in DRRs/CBCT (91% [73–98%]) and a planned dose different from the prescribed dose (100% [61–100%]). Errors with low detection rates involved incorrect field parameters in record and verify system (38%, [18–61%]) and incorrect isocenter localization in planning system (29% [8–64%]). Though pre-treatment QA failure was reliably identified (100%), less than 20% of participants reported the error that caused the failure. Conclusion: This is one of the first quantitative studies of error detection. Although physics plan review is a key safety measure and can identify some errors with high fidelity, others errors are more challenging to detect. This data will guide future work on standardization and automation. Creating new checks or improving existing ones (i.e., via automation) will help in detecting those errors with low detection rates.« less

Cost effectiveness of the US Geological Survey stream-gaging program in Alabama

USGS Publications Warehouse

Jeffcoat, H.H.

1987-01-01

A study of the cost effectiveness of the stream gaging program in Alabama identified data uses and funding sources for 72 surface water stations (including dam stations, slope stations, and continuous-velocity stations) operated by the U.S. Geological Survey in Alabama with a budget of $393,600. Of these , 58 gaging stations were used in all phases of the analysis at a funding level of $328,380. For the current policy of operation of the 58-station program, the average standard error of estimation of instantaneous discharge is 29.3%. This overall level of accuracy can be maintained with a budget of $319,800 by optimizing routes and implementing some policy changes. The maximum budget considered in the analysis was $361,200, which gave an average standard error of estimation of 20.6%. The minimum budget considered was $299,360, with an average standard error of estimation of 36.5%. The study indicates that a major source of error in the stream gaging records is lost or missing data that are the result of streamside equipment failure. If perfect equipment were available, the standard error in estimating instantaneous discharge under the current program and budget could be reduced to 18.6%. This can also be interpreted to mean that the streamflow data records have a standard error of this magnitude during times when the equipment is operating properly. (Author 's abstract)

78 FR 17155 - Standards for the Growing, Harvesting, Packing, and Holding of Produce for Human Consumption...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-03-20

...The Food and Drug Administration (FDA or we) is correcting the preamble to a proposed rule that published in the Federal Register of January 16, 2013. That proposed rule would establish science-based minimum standards for the safe growing, harvesting, packing, and holding of produce, meaning fruits and vegetables grown for human consumption. FDA proposed these standards as part of our implementation of the FDA Food Safety Modernization Act. The document published with several technical errors, including some errors in cross references, as well as several errors in reference numbers cited throughout the document. This document corrects those errors. We are also placing a corrected copy of the proposed rule in the docket.

Hedonic price models with omitted variables and measurement errors: a constrained autoregression-structural equation modeling approach with application to urban Indonesia

NASA Astrophysics Data System (ADS)

Suparman, Yusep; Folmer, Henk; Oud, Johan H. L.

2014-01-01

Omitted variables and measurement errors in explanatory variables frequently occur in hedonic price models. Ignoring these problems leads to biased estimators. In this paper, we develop a constrained autoregression-structural equation model (ASEM) to handle both types of problems. Standard panel data models to handle omitted variables bias are based on the assumption that the omitted variables are time-invariant. ASEM allows handling of both time-varying and time-invariant omitted variables by constrained autoregression. In the case of measurement error, standard approaches require additional external information which is usually difficult to obtain. ASEM exploits the fact that panel data are repeatedly measured which allows decomposing the variance of a variable into the true variance and the variance due to measurement error. We apply ASEM to estimate a hedonic housing model for urban Indonesia. To get insight into the consequences of measurement error and omitted variables, we compare the ASEM estimates with the outcomes of (1) a standard SEM, which does not account for omitted variables, (2) a constrained autoregression model, which does not account for measurement error, and (3) a fixed effects hedonic model, which ignores measurement error and time-varying omitted variables. The differences between the ASEM estimates and the outcomes of the three alternative approaches are substantial.

Towards reporting standards for neuropsychological study results: A proposal to minimize communication errors with standardized qualitative descriptors for normalized test scores.

PubMed

Schoenberg, Mike R; Rum, Ruba S

2017-11-01

Rapid, clear and efficient communication of neuropsychological results is essential to benefit patient care. Errors in communication are a lead cause of medical errors; nevertheless, there remains a lack of consistency in how neuropsychological scores are communicated. A major limitation in the communication of neuropsychological results is the inconsistent use of qualitative descriptors for standardized test scores and the use of vague terminology. PubMed search from 1 Jan 2007 to 1 Aug 2016 to identify guidelines or consensus statements for the description and reporting of qualitative terms to communicate neuropsychological test scores was conducted. The review found the use of confusing and overlapping terms to describe various ranges of percentile standardized test scores. In response, we propose a simplified set of qualitative descriptors for normalized test scores (Q-Simple) as a means to reduce errors in communicating test results. The Q-Simple qualitative terms are: 'very superior', 'superior', 'high average', 'average', 'low average', 'borderline' and 'abnormal/impaired'. A case example illustrates the proposed Q-Simple qualitative classification system to communicate neuropsychological results for neurosurgical planning. The Q-Simple qualitative descriptor system is aimed as a means to improve and standardize communication of standardized neuropsychological test scores. Research are needed to further evaluate neuropsychological communication errors. Conveying the clinical implications of neuropsychological results in a manner that minimizes risk for communication errors is a quintessential component of evidence-based practice. Copyright © 2017 Elsevier B.V. All rights reserved.

Discrepancy-based error estimates for Quasi-Monte Carlo III. Error distributions and central limits

NASA Astrophysics Data System (ADS)

Hoogland, Jiri; Kleiss, Ronald

1997-04-01

In Quasi-Monte Carlo integration, the integration error is believed to be generally smaller than in classical Monte Carlo with the same number of integration points. Using an appropriate definition of an ensemble of quasi-random point sets, we derive various results on the probability distribution of the integration error, which can be compared to the standard Central Limit Theorem for normal stochastic sampling. In many cases, a Gaussian error distribution is obtained.

Accuracy of acoustic velocity metering systems for measurement of low velocity in open channels

USGS Publications Warehouse

Laenen, Antonius; Curtis, R. E.

1989-01-01

Acoustic velocity meter (AVM) accuracy depends on equipment limitations, the accuracy of acoustic-path length and angle determination, and the stability of the mean velocity to acoustic-path velocity relation. Equipment limitations depend on path length and angle, transducer frequency, timing oscillator frequency, and signal-detection scheme. Typically, the velocity error from this source is about +or-1 to +or-10 mms/sec. Error in acoustic-path angle or length will result in a proportional measurement bias. Typically, an angle error of one degree will result in a velocity error of 2%, and a path-length error of one meter in 100 meter will result in an error of 1%. Ray bending (signal refraction) depends on path length and density gradients present in the stream. Any deviation from a straight acoustic path between transducer will change the unique relation between path velocity and mean velocity. These deviations will then introduce error in the mean velocity computation. Typically, for a 200-meter path length, the resultant error is less than one percent, but for a 1,000 meter path length, the error can be greater than 10%. Recent laboratory and field tests have substantiated assumptions of equipment limitations. Tow-tank tests of an AVM system with a 4.69-meter path length yielded an average standard deviation error of 9.3 mms/sec, and the field tests of an AVM system with a 20.5-meter path length yielded an average standard deviation error of a 4 mms/sec. (USGS)

Significant and Sustained Reduction in Chemotherapy Errors Through Improvement Science.

PubMed

Weiss, Brian D; Scott, Melissa; Demmel, Kathleen; Kotagal, Uma R; Perentesis, John P; Walsh, Kathleen E

2017-04-01

A majority of children with cancer are now cured with highly complex chemotherapy regimens incorporating multiple drugs and demanding monitoring schedules. The risk for error is high, and errors can occur at any stage in the process, from order generation to pharmacy formulation to bedside drug administration. Our objective was to describe a program to eliminate errors in chemotherapy use among children. To increase reporting of chemotherapy errors, we supplemented the hospital reporting system with a new chemotherapy near-miss reporting system. After the model for improvement, we then implemented several interventions, including a daily chemotherapy huddle, improvements to the preparation and delivery of intravenous therapy, headphones for clinicians ordering chemotherapy, and standards for chemotherapy administration throughout the hospital. Twenty-two months into the project, we saw a centerline shift in our U chart of chemotherapy errors that reached the patient from a baseline rate of 3.8 to 1.9 per 1,000 doses. This shift has been sustained for > 4 years. In Poisson regression analyses, we found an initial increase in error rates, followed by a significant decline in errors after 16 months of improvement work ( P < .001). After the model for improvement, our improvement efforts were associated with significant reductions in chemotherapy errors that reached the patient. Key drivers for our success included error vigilance through a huddle, standardization, and minimization of interruptions during ordering.

Safe and effective error rate monitors for SS7 signaling links

NASA Astrophysics Data System (ADS)

Schmidt, Douglas C.

1994-04-01

This paper describes SS7 error monitor characteristics, discusses the existing SUERM (Signal Unit Error Rate Monitor), and develops the recently proposed EIM (Error Interval Monitor) for higher speed SS7 links. A SS7 error monitor is considered safe if it ensures acceptable link quality and is considered effective if it is tolerant to short-term phenomena. Formal criteria for safe and effective error monitors are formulated in this paper. This paper develops models of changeover transients, the unstable component of queue length resulting from errors. These models are in the form of recursive digital filters. Time is divided into sequential intervals. The filter's input is the number of errors which have occurred in each interval. The output is the corresponding change in transmit queue length. Engineered EIM's are constructed by comparing an estimated changeover transient with a threshold T using a transient model modified to enforce SS7 standards. When this estimate exceeds T, a changeover will be initiated and the link will be removed from service. EIM's can be differentiated from SUERM by the fact that EIM's monitor errors over an interval while SUERM's count errored messages. EIM's offer several advantages over SUERM's, including the fact that they are safe and effective, impose uniform standards in link quality, are easily implemented, and make minimal use of real-time resources.

Lexico-Semantic Errors of the Learners of English: A Survey of Standard Seven Keiyo-Speaking Primary School Pupils in Keiyo District, Kenya

ERIC Educational Resources Information Center

Jeptarus, Kipsamo E.; Ngene, Patrick K.

2016-01-01

The purpose of this research was to study the Lexico-semantic errors of the Keiyo-speaking standard seven primary school learners of English as a Second Language (ESL) in Keiyo District, Kenya. This study was guided by two related theories: Error Analysis Theory/Approach by Corder (1971) which approaches L2 learning through a detailed analysis of…

Evaluation of seasonal and spatial variations of lumped water balance model sensitivity to precipitation data errors

NASA Astrophysics Data System (ADS)

Xu, Chong-yu; Tunemar, Liselotte; Chen, Yongqin David; Singh, V. P.

2006-06-01

Sensitivity of hydrological models to input data errors have been reported in the literature for particular models on a single or a few catchments. A more important issue, i.e. how model's response to input data error changes as the catchment conditions change has not been addressed previously. This study investigates the seasonal and spatial effects of precipitation data errors on the performance of conceptual hydrological models. For this study, a monthly conceptual water balance model, NOPEX-6, was applied to 26 catchments in the Mälaren basin in Central Sweden. Both systematic and random errors were considered. For the systematic errors, 5-15% of mean monthly precipitation values were added to the original precipitation to form the corrupted input scenarios. Random values were generated by Monte Carlo simulation and were assumed to be (1) independent between months, and (2) distributed according to a Gaussian law of zero mean and constant standard deviation that were taken as 5, 10, 15, 20, and 25% of the mean monthly standard deviation of precipitation. The results show that the response of the model parameters and model performance depends, among others, on the type of the error, the magnitude of the error, physical characteristics of the catchment, and the season of the year. In particular, the model appears less sensitive to the random error than to the systematic error. The catchments with smaller values of runoff coefficients were more influenced by input data errors than were the catchments with higher values. Dry months were more sensitive to precipitation errors than were wet months. Recalibration of the model with erroneous data compensated in part for the data errors by altering the model parameters.

The Measurement and Correction of the Periodic Error of the LX200-16 Telescope Driving System

NASA Astrophysics Data System (ADS)

Jeong, Jang Hae; Lee, Young Sam; Lee, Chung Uk

2000-06-01

We examined and corrected the periodic error of the LX200-16 Telescope driving system of Chungbuk National University Campus Observatory. Before correcting, the standard deviation of the periodic error in the direction of East-West was = 7.''2. After correcting,we found that the periodic error was reduced to = 1.''2.

Mimicking Aphasic Semantic Errors in Normal Speech Production: Evidence from a Novel Experimental Paradigm

ERIC Educational Resources Information Center

Hodgson, Catherine; Lambon Ralph, Matthew A.

2008-01-01

Semantic errors are commonly found in semantic dementia (SD) and some forms of stroke aphasia and provide insights into semantic processing and speech production. Low error rates are found in standard picture naming tasks in normal controls. In order to increase error rates and thus provide an experimental model of aphasic performance, this study…

Cost-effectiveness of the stream-gaging program in Nebraska

USGS Publications Warehouse

Engel, G.B.; Wahl, K.L.; Boohar, J.A.

1984-01-01

This report documents the results of a study of the cost-effectiveness of the streamflow information program in Nebraska. Presently, 145 continuous surface-water stations are operated in Nebraska on a budget of $908,500. Data uses and funding sources are identified for each of the 145 stations. Data from most stations have multiple uses. All stations have sufficient justification for continuation, but two stations primarily are used in short-term research studies; their continued operation needs to be evaluated when the research studies end. The present measurement frequency produces an average standard error for instantaneous discharges of about 12 percent, including periods when stage data are missing. Altering the travel routes and the measurement frequency will allow a reduction in standard error of about 1 percent with the present budget. Standard error could be reduced to about 8 percent if lost record could be eliminated. A minimum budget of $822,000 is required to operate the present network, but operations at that funding level would result in an increase in standard error to about 16 percent. The maximum budget analyzed was $1,363,000, which would result in an average standard error of 6 percent. (USGS)

Incorporating Measurement Error from Modeled Air Pollution Exposures into Epidemiological Analyses.

PubMed

Samoli, Evangelia; Butland, Barbara K

2017-12-01

Outdoor air pollution exposures used in epidemiological studies are commonly predicted from spatiotemporal models incorporating limited measurements, temporal factors, geographic information system variables, and/or satellite data. Measurement error in these exposure estimates leads to imprecise estimation of health effects and their standard errors. We reviewed methods for measurement error correction that have been applied in epidemiological studies that use model-derived air pollution data. We identified seven cohort studies and one panel study that have employed measurement error correction methods. These methods included regression calibration, risk set regression calibration, regression calibration with instrumental variables, the simulation extrapolation approach (SIMEX), and methods under the non-parametric or parameter bootstrap. Corrections resulted in small increases in the absolute magnitude of the health effect estimate and its standard error under most scenarios. Limited application of measurement error correction methods in air pollution studies may be attributed to the absence of exposure validation data and the methodological complexity of the proposed methods. Future epidemiological studies should consider in their design phase the requirements for the measurement error correction method to be later applied, while methodological advances are needed under the multi-pollutants setting.

How Do Simulated Error Experiences Impact Attitudes Related to Error Prevention?

PubMed

Breitkreuz, Karen R; Dougal, Renae L; Wright, Melanie C

2016-10-01

The objective of this project was to determine whether simulated exposure to error situations changes attitudes in a way that may have a positive impact on error prevention behaviors. Using a stratified quasi-randomized experiment design, we compared risk perception attitudes of a control group of nursing students who received standard error education (reviewed medication error content and watched movies about error experiences) to an experimental group of students who reviewed medication error content and participated in simulated error experiences. Dependent measures included perceived memorability of the educational experience, perceived frequency of errors, and perceived caution with respect to preventing errors. Experienced nursing students perceived the simulated error experiences to be more memorable than movies. Less experienced students perceived both simulated error experiences and movies to be highly memorable. After the intervention, compared with movie participants, simulation participants believed errors occurred more frequently. Both types of education increased the participants' intentions to be more cautious and reported caution remained higher than baseline for medication errors 6 months after the intervention. This study provides limited evidence of an advantage of simulation over watching movies describing actual errors with respect to manipulating attitudes related to error prevention. Both interventions resulted in long-term impacts on perceived caution in medication administration. Simulated error experiences made participants more aware of how easily errors can occur, and the movie education made participants more aware of the devastating consequences of errors.

Biases and Standard Errors of Standardized Regression Coefficients

ERIC Educational Resources Information Center

Yuan, Ke-Hai; Chan, Wai

2011-01-01

The paper obtains consistent standard errors (SE) and biases of order O(1/n) for the sample standardized regression coefficients with both random and given predictors. Analytical results indicate that the formulas for SEs given in popular text books are consistent only when the population value of the regression coefficient is zero. The sample…

Effect of photogrammetric reading error on slope-frequency distributions. [obtained from Apollo 17 mission

NASA Technical Reports Server (NTRS)

Moore, H. J.; Wu, S. C.

1973-01-01

The effect of reading error on two hypothetical slope frequency distributions and two slope frequency distributions from actual lunar data in order to ensure that these errors do not cause excessive overestimates of algebraic standard deviations for the slope frequency distributions. The errors introduced are insignificant when the reading error is small and the slope length is large. A method for correcting the errors in slope frequency distributions is presented and applied to 11 distributions obtained from Apollo 15, 16, and 17 panoramic camera photographs and Apollo 16 metric camera photographs.

Error-Based Design Space Windowing

NASA Technical Reports Server (NTRS)

Papila, Melih; Papila, Nilay U.; Shyy, Wei; Haftka, Raphael T.; Fitz-Coy, Norman

2002-01-01

Windowing of design space is considered in order to reduce the bias errors due to low-order polynomial response surfaces (RS). Standard design space windowing (DSW) uses a region of interest by setting a requirement on response level and checks it by a global RS predictions over the design space. This approach, however, is vulnerable since RS modeling errors may lead to the wrong region to zoom on. The approach is modified by introducing an eigenvalue error measure based on point-to-point mean squared error criterion. Two examples are presented to demonstrate the benefit of the error-based DSW.

Carbapenem Susceptibility Testing Errors Using Three Automated Systems, Disk Diffusion, Etest, and Broth Microdilution and Carbapenem Resistance Genes in Isolates of Acinetobacter baumannii-calcoaceticus Complex

DTIC Science & Technology

2011-10-01

Phoenix, and Vitek 2 systems). Discordant results were categorized as very major errors (VME), major errors (ME), and minor errors (mE). DNA sequences...01 OCT 2011 2 . REPORT TYPE N/A 3. DATES COVERED - 4. TITLE AND SUBTITLE Carbapenem Susceptibility Testing Errors Using Three Automated...FDA standards required for device approval (11). The Vitek 2 method was the only automated susceptibility method in our study that satisfied FDA

WE-H-BRC-05: Catastrophic Error Metrics for Radiation Therapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Murphy, S; Molloy, J

Purpose: Intuitive evaluation of complex radiotherapy treatments is impractical, while data transfer anomalies create the potential for catastrophic treatment delivery errors. Contrary to prevailing wisdom, logical scrutiny can be applied to patient-specific machine settings. Such tests can be automated, applied at the point of treatment delivery and can be dissociated from prior states of the treatment plan, potentially revealing errors introduced early in the process. Methods: Analytical metrics were formulated for conventional and intensity modulated RT (IMRT) treatments. These were designed to assess consistency between monitor unit settings, wedge values, prescription dose and leaf positioning (IMRT). Institutional metric averages formore » 218 clinical plans were stratified over multiple anatomical sites. Treatment delivery errors were simulated using a commercial treatment planning system and metric behavior assessed via receiver-operator-characteristic (ROC) analysis. A positive result was returned if the erred plan metric value exceeded a given number of standard deviations, e.g. 2. The finding was declared true positive if the dosimetric impact exceeded 25%. ROC curves were generated over a range of metric standard deviations. Results: Data for the conventional treatment metric indicated standard deviations of 3%, 12%, 11%, 8%, and 5 % for brain, pelvis, abdomen, lung and breast sites, respectively. Optimum error declaration thresholds yielded true positive rates (TPR) between 0.7 and 1, and false positive rates (FPR) between 0 and 0.2. Two proposed IMRT metrics possessed standard deviations of 23% and 37%. The superior metric returned TPR and FPR of 0.7 and 0.2, respectively, when both leaf position and MUs were modelled. Isolation to only leaf position errors yielded TPR and FPR values of 0.9 and 0.1. Conclusion: Logical tests can reveal treatment delivery errors and prevent large, catastrophic errors. Analytical metrics are able to identify errors in monitor units, wedging and leaf positions with favorable sensitivity and specificity. In part by Varian.« less

Error image aware content restoration

NASA Astrophysics Data System (ADS)

Choi, Sungwoo; Lee, Moonsik; Jung, Byunghee

2015-12-01

As the resolution of TV significantly increased, content consumers have become increasingly sensitive to the subtlest defect in TV contents. This rising standard in quality demanded by consumers has posed a new challenge in today's context where the tape-based process has transitioned to the file-based process: the transition necessitated digitalizing old archives, a process which inevitably produces errors such as disordered pixel blocks, scattered white noise, or totally missing pixels. Unsurprisingly, detecting and fixing such errors require a substantial amount of time and human labor to meet the standard demanded by today's consumers. In this paper, we introduce a novel, automated error restoration algorithm which can be applied to different types of classic errors by utilizing adjacent images while preserving the undamaged parts of an error image as much as possible. We tested our method to error images detected from our quality check system in KBS(Korean Broadcasting System) video archive. We are also implementing the algorithm as a plugin of well-known NLE(Non-linear editing system), which is a familiar tool for quality control agent.

Toward a new culture in verified quantum operations

NASA Astrophysics Data System (ADS)

Flammia, Steve

Measuring error rates of quantum operations has become an indispensable component in any aspiring platform for quantum computation. As the quality of controlled quantum operations increases, the demands on the accuracy and precision with which we measure these error rates also grows. However, well-meaning scientists that report these error measures are faced with a sea of non-standardized methodologies and are often asked during publication for only coarse information about how their estimates were obtained. Moreover, there are serious incentives to use methodologies and measures that will continually produce numbers that improve with time to show progress. These problems will only get exacerbated as our typical error rates go from 1 in 100 to 1 in 1000 or less. This talk will survey existing challenges presented by the current paradigm and offer some suggestions for solutions than can help us move toward fair and standardized methods for error metrology in quantum computing experiments, and towards a culture that values full disclose of methodologies and higher standards for data analysis.

Second Chance: If at First You Do Not Succeed, Set up a Plan and Try, Try Again

ERIC Educational Resources Information Center

Poulsen, John

2012-01-01

Student teachers make errors in their practicum. Then, they learn and fix those errors. This is the standard arc within a successful practicum. Some students make errors that they do not fix and then make more errors that again remain unfixed. This downward spiral increases in pace until the classroom becomes chaos. These students at the…

Application of advanced shearing techniques to the calibration of autocollimators with small angle generators and investigation of error sources.

PubMed

Yandayan, T; Geckeler, R D; Aksulu, M; Akgoz, S A; Ozgur, B

2016-05-01

The application of advanced error-separating shearing techniques to the precise calibration of autocollimators with Small Angle Generators (SAGs) was carried out for the first time. The experimental realization was achieved using the High Precision Small Angle Generator (HPSAG) of TUBITAK UME under classical dimensional metrology laboratory environmental conditions. The standard uncertainty value of 5 mas (24.2 nrad) reached by classical calibration method was improved to the level of 1.38 mas (6.7 nrad). Shearing techniques, which offer a unique opportunity to separate the errors of devices without recourse to any external standard, were first adapted by Physikalisch-Technische Bundesanstalt (PTB) to the calibration of autocollimators with angle encoders. It has been demonstrated experimentally in a clean room environment using the primary angle standard of PTB (WMT 220). The application of the technique to a different type of angle measurement system extends the range of the shearing technique further and reveals other advantages. For example, the angular scales of the SAGs are based on linear measurement systems (e.g., capacitive nanosensors for the HPSAG). Therefore, SAGs show different systematic errors when compared to angle encoders. In addition to the error-separation of HPSAG and the autocollimator, detailed investigations on error sources were carried out. Apart from determination of the systematic errors of the capacitive sensor used in the HPSAG, it was also demonstrated that the shearing method enables the unique opportunity to characterize other error sources such as errors due to temperature drift in long term measurements. This proves that the shearing technique is a very powerful method for investigating angle measuring systems, for their improvement, and for specifying precautions to be taken during the measurements.

Error-compensation model for simultaneous measurement of five degrees of freedom motion errors of a rotary axis

NASA Astrophysics Data System (ADS)

Bao, Chuanchen; Li, Jiakun; Feng, Qibo; Zhang, Bin

2018-07-01

This paper introduces an error-compensation model for our measurement method to measure five motion errors of a rotary axis based on fibre laser collimation. The error-compensation model is established in a matrix form using the homogeneous coordinate transformation theory. The influences of the installation errors, error crosstalk, and manufacturing errors are analysed. The model is verified by both ZEMAX simulation and measurement experiments. The repeatability values of the radial and axial motion errors are significantly suppressed by more than 50% after compensation. The repeatability experiments of five degrees of freedom motion errors and the comparison experiments of two degrees of freedom motion errors of an indexing table were performed by our measuring device and a standard instrument. The results show that the repeatability values of the angular positioning error ε z and tilt motion error around the Y axis ε y are 1.2″ and 4.4″, and the comparison deviations of the two motion errors are 4.0″ and 4.4″, respectively. The repeatability values of the radial and axial motion errors, δ y and δ z , are 1.3 and 0.6 µm, respectively. The repeatability value of the tilt motion error around the X axis ε x is 3.8″.

The Effect of Random Error on Diagnostic Accuracy Illustrated with the Anthropometric Diagnosis of Malnutrition

PubMed Central

2016-01-01

Background It is often thought that random measurement error has a minor effect upon the results of an epidemiological survey. Theoretically, errors of measurement should always increase the spread of a distribution. Defining an illness by having a measurement outside an established healthy range will lead to an inflated prevalence of that condition if there are measurement errors. Methods and results A Monte Carlo simulation was conducted of anthropometric assessment of children with malnutrition. Random errors of increasing magnitude were imposed upon the populations and showed that there was an increase in the standard deviation with each of the errors that became exponentially greater with the magnitude of the error. The potential magnitude of the resulting error of reported prevalence of malnutrition were compared with published international data and found to be of sufficient magnitude to make a number of surveys and the numerous reports and analyses that used these data unreliable. Conclusions The effect of random error in public health surveys and the data upon which diagnostic cut-off points are derived to define “health” has been underestimated. Even quite modest random errors can more than double the reported prevalence of conditions such as malnutrition. Increasing sample size does not address this problem, and may even result in less accurate estimates. More attention needs to be paid to the selection, calibration and maintenance of instruments, measurer selection, training & supervision, routine estimation of the likely magnitude of errors using standardization tests, use of statistical likelihood of error to exclude data from analysis and full reporting of these procedures in order to judge the reliability of survey reports. PMID:28030627

Molecular radiotherapy: the NUKFIT software for calculating the time-integrated activity coefficient.

PubMed

Kletting, P; Schimmel, S; Kestler, H A; Hänscheid, H; Luster, M; Fernández, M; Bröer, J H; Nosske, D; Lassmann, M; Glatting, G

2013-10-01

Calculation of the time-integrated activity coefficient (residence time) is a crucial step in dosimetry for molecular radiotherapy. However, available software is deficient in that it is either not tailored for the use in molecular radiotherapy and/or does not include all required estimation methods. The aim of this work was therefore the development and programming of an algorithm which allows for an objective and reproducible determination of the time-integrated activity coefficient and its standard error. The algorithm includes the selection of a set of fitting functions from predefined sums of exponentials and the choice of an error model for the used data. To estimate the values of the adjustable parameters an objective function, depending on the data, the parameters of the error model, the fitting function and (if required and available) Bayesian information, is minimized. To increase reproducibility and user-friendliness the starting values are automatically determined using a combination of curve stripping and random search. Visual inspection, the coefficient of determination, the standard error of the fitted parameters, and the correlation matrix are provided to evaluate the quality of the fit. The functions which are most supported by the data are determined using the corrected Akaike information criterion. The time-integrated activity coefficient is estimated by analytically integrating the fitted functions. Its standard error is determined assuming Gaussian error propagation. The software was implemented using MATLAB. To validate the proper implementation of the objective function and the fit functions, the results of NUKFIT and SAAM numerical, a commercially available software tool, were compared. The automatic search for starting values was successfully tested for reproducibility. The quality criteria applied in conjunction with the Akaike information criterion allowed the selection of suitable functions. Function fit parameters and their standard error estimated by using SAAM numerical and NUKFIT showed differences of <1%. The differences for the time-integrated activity coefficients were also <1% (standard error between 0.4% and 3%). In general, the application of the software is user-friendly and the results are mathematically correct and reproducible. An application of NUKFIT is presented for three different clinical examples. The software tool with its underlying methodology can be employed to objectively and reproducibly estimate the time integrated activity coefficient and its standard error for most time activity data in molecular radiotherapy.

Physician's error: medical or legal concept?

PubMed

Mujovic-Zornic, Hajrija M

2010-06-01

This article deals with the common term of different physician's errors that often happen in daily practice of health care. Author begins with the term of medical malpractice, defined broadly as practice of unjustified acts or failures to act upon the part of a physician or other health care professionals, which results in harm to the patient. It is a common term that includes many types of medical errors, especially physician's errors. The author also discusses the concept of physician's error in particular, which is understood no more in traditional way only as classic error in acting something manually wrong without necessary skills (medical concept), but as an error which violates patient's basic rights and which has its final legal consequence (legal concept). In every case the essential element of liability is to establish this error as a breach of the physician's duty. The first point to note is that the standard of procedure and the standard of due care against which the physician will be judged is not going to be that of the ordinary reasonable man who enjoys no medical expertise. The court's decision should give finale answer and legal qualification in each concrete case. The author's conclusion is that higher protection of human rights in the area of health equaly demands broader concept of physician's error with the accent to its legal subject matter.

Decoding of DBEC-TBED Reed-Solomon codes. [Double-Byte-Error-Correcting, Triple-Byte-Error-Detecting

NASA Technical Reports Server (NTRS)

Deng, Robert H.; Costello, Daniel J., Jr.

1987-01-01

A problem in designing semiconductor memories is to provide some measure of error control without requiring excessive coding overhead or decoding time. In LSI and VLSI technology, memories are often organized on a multiple bit (or byte) per chip basis. For example, some 256 K bit DRAM's are organized in 32 K x 8 bit-bytes. Byte-oriented codes such as Reed-Solomon (RS) codes can provide efficient low overhead error control for such memories. However, the standard iterative algorithm for decoding RS codes is too slow for these applications. The paper presents a special decoding technique for double-byte-error-correcting, triple-byte-error-detecting RS codes which is capable of high-speed operation. This technique is designed to find the error locations and the error values directly from the syndrome without having to use the iterative algorithm to find the error locator polynomial.

How personal standards perfectionism and evaluative concerns perfectionism affect the error positivity and post-error behavior with varying stimulus visibility.

PubMed

Drizinsky, Jessica; Zülch, Joachim; Gibbons, Henning; Stahl, Jutta

2016-10-01

Error detection is required in order to correct or avoid imperfect behavior. Although error detection is beneficial for some people, for others it might be disturbing. We investigated Gaudreau and Thompson's (Personality and Individual Differences, 48, 532-537, 2010) model, which combines personal standards perfectionism (PSP) and evaluative concerns perfectionism (ECP). In our electrophysiological study, 43 participants performed a combination of a modified Simon task, an error awareness paradigm, and a masking task with a variation of stimulus onset asynchrony (SOA; 33, 67, and 100 ms). Interestingly, relative to low-ECP participants, high-ECP participants showed a better post-error accuracy (despite a worse classification accuracy) in the high-visibility SOA 100 condition than in the two low-visibility conditions (SOA 33 and SOA 67). Regarding the electrophysiological results, first, we found a positive correlation between ECP and the amplitude of the error positivity (Pe) under conditions of low stimulus visibility. Second, under the condition of high stimulus visibility, we observed a higher Pe amplitude for high-ECP-low-PSP participants than for high-ECP-high-PSP participants. These findings are discussed within the framework of the error-processing avoidance hypothesis of perfectionism (Stahl, Acharki, Kresimon, Völler, & Gibbons, International Journal of Psychophysiology, 97, 153-162, 2015).

Fast decoding techniques for extended single-and-double-error-correcting Reed Solomon codes

NASA Technical Reports Server (NTRS)

Costello, D. J., Jr.; Deng, H.; Lin, S.

1984-01-01

A problem in designing semiconductor memories is to provide some measure of error control without requiring excessive coding overhead or decoding time. For example, some 256K-bit dynamic random access memories are organized as 32K x 8 bit-bytes. Byte-oriented codes such as Reed Solomon (RS) codes provide efficient low overhead error control for such memories. However, the standard iterative algorithm for decoding RS codes is too slow for these applications. Some special high speed decoding techniques for extended single and double error correcting RS codes. These techniques are designed to find the error locations and the error values directly from the syndrome without having to form the error locator polynomial and solve for its roots.

After the Medication Error: Recent Nursing Graduates' Reflections on Adequacy of Education.

PubMed

Treiber, Linda A; Jones, Jackie H

2018-05-01

The purpose of this study was to better understand individual- and system-level factors surrounding making a medication error from the perspective of recent Bachelor of Science in Nursing graduates. Online survey mixed-methods items included perceptions of adequacy of preparatory nursing education, contributory variables, emotional responses, and treatment by employer following the error. Of the 168 respondents, 55% had made a medication error. Errors resulted from inexperience, rushing, technology, staffing, and patient acuity. Twenty-four percent did not report their errors. Key themes for improving education included more practice in varied clinical areas, intensive pharmacological preparation, practical instruction in functioning within the health care environment, and coping after making medication errors. Errors generally caused emotional distress in the error maker. Overall, perceived treatment after the error reflected supportive environments, where nurses were generally treated with respect, fair treatment, and understanding. Opportunities for nursing education include second victim awareness and reinforcing professional practice standards. [J Nurs Educ. 2018;57(5):275-280.]. Copyright 2018, SLACK Incorporated.

Comparison of Optimal Design Methods in Inverse Problems

DTIC Science & Technology

2011-05-11

corresponding FIM can be estimated by F̂ (τ) = F̂ (τ, θ̂OLS) = (Σ̂ N (θ̂OLS)) −1. (13) The asymptotic standard errors are given by SEk (θ0) = √ (ΣN0 )kk, k...1, . . . , p. (14) These standard errors are estimated in practice (when θ0 and σ0 are not known) by SEk (θ̂OLS) = √ (Σ̂N (θ̂OLS))kk, k = 1... SEk (θ̂boot) = √ Cov(θ̂boot)kk. We will compare the optimal design methods using the standard errors resulting from the op- timal time points each

Hospital-based transfusion error tracking from 2005 to 2010: identifying the key errors threatening patient transfusion safety.

PubMed

Maskens, Carolyn; Downie, Helen; Wendt, Alison; Lima, Ana; Merkley, Lisa; Lin, Yulia; Callum, Jeannie

2014-01-01

This report provides a comprehensive analysis of transfusion errors occurring at a large teaching hospital and aims to determine key errors that are threatening transfusion safety, despite implementation of safety measures. Errors were prospectively identified from 2005 to 2010. Error data were coded on a secure online database called the Transfusion Error Surveillance System. Errors were defined as any deviation from established standard operating procedures. Errors were identified by clinical and laboratory staff. Denominator data for volume of activity were used to calculate rates. A total of 15,134 errors were reported with a median number of 215 errors per month (range, 85-334). Overall, 9083 (60%) errors occurred on the transfusion service and 6051 (40%) on the clinical services. In total, 23 errors resulted in patient harm: 21 of these errors occurred on the clinical services and two in the transfusion service. Of the 23 harm events, 21 involved inappropriate use of blood. Errors with no harm were 657 times more common than events that caused harm. The most common high-severity clinical errors were sample labeling (37.5%) and inappropriate ordering of blood (28.8%). The most common high-severity error in the transfusion service was sample accepted despite not meeting acceptance criteria (18.3%). The cost of product and component loss due to errors was $593,337. Errors occurred at every point in the transfusion process, with the greatest potential risk of patient harm resulting from inappropriate ordering of blood products and errors in sample labeling. © 2013 American Association of Blood Banks (CME).

Reducing number entry errors: solving a widespread, serious problem.

PubMed

Thimbleby, Harold; Cairns, Paul

2010-10-06

Number entry is ubiquitous: it is required in many fields including science, healthcare, education, government, mathematics and finance. People entering numbers are to be expected to make errors, but shockingly few systems make any effort to detect, block or otherwise manage errors. Worse, errors may be ignored but processed in arbitrary ways, with unintended results. A standard class of error (defined in the paper) is an 'out by 10 error', which is easily made by miskeying a decimal point or a zero. In safety-critical domains, such as drug delivery, out by 10 errors generally have adverse consequences. Here, we expose the extent of the problem of numeric errors in a very wide range of systems. An analysis of better error management is presented: under reasonable assumptions, we show that the probability of out by 10 errors can be halved by better user interface design. We provide a demonstration user interface to show that the approach is practical.To kill an error is as good a service as, and sometimes even better than, the establishing of a new truth or fact. (Charles Darwin 1879 [2008], p. 229).

Error control for reliable digital data transmission and storage systems

NASA Technical Reports Server (NTRS)

Costello, D. J., Jr.; Deng, R. H.

1985-01-01

A problem in designing semiconductor memories is to provide some measure of error control without requiring excessive coding overhead or decoding time. In LSI and VLSI technology, memories are often organized on a multiple bit (or byte) per chip basis. For example, some 256K-bit DRAM's are organized in 32Kx8 bit-bytes. Byte oriented codes such as Reed Solomon (RS) codes can provide efficient low overhead error control for such memories. However, the standard iterative algorithm for decoding RS codes is too slow for these applications. In this paper we present some special decoding techniques for extended single-and-double-error-correcting RS codes which are capable of high speed operation. These techniques are designed to find the error locations and the error values directly from the syndrome without having to use the iterative alorithm to find the error locator polynomial. Two codes are considered: (1) a d sub min = 4 single-byte-error-correcting (SBEC), double-byte-error-detecting (DBED) RS code; and (2) a d sub min = 6 double-byte-error-correcting (DBEC), triple-byte-error-detecting (TBED) RS code.

Use of units of measurement error in anthropometric comparisons.

PubMed

Lucas, Teghan; Henneberg, Maciej

2017-09-01

Anthropometrists attempt to minimise measurement errors, however, errors cannot be eliminated entirely. Currently, measurement errors are simply reported. Measurement errors should be included into analyses of anthropometric data. This study proposes a method which incorporates measurement errors into reported values, replacing metric units with 'units of technical error of measurement (TEM)' by applying these to forensics, industrial anthropometry and biological variation. The USA armed forces anthropometric survey (ANSUR) contains 132 anthropometric dimensions of 3982 individuals. Concepts of duplication and Euclidean distance calculations were applied to the forensic-style identification of individuals in this survey. The National Size and Shape Survey of Australia contains 65 anthropometric measurements of 1265 women. This sample was used to show how a woman's body measurements expressed in TEM could be 'matched' to standard clothing sizes. Euclidean distances show that two sets of repeated anthropometric measurements of the same person cannot be matched (> 0) on measurements expressed in millimetres but can in units of TEM (= 0). Only 81 women can fit into any standard clothing size when matched using centimetres, with units of TEM, 1944 women fit. The proposed method can be applied to all fields that use anthropometry. Units of TEM are considered a more reliable unit of measurement for comparisons.

Conditional Standard Errors of Measurement for Scale Scores.

ERIC Educational Resources Information Center

Kolen, Michael J.; And Others

1992-01-01

A procedure is described for estimating the reliability and conditional standard errors of measurement of scale scores incorporating the discrete transformation of raw scores to scale scores. The method is illustrated using a strong true score model, and practical applications are described. (SLD)

Rectifying calibration error of Goldmann applanation tonometer is easy!

PubMed

Choudhari, Nikhil S; Moorthy, Krishna P; Tungikar, Vinod B; Kumar, Mohan; George, Ronnie; Rao, Harsha L; Senthil, Sirisha; Vijaya, Lingam; Garudadri, Chandra Sekhar

2014-11-01

Purpose: Goldmann applanation tonometer (GAT) is the current Gold standard tonometer. However, its calibration error is common and can go unnoticed in clinics. Its company repair has limitations. The purpose of this report is to describe a self-taught technique of rectifying calibration error of GAT. Materials and Methods: Twenty-nine slit-lamp-mounted Haag-Streit Goldmann tonometers (Model AT 900 C/M; Haag-Streit, Switzerland) were included in this cross-sectional interventional pilot study. The technique of rectification of calibration error of the tonometer involved cleaning and lubrication of the instrument followed by alignment of weights when lubrication alone didn't suffice. We followed the South East Asia Glaucoma Interest Group's definition of calibration error tolerance (acceptable GAT calibration error within ±2, ±3 and ±4 mm Hg at the 0, 20 and 60-mm Hg testing levels, respectively). Results: Twelve out of 29 (41.3%) GATs were out of calibration. The range of positive and negative calibration error at the clinically most important 20-mm Hg testing level was 0.5 to 20 mm Hg and -0.5 to -18 mm Hg, respectively. Cleaning and lubrication alone sufficed to rectify calibration error of 11 (91.6%) faulty instruments. Only one (8.3%) faulty GAT required alignment of the counter-weight. Conclusions: Rectification of calibration error of GAT is possible in-house. Cleaning and lubrication of GAT can be carried out even by eye care professionals and may suffice to rectify calibration error in the majority of faulty instruments. Such an exercise may drastically reduce the downtime of the Gold standard tonometer.

Cost-effectiveness of the stream-gaging program in Kentucky

USGS Publications Warehouse

Ruhl, K.J.

1989-01-01

This report documents the results of a study of the cost-effectiveness of the stream-gaging program in Kentucky. The total surface-water program includes 97 daily-discharge stations , 12 stage-only stations, and 35 crest-stage stations and is operated on a budget of $950,700. One station used for research lacks adequate source of funding and should be discontinued when the research ends. Most stations in the network are multiple-use with 65 stations operated for the purpose of defining hydrologic systems, 48 for project operation, 47 for definition of regional hydrology, and 43 for hydrologic forecasting purposes. Eighteen stations support water quality monitoring activities, one station is used for planning and design, and one station is used for research. The average standard error of estimation of streamflow records was determined only for stations in the Louisville Subdistrict. Under current operating policy, with a budget of $223,500, the average standard error of estimation is 28.5%. Altering the travel routes and measurement frequency to reduce the amount of lost stage record would allow a slight decrease in standard error to 26.9%. The results indicate that the collection of streamflow records in the Louisville Subdistrict is cost effective in its present mode of operation. In the Louisville Subdistrict, a minimum budget of $214,200 is required to operate the current network at an average standard error of 32.7%. A budget less than this does not permit proper service and maintenance of the gages and recorders. The maximum budget analyzed was $268,200, which would result in an average standard error of 16.9% indicating that if the budget was increased by 20%, the percent standard error would be reduced 40 %. (USGS)

Effectiveness of Toyota process redesign in reducing thyroid gland fine-needle aspiration error.

PubMed

Raab, Stephen S; Grzybicki, Dana Marie; Sudilovsky, Daniel; Balassanian, Ronald; Janosky, Janine E; Vrbin, Colleen M

2006-10-01

Our objective was to determine whether the Toyota Production System process redesign resulted in diagnostic error reduction for patients who underwent cytologic evaluation of thyroid nodules. In this longitudinal, nonconcurrent cohort study, we compared the diagnostic error frequency of a thyroid aspiration service before and after implementation of error reduction initiatives consisting of adoption of a standardized diagnostic terminology scheme and an immediate interpretation service. A total of 2,424 patients underwent aspiration. Following terminology standardization, the false-negative rate decreased from 41.8% to 19.1% (P = .006), the specimen nondiagnostic rate increased from 5.8% to 19.8% (P < .001), and the sensitivity increased from 70.2% to 90.6% (P < .001). Cases with an immediate interpretation had a lower noninterpretable specimen rate than those without immediate interpretation (P < .001). Toyota process change led to significantly fewer diagnostic errors for patients who underwent thyroid fine-needle aspiration.

An Empirical State Error Covariance Matrix for Batch State Estimation

NASA Technical Reports Server (NTRS)

Frisbee, Joseph H., Jr.

2011-01-01

State estimation techniques serve effectively to provide mean state estimates. However, the state error covariance matrices provided as part of these techniques suffer from some degree of lack of confidence in their ability to adequately describe the uncertainty in the estimated states. A specific problem with the traditional form of state error covariance matrices is that they represent only a mapping of the assumed observation error characteristics into the state space. Any errors that arise from other sources (environment modeling, precision, etc.) are not directly represented in a traditional, theoretical state error covariance matrix. Consider that an actual observation contains only measurement error and that an estimated observation contains all other errors, known and unknown. It then follows that a measurement residual (the difference between expected and observed measurements) contains all errors for that measurement. Therefore, a direct and appropriate inclusion of the actual measurement residuals in the state error covariance matrix will result in an empirical state error covariance matrix. This empirical state error covariance matrix will fully account for the error in the state estimate. By way of a literal reinterpretation of the equations involved in the weighted least squares estimation algorithm, it is possible to arrive at an appropriate, and formally correct, empirical state error covariance matrix. The first specific step of the method is to use the average form of the weighted measurement residual variance performance index rather than its usual total weighted residual form. Next it is helpful to interpret the solution to the normal equations as the average of a collection of sample vectors drawn from a hypothetical parent population. From here, using a standard statistical analysis approach, it directly follows as to how to determine the standard empirical state error covariance matrix. This matrix will contain the total uncertainty in the state estimate, regardless as to the source of the uncertainty. Also, in its most straight forward form, the technique only requires supplemental calculations to be added to existing batch algorithms. The generation of this direct, empirical form of the state error covariance matrix is independent of the dimensionality of the observations. Mixed degrees of freedom for an observation set are allowed. As is the case with any simple, empirical sample variance problems, the presented approach offers an opportunity (at least in the case of weighted least squares) to investigate confidence interval estimates for the error covariance matrix elements. The diagonal or variance terms of the error covariance matrix have a particularly simple form to associate with either a multiple degree of freedom chi-square distribution (more approximate) or with a gamma distribution (less approximate). The off diagonal or covariance terms of the matrix are less clear in their statistical behavior. However, the off diagonal covariance matrix elements still lend themselves to standard confidence interval error analysis. The distributional forms associated with the off diagonal terms are more varied and, perhaps, more approximate than those associated with the diagonal terms. Using a simple weighted least squares sample problem, results obtained through use of the proposed technique are presented. The example consists of a simple, two observer, triangulation problem with range only measurements. Variations of this problem reflect an ideal case (perfect knowledge of the range errors) and a mismodeled case (incorrect knowledge of the range errors).

Use of Positive Blood Cultures for Direct Identification and Susceptibility Testing with the Vitek 2 System

PubMed Central

de Cueto, Marina; Ceballos, Esther; Martinez-Martinez, Luis; Perea, Evelio J.; Pascual, Alvaro

2004-01-01

In order to further decrease the time lapse between initial inoculation of blood culture media and the reporting of results of identification and antimicrobial susceptibility tests for microorganisms causing bacteremia, we performed a prospective study in which specially processed fluid from positive blood culture bottles from Bactec 9240 (Becton Dickinson, Cockeysville, Md.) containing aerobic media were directly inoculated into Vitek 2 system cards (bio-Mérieux, France). Organism identification and susceptibility results were compared with those obtained from cards inoculated with a standardized bacterial suspension obtained following subculture to agar; 100 consecutive positive monomicrobic blood cultures, consisting of 50 gram-negative rods and 50 gram-positive cocci, were included in the study. For gram-negative organisms, 31 of the 50 (62%) showed complete agreement with the standard method for species identification, while none of the 50 gram-positive cocci were correctly identified by the direct method. For gram-negative rods, there were 50% categorical agreements between the direct and standard methods for all drugs tested. The very major error rate was 2.4%, and the major error rate was 0.6%. The overall error rate for gram-negatives was 6.6%. Complete agreement in clinical categories of all antimicrobial agents evaluated was obtained for 19 of 50 (38%) gram-positive cocci evaluated; the overall error rate was 8.4%, with 2.8% minor errors, 2.4% major errors, and 3.2% very major errors. These findings suggest that the Vitek 2 cards inoculated directly from positive Bactec 9240 bottles do not provide acceptable bacterial identification or susceptibility testing in comparison with corresponding cards tested by a standard method. PMID:15297523

[The quality of medication orders--can it be improved?].

PubMed

Vaknin, Ofra; Wingart-Emerel, Efrat; Stern, Zvi

2003-07-01

Medication errors are a common cause of morbidity and mortality among patients. Medication administration in hospitals is a complicated procedure with the possibility of error at each step. Errors are most commonly found at the prescription and transcription stages, although it is known that most errors can easily be avoided through strict adherence to standardized procedure guidelines. In examination of medication errors reported in the hospital in the year 2000, we found that 38% reported to have resulted from transcription errors. In the year 2001, the hospital initiated a program designed to identify faulty process of orders in an effort to improve the quality and effectiveness of the medication administration process. As part of this program, it was decided to check and evaluate the quality of the written doctor's orders and the transcription of those orders to the nursing cadre, in various hospital units. The study was conducted using a questionnaire which checked compliance to hospital standards with regard to the medication administration process, as applied to 6 units over the course of 8 weeks. Results of the survey showed poor compliance to guidelines on the part of doctors and nurses. Only 18% of doctors' orders in the study and 37% of the nurses' transcriptions were written according to standards. The Emergency Department showed an even lower compliance with only 3% of doctors' orders and 25% of nurses' transcriptions complying to standards. As a result of this study, it was decided to initiate an intensive in-service teaching course to refresh the staff's knowledge of medication administration guidelines. In the future it is recommended that hand-written orders be replaced by computerized orders in an effort to limit the chance of error.

Onorbit IMU alignment error budget

NASA Technical Reports Server (NTRS)

Corson, R. W.

1980-01-01

The Star Tracker, Crew Optical Alignment Sight (COAS), and Inertial Measurement Unit (IMU) from a complex navigation system with a multitude of error sources were combined. A complete list of the system errors is presented. The errors were combined in a rational way to yield an estimate of the IMU alignment accuracy for STS-1. The expected standard deviation in the IMU alignment error for STS-1 type alignments was determined to be 72 arc seconds per axis for star tracker alignments and 188 arc seconds per axis for COAS alignments. These estimates are based on current knowledge of the star tracker, COAS, IMU, and navigation base error specifications, and were partially verified by preliminary Monte Carlo analysis.

General Aviation Avionics Statistics.

DTIC Science & Technology

1980-12-01

designed to produce standard errors on these variables at levels specified by the FAA. No controls were placed on the standard errors of the non-design...Transponder Encoding Requirement. and Mode CAutomatic (11as been deleted) Altitude Reporting Ca- pabili.,; Two-way Radio; VOR or TACAN Receiver. Remaining 42

First order error corrections in common introductory physics experiments

NASA Astrophysics Data System (ADS)

Beckey, Jacob; Baker, Andrew; Aravind, Vasudeva; Clarion Team

As a part of introductory physics courses, students perform different standard lab experiments. Almost all of these experiments are prone to errors owing to factors like friction, misalignment of equipment, air drag, etc. Usually these types of errors are ignored by students and not much thought is paid to the source of these errors. However, paying attention to these factors that give rise to errors help students make better physics models and understand physical phenomena behind experiments in more detail. In this work, we explore common causes of errors in introductory physics experiment and suggest changes that will mitigate the errors, or suggest models that take the sources of these errors into consideration. This work helps students build better and refined physical models and understand physics concepts in greater detail. We thank Clarion University undergraduate student grant for financial support involving this project.

Absolute color scale for improved diagnostics with wavefront error mapping.

PubMed

Smolek, Michael K; Klyce, Stephen D

2007-11-01

Wavefront data are expressed in micrometers and referenced to the pupil plane, but current methods to map wavefront error lack standardization. Many use normalized or floating scales that may confuse the user by generating ambiguous, noisy, or varying information. An absolute scale that combines consistent clinical information with statistical relevance is needed for wavefront error mapping. The color contours should correspond better to current corneal topography standards to improve clinical interpretation. Retrospective analysis of wavefront error data. Historic ophthalmic medical records. Topographic modeling system topographical examinations of 120 corneas across 12 categories were used. Corneal wavefront error data in micrometers from each topography map were extracted at 8 Zernike polynomial orders and for 3 pupil diameters expressed in millimeters (3, 5, and 7 mm). Both total aberrations (orders 2 through 8) and higher-order aberrations (orders 3 through 8) were expressed in the form of frequency histograms to determine the working range of the scale across all categories. The standard deviation of the mean error of normal corneas determined the map contour resolution. Map colors were based on corneal topography color standards and on the ability to distinguish adjacent color contours through contrast. Higher-order and total wavefront error contour maps for different corneal conditions. An absolute color scale was produced that encompassed a range of +/-6.5 microm and a contour interval of 0.5 microm. All aberrations in the categorical database were plotted with no loss of clinical information necessary for classification. In the few instances where mapped information was beyond the range of the scale, the type and severity of aberration remained legible. When wavefront data are expressed in micrometers, this absolute scale facilitates the determination of the severity of aberrations present compared with a floating scale, particularly for distinguishing normal from abnormal levels of wavefront error. The new color palette makes it easier to identify disorders. The corneal mapping method can be extended to mapping whole eye wavefront errors. When refraction data are expressed in diopters, the previously published corneal topography scale is suggested.

On a more rigorous gravity field processing for future LL-SST type gravity satellite missions

NASA Astrophysics Data System (ADS)

Daras, I.; Pail, R.; Murböck, M.

2013-12-01

In order to meet the augmenting demands of the user community concerning accuracies of temporal gravity field models, future gravity missions of low-low satellite-to-satellite tracking (LL-SST) type are planned to carry more precise sensors than their precedents. A breakthrough is planned with the improved LL-SST measurement link, where the traditional K-band microwave instrument of 1μm accuracy will be complemented by an inter-satellite ranging instrument of several nm accuracy. This study focuses on investigations concerning the potential performance of the new sensors and their impact in gravity field solutions. The processing methods for gravity field recovery have to meet the new sensor standards and be able to take full advantage of the new accuracies that they provide. We use full-scale simulations in a realistic environment to investigate whether the standard processing techniques suffice to fully exploit the new sensors standards. We achieve that by performing full numerical closed-loop simulations based on the Integral Equation approach. In our simulation scheme, we simulate dynamic orbits in a conventional tracking analysis to compute pseudo inter-satellite ranges or range-rates that serve as observables. Each part of the processing is validated separately with special emphasis on numerical errors and their impact in gravity field solutions. We demonstrate that processing with standard precision may be a limiting factor for taking full advantage of new generation sensors that future satellite missions will carry. Therefore we have created versions of our simulator with enhanced processing precision with primarily aim to minimize round-off system errors. Results using the enhanced precision show a big reduction of system errors that were present at the standard precision processing even for the error-free scenario, and reveal the improvements the new sensors will bring into the gravity field solutions. As a next step, we analyze the contribution of individual error sources to the system's error budget. More specifically we analyze sensor noise from the laser interferometer and the accelerometers, errors in the kinematic orbits and the background fields as well as temporal and spatial aliasing errors. We give special care on the assessment of error sources with stochastic behavior, such as the laser interferometer and the accelerometers, and their consistent stochastic modeling in frame of the adjustment process.

Analyzing communication errors in an air medical transport service.

PubMed

Dalto, Joseph D; Weir, Charlene; Thomas, Frank

2013-01-01

Poor communication can result in adverse events. Presently, no standards exist for classifying and analyzing air medical communication errors. This study sought to determine the frequency and types of communication errors reported within an air medical quality and safety assurance reporting system. Of 825 quality assurance reports submitted in 2009, 278 were randomly selected and analyzed for communication errors. Each communication error was classified and mapped to Clark's communication level hierarchy (ie, levels 1-4). Descriptive statistics were performed, and comparisons were evaluated using chi-square analysis. Sixty-four communication errors were identified in 58 reports (21% of 278). Of the 64 identified communication errors, only 18 (28%) were classified by the staff to be communication errors. Communication errors occurred most often at level 1 (n = 42/64, 66%) followed by level 4 (21/64, 33%). Level 2 and 3 communication failures were rare (, 1%). Communication errors were found in a fifth of quality and safety assurance reports. The reporting staff identified less than a third of these errors. Nearly all communication errors (99%) occurred at either the lowest level of communication (level 1, 66%) or the highest level (level 4, 33%). An air medical communication ontology is necessary to improve the recognition and analysis of communication errors. Copyright © 2013 Air Medical Journal Associates. Published by Elsevier Inc. All rights reserved.

An affordable cuff-less blood pressure estimation solution.

PubMed

Jain, Monika; Kumar, Niranjan; Deb, Sujay

2016-08-01

This paper presents a cuff-less hypertension pre-screening device that non-invasively monitors the Blood Pressure (BP) and Heart Rate (HR) continuously. The proposed device simultaneously records two clinically significant and highly correlated biomedical signals, viz., Electrocardiogram (ECG) and Photoplethysmogram (PPG). The device provides a common data acquisition platform that can interface with PC/laptop, Smart phone/tablet and Raspberry-pi etc. The hardware stores and processes the recorded ECG and PPG in order to extract the real-time BP and HR using kernel regression approach. The BP and HR estimation error is measured in terms of normalized mean square error, Error Standard Deviation (ESD) and Mean Absolute Error (MAE), with respect to a clinically proven digital BP monitor (OMRON HBP1300). The computed error falls under the maximum standard allowable error mentioned by Association for the Advancement of Medical Instrumentation; MAE <; 5 mmHg and ESD <; 8mmHg. The results are validated using two-tailed dependent sample t-test also. The proposed device is a portable low-cost home and clinic bases solution for continuous health monitoring.

Sample sizes needed for specified margins of relative error in the estimates of the repeatability and reproducibility standard deviations.

PubMed

McClure, Foster D; Lee, Jung K

2005-01-01

Sample size formulas are developed to estimate the repeatability and reproducibility standard deviations (Sr and S(R)) such that the actual error in (Sr and S(R)) relative to their respective true values, sigmar and sigmaR, are at predefined levels. The statistical consequences associated with AOAC INTERNATIONAL required sample size to validate an analytical method are discussed. In addition, formulas to estimate the uncertainties of (Sr and S(R)) were derived and are provided as supporting documentation. Formula for the Number of Replicates Required for a Specified Margin of Relative Error in the Estimate of the Repeatability Standard Deviation.

Outcomes of a Failure Mode and Effects Analysis for medication errors in pediatric anesthesia.

PubMed

Martin, Lizabeth D; Grigg, Eliot B; Verma, Shilpa; Latham, Gregory J; Rampersad, Sally E; Martin, Lynn D

2017-06-01

The Institute of Medicine has called for development of strategies to prevent medication errors, which are one important cause of preventable harm. Although the field of anesthesiology is considered a leader in patient safety, recent data suggest high medication error rates in anesthesia practice. Unfortunately, few error prevention strategies for anesthesia providers have been implemented. Using Toyota Production System quality improvement methodology, a multidisciplinary team observed 133 h of medication practice in the operating room at a tertiary care freestanding children's hospital. A failure mode and effects analysis was conducted to systematically deconstruct and evaluate each medication handling process step and score possible failure modes to quantify areas of risk. A bundle of five targeted countermeasures were identified and implemented over 12 months. Improvements in syringe labeling (73 to 96%), standardization of medication organization in the anesthesia workspace (0 to 100%), and two-provider infusion checks (23 to 59%) were observed. Medication error reporting improved during the project and was subsequently maintained. After intervention, the median medication error rate decreased from 1.56 to 0.95 per 1000 anesthetics. The frequency of medication error harm events reaching the patient also decreased. Systematic evaluation and standardization of medication handling processes by anesthesia providers in the operating room can decrease medication errors and improve patient safety. © 2017 John Wiley & Sons Ltd.

Quantifying uncertainty in carbon and nutrient pools of coarse woody debris

NASA Astrophysics Data System (ADS)

See, C. R.; Campbell, J. L.; Fraver, S.; Domke, G. M.; Harmon, M. E.; Knoepp, J. D.; Woodall, C. W.

2016-12-01

Woody detritus constitutes a major pool of both carbon and nutrients in forested ecosystems. Estimating coarse wood stocks relies on many assumptions, even when full surveys are conducted. Researchers rarely report error in coarse wood pool estimates, despite the importance to ecosystem budgets and modelling efforts. To date, no study has attempted a comprehensive assessment of error rates and uncertainty inherent in the estimation of this pool. Here, we use Monte Carlo analysis to propagate the error associated with the major sources of uncertainty present in the calculation of coarse wood carbon and nutrient (i.e., N, P, K, Ca, Mg, Na) pools. We also evaluate individual sources of error to identify the importance of each source of uncertainty in our estimates. We quantify sampling error by comparing the three most common field methods used to survey coarse wood (two transect methods and a whole-plot survey). We quantify the measurement error associated with length and diameter measurement, and technician error in species identification and decay class using plots surveyed by multiple technicians. We use previously published values of model error for the four most common methods of volume estimation: Smalian's, conical frustum, conic paraboloid, and average-of-ends. We also use previously published values for error in the collapse ratio (cross-sectional height/width) of decayed logs that serves as a surrogate for the volume remaining. We consider sampling error in chemical concentration and density for all decay classes, using distributions from both published and unpublished studies. Analytical uncertainty is calculated using standard reference plant material from the National Institute of Standards. Our results suggest that technician error in decay classification can have a large effect on uncertainty, since many of the error distributions included in the calculation (e.g. density, chemical concentration, volume-model selection, collapse ratio) are decay-class specific.

Bootstrap Estimates of Standard Errors in Generalizability Theory

ERIC Educational Resources Information Center

Tong, Ye; Brennan, Robert L.

2007-01-01

Estimating standard errors of estimated variance components has long been a challenging task in generalizability theory. Researchers have speculated about the potential applicability of the bootstrap for obtaining such estimates, but they have identified problems (especially bias) in using the bootstrap. Using Brennan's bias-correcting procedures…

Addressing Common Student Technical Errors in Field Data Collection: An Analysis of a Citizen-Science Monitoring Project.

PubMed

Philippoff, Joanna; Baumgartner, Erin

2016-03-01

The scientific value of citizen-science programs is limited when the data gathered are inconsistent, erroneous, or otherwise unusable. Long-term monitoring studies, such as Our Project In Hawai'i's Intertidal (OPIHI), have clear and consistent procedures and are thus a good model for evaluating the quality of participant data. The purpose of this study was to examine the kinds of errors made by student researchers during OPIHI data collection and factors that increase or decrease the likelihood of these errors. Twenty-four different types of errors were grouped into four broad error categories: missing data, sloppiness, methodological errors, and misidentification errors. "Sloppiness" was the most prevalent error type. Error rates decreased with field trip experience and student age. We suggest strategies to reduce data collection errors applicable to many types of citizen-science projects including emphasizing neat data collection, explicitly addressing and discussing the problems of falsifying data, emphasizing the importance of using standard scientific vocabulary, and giving participants multiple opportunities to practice to build their data collection techniques and skills.

Application of the precipitation-runoff modeling system to the Ah- shi-sle-pah Wash watershed, San Juan County, New Mexico

USGS Publications Warehouse

Hejl, H.R.

1989-01-01

The precipitation-runoff modeling system was applied to the 8.21 sq-mi drainage area of the Ah-shi-sle-pah Wash watershed in northwestern New Mexico. The calibration periods were May to September of 1981 and 1982, and the verification period was May to September 1983. Twelve storms were available for calibration and 8 storms were available for verification. For calibration A (hydraulic conductivity estimated from onsite data and other storm-mode parameters optimized), the computed standard error of estimate was 50% for runoff volumes and 72% of peak discharges. Calibration B included hydraulic conductivity in the optimization, which reduced the standard error of estimate to 28 % for runoff volumes and 50% for peak discharges. Optimized values for hydraulic conductivity resulted in reductions from 1.00 to 0.26 in/h and 0.20 to 0.03 in/h for the 2 general soils groups in the calibrations. Simulated runoff volumes using 7 of 8 storms occurring during the verification period had a standard error of estimate of 40% for verification A and 38% for verification B. Simulated peak discharge had a standard error of estimate of 120% for verification A and 56% for verification B. Including the eighth storm which had a relatively small magnitude in the verification analysis more than doubled the standard error of estimating volumes and peaks. (USGS)

Techniques for estimating monthly mean streamflow at gaged sites and monthly streamflow duration characteristics at ungaged sites in central Nevada

USGS Publications Warehouse

Hess, G.W.; Bohman, L.R.

1996-01-01

Techniques for estimating monthly mean streamflow at gaged sites and monthly streamflow duration characteristics at ungaged sites in central Nevada were developed using streamflow records at six gaged sites and basin physical and climatic characteristics. Streamflow data at gaged sites were related by regression techniques to concurrent flows at nearby gaging stations so that monthly mean streamflows for periods of missing or no record can be estimated for gaged sites in central Nevada. The standard error of estimate for relations at these sites ranged from 12 to 196 percent. Also, monthly streamflow data for selected percent exceedence levels were used in regression analyses with basin and climatic variables to determine relations for ungaged basins for annual and monthly percent exceedence levels. Analyses indicate that the drainage area and percent of drainage area at altitudes greater than 10,000 feet are the most significant variables. For the annual percent exceedence, the standard error of estimate of the relations for ungaged sites ranged from 51 to 96 percent and standard error of prediction for ungaged sites ranged from 96 to 249 percent. For the monthly percent exceedence values, the standard error of estimate of the relations ranged from 31 to 168 percent, and the standard error of prediction ranged from 115 to 3,124 percent. Reliability and limitations of the estimating methods are described.

The proposed coding standard at GSFC

NASA Technical Reports Server (NTRS)

Morakis, J. C.; Helgert, H. J.

1977-01-01

As part of the continuing effort to introduce standardization of spacecraft and ground equipment in satellite systems, NASA's Goddard Space Flight Center and other NASA facilities have supported the development of a set of standards for the use of error control coding in telemetry subsystems. These standards are intended to ensure compatibility between spacecraft and ground encoding equipment, while allowing sufficient flexibility to meet all anticipated mission requirements. The standards which have been developed to date cover the application of block codes in error detection and error correction modes, as well as short and long constraint length convolutional codes decoded via the Viterbi and sequential decoding algorithms, respectively. Included are detailed specifications of the codes, and their implementation. Current effort is directed toward the development of standards covering channels with burst noise characteristics, channels with feedback, and code concatenation.

Impact of Standardized Communication Techniques on Errors during Simulated Neonatal Resuscitation.

PubMed

Yamada, Nicole K; Fuerch, Janene H; Halamek, Louis P

2016-03-01

Current patterns of communication in high-risk clinical situations, such as resuscitation, are imprecise and prone to error. We hypothesized that the use of standardized communication techniques would decrease the errors committed by resuscitation teams during neonatal resuscitation. In a prospective, single-blinded, matched pairs design with block randomization, 13 subjects performed as a lead resuscitator in two simulated complex neonatal resuscitations. Two nurses assisted each subject during the simulated resuscitation scenarios. In one scenario, the nurses used nonstandard communication; in the other, they used standardized communication techniques. The performance of the subjects was scored to determine errors committed (defined relative to the Neonatal Resuscitation Program algorithm), time to initiation of positive pressure ventilation (PPV), and time to initiation of chest compressions (CC). In scenarios in which subjects were exposed to standardized communication techniques, there was a trend toward decreased error rate, time to initiation of PPV, and time to initiation of CC. While not statistically significant, there was a 1.7-second improvement in time to initiation of PPV and a 7.9-second improvement in time to initiation of CC. Should these improvements in human performance be replicated in the care of real newborn infants, they could improve patient outcomes and enhance patient safety. Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.

What to use to express the variability of data: Standard deviation or standard error of mean?

PubMed

Barde, Mohini P; Barde, Prajakt J

2012-07-01

Statistics plays a vital role in biomedical research. It helps present data precisely and draws the meaningful conclusions. While presenting data, one should be aware of using adequate statistical measures. In biomedical journals, Standard Error of Mean (SEM) and Standard Deviation (SD) are used interchangeably to express the variability; though they measure different parameters. SEM quantifies uncertainty in estimate of the mean whereas SD indicates dispersion of the data from mean. As readers are generally interested in knowing the variability within sample, descriptive data should be precisely summarized with SD. Use of SEM should be limited to compute CI which measures the precision of population estimate. Journals can avoid such errors by requiring authors to adhere to their guidelines.

Conditional standard errors of measurement for composite scores on the Wechsler Preschool and Primary Scale of Intelligence-Third Edition.

PubMed

Price, Larry R; Raju, Nambury; Lurie, Anna; Wilkins, Charles; Zhu, Jianjun

2006-02-01

A specific recommendation of the 1999 Standards for Educational and Psychological Testing by the American Educational Research Association, the American Psychological Association, and the National Council on Measurement in Education is that test publishers report estimates of the conditional standard error of measurement (SEM). Procedures for calculating the conditional (score-level) SEM based on raw scores are well documented; however, few procedures have been developed for estimating the conditional SEM of subtest or composite scale scores resulting from a nonlinear transformation. Item response theory provided the psychometric foundation to derive the conditional standard errors of measurement and confidence intervals for composite scores on the Wechsler Preschool and Primary Scale of Intelligence-Third Edition.

The impact of response measurement error on the analysis of designed experiments

DOE PAGES

Anderson-Cook, Christine Michaela; Hamada, Michael Scott; Burr, Thomas Lee

2016-11-01

This study considers the analysis of designed experiments when there is measurement error in the true response or so-called response measurement error. We consider both additive and multiplicative response measurement errors. Through a simulation study, we investigate the impact of ignoring the response measurement error in the analysis, that is, by using a standard analysis based on t-tests. In addition, we examine the role of repeat measurements in improving the quality of estimation and prediction in the presence of response measurement error. We also study a Bayesian approach that accounts for the response measurement error directly through the specification ofmore » the model, and allows including additional information about variability in the analysis. We consider the impact on power, prediction, and optimization. Copyright © 2015 John Wiley & Sons, Ltd.« less

The impact of response measurement error on the analysis of designed experiments

DOE Office of Scientific and Technical Information (OSTI.GOV)

Anderson-Cook, Christine Michaela; Hamada, Michael Scott; Burr, Thomas Lee

This study considers the analysis of designed experiments when there is measurement error in the true response or so-called response measurement error. We consider both additive and multiplicative response measurement errors. Through a simulation study, we investigate the impact of ignoring the response measurement error in the analysis, that is, by using a standard analysis based on t-tests. In addition, we examine the role of repeat measurements in improving the quality of estimation and prediction in the presence of response measurement error. We also study a Bayesian approach that accounts for the response measurement error directly through the specification ofmore » the model, and allows including additional information about variability in the analysis. We consider the impact on power, prediction, and optimization. Copyright © 2015 John Wiley & Sons, Ltd.« less

Restrictions on surgical resident shift length does not impact type of medical errors.

PubMed

Anderson, Jamie E; Goodman, Laura F; Jensen, Guy W; Salcedo, Edgardo S; Galante, Joseph M

2017-05-15

In 2011, resident duty hours were restricted in an attempt to improve patient safety and resident education. With the goal of reducing fatigue, shorter shift length leads to more patient handoffs, raising concerns about adverse effects on patient safety. This study seeks to determine whether differences in duty-hour restrictions influence types of errors made by residents. This is a nested retrospective cohort study at a surgery department in an academic medical center. During 2013-14, standard 2011 duty hours were in place for residents. In 2014-15, duty-hour restrictions at the study site were relaxed ("flexible") with no restrictions on shift length. We reviewed all morbidity and mortality submissions from July 1, 2013-June 30, 2015 and compared differences in types of errors between these periods. A total of 383 patients experienced adverse events, including 59 deaths (15.4%). Comparing standard versus flexible periods, there was no difference in mortality (15.7% versus 12.6%, P = 0.479) or complication rates (2.6% versus 2.5%, P = 0.696). There was no difference in types of errors between periods (P = 0.050-0.808). The most number of errors were due to cognitive failures (229, 59.6%), whereas the fewest number of errors were due to team failure (127, 33.2%). By subset, technical errors resulted in the highest number of errors (169, 44.1%). There were no differences between types of errors of cases that were nonelective, at night, or involving residents. Among adverse events reported in this departmental surgical morbidity and mortality, there were no differences in types of errors when resident duty hours were less restrictive. Copyright © 2017 Elsevier Inc. All rights reserved.

Comparison of Efficiency of Jackknife and Variance Component Estimators of Standard Errors. Program Statistics Research. Technical Report.

ERIC Educational Resources Information Center

Longford, Nicholas T.

Large scale surveys usually employ a complex sampling design and as a consequence, no standard methods for estimation of the standard errors associated with the estimates of population means are available. Resampling methods, such as jackknife or bootstrap, are often used, with reference to their properties of robustness and reduction of bias. A…

Errors in quantitative backscattered electron analysis of bone standardized by energy-dispersive x-ray spectrometry.

PubMed

Vajda, E G; Skedros, J G; Bloebaum, R D

1998-10-01

Backscattered electron (BSE) imaging has proven to be a useful method for analyzing the mineral distribution in microscopic regions of bone. However, an accepted method of standardization has not been developed, limiting the utility of BSE imaging for truly quantitative analysis. Previous work has suggested that BSE images can be standardized by energy-dispersive x-ray spectrometry (EDX). Unfortunately, EDX-standardized BSE images tend to underestimate the mineral content of bone when compared with traditional ash measurements. The goal of this study is to investigate the nature of the deficit between EDX-standardized BSE images and ash measurements. A series of analytical standards, ashed bone specimens, and unembedded bone specimens were investigated to determine the source of the deficit previously reported. The primary source of error was found to be inaccurate ZAF corrections to account for the organic phase of the bone matrix. Conductive coatings, methylmethacrylate embedding media, and minor elemental constituents in bone mineral introduced negligible errors. It is suggested that the errors would remain constant and an empirical correction could be used to account for the deficit. However, extensive preliminary testing of the analysis equipment is essential.

Stabilizing Conditional Standard Errors of Measurement in Scale Score Transformations

ERIC Educational Resources Information Center

Moses, Tim; Kim, YoungKoung

2017-01-01

The focus of this article is on scale score transformations that can be used to stabilize conditional standard errors of measurement (CSEMs). Three transformations for stabilizing the estimated CSEMs are reviewed, including the traditional arcsine transformation, a recently developed general variance stabilization transformation, and a new method…

WASP (Write a Scientific Paper) using Excel - 6: Standard error and confidence interval.

PubMed

Grech, Victor

2018-03-01

The calculation of descriptive statistics includes the calculation of standard error and confidence interval, an inevitable component of data analysis in inferential statistics. This paper provides pointers as to how to do this in Microsoft Excel™. Copyright © 2018 Elsevier B.V. All rights reserved.

Determinants of Standard Errors of MLEs in Confirmatory Factor Analysis

ERIC Educational Resources Information Center

Yuan, Ke-Hai; Cheng, Ying; Zhang, Wei

2010-01-01

This paper studies changes of standard errors (SE) of the normal-distribution-based maximum likelihood estimates (MLE) for confirmatory factor models as model parameters vary. Using logical analysis, simplified formulas and numerical verification, monotonic relationships between SEs and factor loadings as well as unique variances are found.…

Errors from approximation of ODE systems with reduced order models

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vassilevska, Tanya

2016-12-30

This is a code to calculate the error from approximation of systems of ordinary differential equations (ODEs) by using Proper Orthogonal Decomposition (POD) Reduced Order Models (ROM) methods and to compare and analyze the errors for two POD ROM variants. The first variant is the standard POD ROM, the second variant is a modification of the method using the values of the time derivatives (a.k.a. time-derivative snapshots). The code compares the errors from the two variants under different conditions.

MASTER: a model to improve and standardize clinical breakpoints for antimicrobial susceptibility testing using forecast probabilities.

PubMed

Blöchliger, Nicolas; Keller, Peter M; Böttger, Erik C; Hombach, Michael

2017-09-01

The procedure for setting clinical breakpoints (CBPs) for antimicrobial susceptibility has been poorly standardized with respect to population data, pharmacokinetic parameters and clinical outcome. Tools to standardize CBP setting could result in improved antibiogram forecast probabilities. We propose a model to estimate probabilities for methodological categorization errors and defined zones of methodological uncertainty (ZMUs), i.e. ranges of zone diameters that cannot reliably be classified. The impact of ZMUs on methodological error rates was used for CBP optimization. The model distinguishes theoretical true inhibition zone diameters from observed diameters, which suffer from methodological variation. True diameter distributions are described with a normal mixture model. The model was fitted to observed inhibition zone diameters of clinical Escherichia coli strains. Repeated measurements for a quality control strain were used to quantify methodological variation. For 9 of 13 antibiotics analysed, our model predicted error rates of < 0.1% applying current EUCAST CBPs. Error rates were > 0.1% for ampicillin, cefoxitin, cefuroxime and amoxicillin/clavulanic acid. Increasing the susceptible CBP (cefoxitin) and introducing ZMUs (ampicillin, cefuroxime, amoxicillin/clavulanic acid) decreased error rates to < 0.1%. ZMUs contained low numbers of isolates for ampicillin and cefuroxime (3% and 6%), whereas the ZMU for amoxicillin/clavulanic acid contained 41% of all isolates and was considered not practical. We demonstrate that CBPs can be improved and standardized by minimizing methodological categorization error rates. ZMUs may be introduced if an intermediate zone is not appropriate for pharmacokinetic/pharmacodynamic or drug dosing reasons. Optimized CBPs will provide a standardized antibiotic susceptibility testing interpretation at a defined level of probability. © The Author 2017. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Cost-effectiveness of the Federal stream-gaging program in Virginia

USGS Publications Warehouse

Carpenter, D.H.

1985-01-01

Data uses and funding sources were identified for the 77 continuous stream gages currently being operated in Virginia by the U.S. Geological Survey with a budget of $446,000. Two stream gages were identified as not being used sufficiently to warrant continuing their operation. Operation of these stations should be considered for discontinuation. Data collected at two other stations were identified as having uses primarily related to short-term studies; these stations should also be considered for discontinuation at the end of the data collection phases of the studies. The remaining 73 stations should be kept in the program for the foreseeable future. The current policy for operation of the 77-station program requires a budget of $446,000/yr. The average standard error of estimation of streamflow records is 10.1%. It was shown that this overall level of accuracy at the 77 sites could be maintained with a budget of $430,500 if resources were redistributed among the gages. A minimum budget of $428,500 is required to operate the 77-gage program; a smaller budget would not permit proper service and maintenance of the gages and recorders. At the minimum budget, with optimized operation, the average standard error would be 10.4%. The maximum budget analyzed was $650,000, which resulted in an average standard error of 5.5%. The study indicates that a major component of error is caused by lost or missing data. If perfect equipment were available, the standard error for the current program and budget could be reduced to 7.6%. This also can be interpreted to mean that the streamflow data have a standard error of this magnitude during times when the equipment is operating properly. (Author 's abstract)

Panel positioning error and support mechanism for a 30-m THz radio telescope

NASA Astrophysics Data System (ADS)

Yang, De-Hua; Okoh, Daniel; Zhou, Guo-Hua; Li, Ai-Hua; Li, Guo-Ping; Cheng, Jing-Quan

2011-06-01

A 30-m TeraHertz (THz) radio telescope is proposed to operate at 200 μm with an active primary surface. This paper presents sensitivity analysis of active surface panel positioning errors with optical performance in terms of the Strehl ratio. Based on Ruze's surface error theory and using a Monte Carlo simulation, the effects of six rigid panel positioning errors, such as piston, tip, tilt, radial, azimuthal and twist displacements, were directly derived. The optical performance of the telescope was then evaluated using the standard Strehl ratio. We graphically illustrated the various panel error effects by presenting simulations of complete ensembles of full reflector surface errors for the six different rigid panel positioning errors. Study of the panel error sensitivity analysis revealed that the piston error and tilt/tip errors are dominant while the other rigid errors are much less important. Furthermore, as indicated by the results, we conceived of an alternative Master-Slave Concept-based (MSC-based) active surface by implementating a special Series-Parallel Concept-based (SPC-based) hexapod as the active panel support mechanism. A new 30-m active reflector based on the two concepts was demonstrated to achieve correction for all the six rigid panel positioning errors in an economically feasible way.

FipsOrtho: A Spell Checker for Learners of French

ERIC Educational Resources Information Center

L'Haire, Sebastien

2007-01-01

This paper presents FipsOrtho, a spell checker targeted at learners of French, and a corpus of learners' errors which has been gathered to test the system and to get a sample of specific language learners' errors. Spell checkers are a standard feature of many software products, however they are not designed for specific language learners' errors.…

Conditional Standard Errors of Measurement for Composite Scores Using IRT

ERIC Educational Resources Information Center

Kolen, Michael J.; Wang, Tianyou; Lee, Won-Chan

2012-01-01

Composite scores are often formed from test scores on educational achievement test batteries to provide a single index of achievement over two or more content areas or two or more item types on that test. Composite scores are subject to measurement error, and as with scores on individual tests, the amount of error variability typically depends on…

Using Least Squares for Error Propagation

ERIC Educational Resources Information Center

Tellinghuisen, Joel

2015-01-01

The method of least-squares (LS) has a built-in procedure for estimating the standard errors (SEs) of the adjustable parameters in the fit model: They are the square roots of the diagonal elements of the covariance matrix. This means that one can use least-squares to obtain numerical values of propagated errors by defining the target quantities as…

End-of-Kindergarten Spelling Outcomes: How Can Spelling Error Analysis Data Inform Beginning Reading Instruction?

PubMed

Lee, Julia Ai Cheng; Otaiba, Stephanie Al

2017-01-01

In this article, the authors examined the spelling performance of 430 kindergarteners, which included a high risk sample, to determine the relations between end of kindergarten reading and spelling in a high quality language arts setting. The spelling outcomes including the spelling errors between the good and the poor readers were described, analyzed, and compared. The findings suggest that not all the children have acquired the desired standard as outlined by the Common Core State Standards. In addition, not every good reader is a good speller and that not every poor speller is a poor reader. The study shows that spelling tasks that are accompanied by spelling errors analysis provide a powerful window for making instructional sense of children's spelling errors and for individualizing spelling instructional strategies.

Role of memory errors in quantum repeaters

NASA Astrophysics Data System (ADS)

Hartmann, L.; Kraus, B.; Briegel, H.-J.; Dür, W.

2007-03-01

We investigate the influence of memory errors in the quantum repeater scheme for long-range quantum communication. We show that the communication distance is limited in standard operation mode due to memory errors resulting from unavoidable waiting times for classical signals. We show how to overcome these limitations by (i) improving local memory and (ii) introducing two operational modes of the quantum repeater. In both operational modes, the repeater is run blindly, i.e., without waiting for classical signals to arrive. In the first scheme, entanglement purification protocols based on one-way classical communication are used allowing to communicate over arbitrary distances. However, the error thresholds for noise in local control operations are very stringent. The second scheme makes use of entanglement purification protocols with two-way classical communication and inherits the favorable error thresholds of the repeater run in standard mode. One can increase the possible communication distance by an order of magnitude with reasonable overhead in physical resources. We outline the architecture of a quantum repeater that can possibly ensure intercontinental quantum communication.

Error simulation of paired-comparison-based scaling methods

NASA Astrophysics Data System (ADS)

Cui, Chengwu

2000-12-01

Subjective image quality measurement usually resorts to psycho physical scaling. However, it is difficult to evaluate the inherent precision of these scaling methods. Without knowing the potential errors of the measurement, subsequent use of the data can be misleading. In this paper, the errors on scaled values derived form paired comparison based scaling methods are simulated with randomly introduced proportion of choice errors that follow the binomial distribution. Simulation results are given for various combinations of the number of stimuli and the sampling size. The errors are presented in the form of average standard deviation of the scaled values and can be fitted reasonably well with an empirical equation that can be sued for scaling error estimation and measurement design. The simulation proves paired comparison based scaling methods can have large errors on the derived scaled values when the sampling size and the number of stimuli are small. Examples are also given to show the potential errors on actually scaled values of color image prints as measured by the method of paired comparison.

Intervention strategies for the management of human error

NASA Technical Reports Server (NTRS)

Wiener, Earl L.

1993-01-01

This report examines the management of human error in the cockpit. The principles probably apply as well to other applications in the aviation realm (e.g. air traffic control, dispatch, weather, etc.) as well as other high-risk systems outside of aviation (e.g. shipping, high-technology medical procedures, military operations, nuclear power production). Management of human error is distinguished from error prevention. It is a more encompassing term, which includes not only the prevention of error, but also a means of disallowing an error, once made, from adversely affecting system output. Such techniques include: traditional human factors engineering, improvement of feedback and feedforward of information from system to crew, 'error-evident' displays which make erroneous input more obvious to the crew, trapping of errors within a system, goal-sharing between humans and machines (also called 'intent-driven' systems), paperwork management, and behaviorally based approaches, including procedures, standardization, checklist design, training, cockpit resource management, etc. Fifteen guidelines for the design and implementation of intervention strategies are included.

Reed Solomon codes for error control in byte organized computer memory systems

NASA Technical Reports Server (NTRS)

Lin, S.; Costello, D. J., Jr.

1984-01-01

A problem in designing semiconductor memories is to provide some measure of error control without requiring excessive coding overhead or decoding time. In LSI and VLSI technology, memories are often organized on a multiple bit (or byte) per chip basis. For example, some 256K-bit DRAM's are organized in 32Kx8 bit-bytes. Byte oriented codes such as Reed Solomon (RS) codes can provide efficient low overhead error control for such memories. However, the standard iterative algorithm for decoding RS codes is too slow for these applications. Some special decoding techniques for extended single-and-double-error-correcting RS codes which are capable of high speed operation are presented. These techniques are designed to find the error locations and the error values directly from the syndrome without having to use the iterative algorithm to find the error locator polynomial.

The current and ideal state of anatomic pathology patient safety.

PubMed

Raab, Stephen Spencer

2014-01-01

An anatomic pathology diagnostic error may be secondary to a number of active and latent technical and/or cognitive components, which may occur anywhere along the total testing process in clinical and/or laboratory domains. For the pathologist interpretive steps of diagnosis, we examine Kahneman's framework of slow and fast thinking to explain different causes of error in precision (agreement) and in accuracy (truth). The pathologist cognitive diagnostic process involves image pattern recognition and a slow thinking error may be caused by the application of different rationally-constructed mental maps of image criteria/patterns by different pathologists. This type of error is partly related to a system failure in standardizing the application of these maps. A fast thinking error involves the flawed leap from image pattern to incorrect diagnosis. In the ideal state, anatomic pathology systems would target these cognitive error causes as well as the technical latent factors that lead to error.

Abnormal Error Monitoring in Math-Anxious Individuals: Evidence from Error-Related Brain Potentials

PubMed Central

Suárez-Pellicioni, Macarena; Núñez-Peña, María Isabel; Colomé, Àngels

2013-01-01

This study used event-related brain potentials to investigate whether math anxiety is related to abnormal error monitoring processing. Seventeen high math-anxious (HMA) and seventeen low math-anxious (LMA) individuals were presented with a numerical and a classical Stroop task. Groups did not differ in terms of trait or state anxiety. We found enhanced error-related negativity (ERN) in the HMA group when subjects committed an error on the numerical Stroop task, but not on the classical Stroop task. Groups did not differ in terms of the correct-related negativity component (CRN), the error positivity component (Pe), classical behavioral measures or post-error measures. The amplitude of the ERN was negatively related to participants’ math anxiety scores, showing a more negative amplitude as the score increased. Moreover, using standardized low resolution electromagnetic tomography (sLORETA) we found greater activation of the insula in errors on a numerical task as compared to errors in a non-numerical task only for the HMA group. The results were interpreted according to the motivational significance theory of the ERN. PMID:24236212

Composite Reliability and Standard Errors of Measurement for a Seven-Subtest Short Form of the Wechsler Adult Intelligence Scale-Revised.

ERIC Educational Resources Information Center

Schretlen, David; And Others

1994-01-01

Composite reliability and standard errors of measurement were computed for prorated Verbal, Performance, and Full-Scale intelligence quotient (IQ) scores from a seven-subtest short form of the Wechsler Adult Intelligence Scale-Revised. Results with 1,880 adults (standardization sample) indicate that this form is as reliable as the complete test.…

A Brief Look at: Test Scores and the Standard Error of Measurement. E&R Report No. 10.13

ERIC Educational Resources Information Center

Holdzkom, David; Sumner, Brian; McMillen, Brad

2010-01-01

In the context of standardized testing, the standard error of measurement (SEM) is a measure of the factors other than the student's actual knowledge of the tested material that may affect the student's test score. Such factors may include distractions in the testing environment, fatigue, hunger, or even luck. This means that a student's observed…

Bootstrap Standard Error Estimates in Dynamic Factor Analysis

ERIC Educational Resources Information Center

Zhang, Guangjian; Browne, Michael W.

2010-01-01

Dynamic factor analysis summarizes changes in scores on a battery of manifest variables over repeated measurements in terms of a time series in a substantially smaller number of latent factors. Algebraic formulae for standard errors of parameter estimates are more difficult to obtain than in the usual intersubject factor analysis because of the…

Standard Errors of Equating Differences: Prior Developments, Extensions, and Simulations

ERIC Educational Resources Information Center

Moses, Tim; Zhang, Wenmin

2011-01-01

The purpose of this article was to extend the use of standard errors for equated score differences (SEEDs) to traditional equating functions. The SEEDs are described in terms of their original proposal for kernel equating functions and extended so that SEEDs for traditional linear and traditional equipercentile equating functions can be computed.…

Progress in the improved lattice calculation of direct CP-violation in the Standard Model

NASA Astrophysics Data System (ADS)

Kelly, Christopher

2018-03-01

We discuss the ongoing effort by the RBC & UKQCD collaborations to improve our lattice calculation of the measure of Standard Model direct CP violation, ɛ', with physical kinematics. We present our progress in decreasing the (dominant) statistical error and discuss other related activities aimed at reducing the systematic errors.

The Development of MST Test Information for the Prediction of Test Performances

ERIC Educational Resources Information Center

Park, Ryoungsun; Kim, Jiseon; Chung, Hyewon; Dodd, Barbara G.

2017-01-01

The current study proposes novel methods to predict multistage testing (MST) performance without conducting simulations. This method, called MST test information, is based on analytic derivation of standard errors of ability estimates across theta levels. We compared standard errors derived analytically to the simulation results to demonstrate the…

Supplemental Figures, Tables, and Standard Error Tables for Student Financing of Undergraduate Education: 2007-08. Sticker, Net, and Out-of-Pocket Prices

ERIC Educational Resources Information Center

National Center for Education Statistics, 2010

2010-01-01

This paper presents the supplemental figures, tables, and standard error tables for the report "Student Financing of Undergraduate Education: 2007-08. Web Tables. NCES 2010-162." (Contains 6 figures and 10 tables.) [For the main report, see ED511828.

Mismeasurement and the resonance of strong confounders: correlated errors.

PubMed

Marshall, J R; Hastrup, J L; Ross, J S

1999-07-01

Confounding in epidemiology, and the limits of standard methods of control for an imperfectly measured confounder, have been understood for some time. However, most treatments of this problem are based on the assumption that errors of measurement in confounding and confounded variables are independent. This paper considers the situation in which a strong risk factor (confounder) and an inconsequential but suspected risk factor (confounded) are each measured with errors that are correlated; the situation appears especially likely to occur in the field of nutritional epidemiology. Error correlation appears to add little to measurement error as a source of bias in estimating the impact of a strong risk factor: it can add to, diminish, or reverse the bias induced by measurement error in estimating the impact of the inconsequential risk factor. Correlation of measurement errors can add to the difficulty involved in evaluating structures in which confounding and measurement error are present. In its presence, observed correlations among risk factors can be greater than, less than, or even opposite to the true correlations. Interpretation of multivariate epidemiologic structures in which confounding is likely requires evaluation of measurement error structures, including correlations among measurement errors.

Is comprehension necessary for error detection? A conflict-based account of monitoring in speech production

PubMed Central

Nozari, Nazbanou; Dell, Gary S.; Schwartz, Myrna F.

2011-01-01

Despite the existence of speech errors, verbal communication is successful because speakers can detect (and correct) their errors. The standard theory of speech-error detection, the perceptual-loop account, posits that the comprehension system monitors production output for errors. Such a comprehension-based monitor, however, cannot explain the double dissociation between comprehension and error-detection ability observed in the aphasic patients. We propose a new theory of speech-error detection which is instead based on the production process itself. The theory borrows from studies of forced-choice-response tasks the notion that error detection is accomplished by monitoring response conflict via a frontal brain structure, such as the anterior cingulate cortex. We adapt this idea to the two-step model of word production, and test the model-derived predictions on a sample of aphasic patients. Our results show a strong correlation between patients’ error-detection ability and the model’s characterization of their production skills, and no significant correlation between error detection and comprehension measures, thus supporting a production-based monitor, generally, and the implemented conflict-based monitor in particular. The successful application of the conflict-based theory to error-detection in linguistic, as well as non-linguistic domains points to a domain-general monitoring system. PMID:21652015

Comparative study of anatomical normalization errors in SPM and 3D-SSP using digital brain phantom.

PubMed

Onishi, Hideo; Matsutake, Yuki; Kawashima, Hiroki; Matsutomo, Norikazu; Amijima, Hizuru

2011-01-01

In single photon emission computed tomography (SPECT) cerebral blood flow studies, two major algorithms are widely used statistical parametric mapping (SPM) and three-dimensional stereotactic surface projections (3D-SSP). The aim of this study is to compare an SPM algorithm-based easy Z score imaging system (eZIS) and a 3D-SSP system in the errors of anatomical standardization using 3D-digital brain phantom images. We developed a 3D-brain digital phantom based on MR images to simulate the effects of head tilt, perfusion defective region size, and count value reduction rate on the SPECT images. This digital phantom was used to compare the errors of anatomical standardization by the eZIS and the 3D-SSP algorithms. While the eZIS allowed accurate standardization of the images of the phantom simulating a head in rotation, lateroflexion, anteflexion, or retroflexion without angle dependency, the standardization by 3D-SSP was not accurate enough at approximately 25° or more head tilt. When the simulated head contained perfusion defective regions, one of the 3D-SSP images showed an error of 6.9% from the true value. Meanwhile, one of the eZIS images showed an error as large as 63.4%, revealing a significant underestimation. When required to evaluate regions with decreased perfusion due to such causes as hemodynamic cerebral ischemia, the 3D-SSP is desirable. In a statistical image analysis, we must reconfirm the image after anatomical standardization by all means.

Cost effectiveness of the stream-gaging program in South Carolina

USGS Publications Warehouse

Barker, A.C.; Wright, B.C.; Bennett, C.S.

1985-01-01

The cost effectiveness of the stream-gaging program in South Carolina was documented for the 1983 water yr. Data uses and funding sources were identified for the 76 continuous stream gages currently being operated in South Carolina. The budget of $422,200 for collecting and analyzing streamflow data also includes the cost of operating stage-only and crest-stage stations. The streamflow records for one stream gage can be determined by alternate, less costly methods, and should be discontinued. The remaining 75 stations should be maintained in the program for the foreseeable future. The current policy for the operation of the 75 stations including the crest-stage and stage-only stations would require a budget of $417,200/yr. The average standard error of estimation of streamflow records is 16.9% for the present budget with missing record included. However, the standard error of estimation would decrease to 8.5% if complete streamflow records could be obtained. It was shown that the average standard error of estimation of 16.9% could be obtained at the 75 sites with a budget of approximately $395,000 if the gaging resources were redistributed among the gages. A minimum budget of $383,500 is required to operate the program; a budget less than this does not permit proper service and maintenance of the gages and recorders. At the minimum budget, the average standard error is 18.6%. The maximum budget analyzed was $850,000, which resulted in an average standard error of 7.6 %. (Author 's abstract)

Prevalence and risk factors of undercorrected refractive errors among Singaporean Malay adults: the Singapore Malay Eye Study.

PubMed

Rosman, Mohamad; Wong, Tien Y; Tay, Wan-Ting; Tong, Louis; Saw, Seang-Mei

2009-08-01

To describe the prevalence and the risk factors of undercorrected refractive error in an adult urban Malay population. This population-based, cross-sectional study was conducted in Singapore in 3280 Malay adults, aged 40 to 80 years. All individuals were examined at a centralized clinic and underwent standardized interviews and assessment of refractive errors and presenting and best corrected visual acuities. Distance presenting visual acuity was monocularly measured by using a logarithm of the minimum angle of resolution (logMAR) number chart at a distance of 4 m, with the participants wearing their "walk-in" optical corrections (spectacles or contact lenses), if any. Refraction was determined by subjective refraction by trained, certified study optometrists. Best corrected visual acuity was monocularly assessed and recorded in logMAR scores using the same test protocol as was used for presenting visual acuity. Undercorrected refractive error was defined as an improvement of at least 0.2 logMAR (2 lines equivalent) in the best corrected visual acuity compared with the presenting visual acuity in the better eye. The mean age of the subjects included in our study was 58 +/- 11 years, and 52% of the subjects were women. The prevalence rate of undercorrected refractive error among Singaporean Malay adults in our study (n = 3115) was 20.4% (age-standardized prevalence rate, 18.3%). More of the women had undercorrected refractive error than the men (21.8% vs. 18.8%, P = 0.04). Undercorrected refractive error was also more common in subjects older than 50 years than in subjects aged 40 to 49 years (22.6% vs. 14.3%, P < 0.001). Non-spectacle wearers were more likely to have undercorrected refractive errors than were spectacle wearers (24.4% vs. 14.4%, P < 0.001). Persons with primary school education or less were 1.89 times (P = 0.03) more likely to have undercorrected refractive errors than those with post-secondary school education or higher. In contrast, persons with a history of eye disease were 0.74 times (P = 0.003) less likely to have undercorrected refractive errors. The proportion of undercorrected refractive error among the Singaporean Malay adults with refractive errors was higher than that of the Singaporean Chinese adults with refractive errors. Undercorrected refractive error is a significant cause of correctable visual impairment among Singaporean Malay adults, affecting one in five persons.

Effect of grid transparency and finite collector size on determining ion temperature and density by the retarding potential analyzer

NASA Technical Reports Server (NTRS)

Troy, B. E., Jr.; Maier, E. J.

1975-01-01

The effects of the grid transparency and finite collector size on the values of thermal ion density and temperature determined by the standard RPA (retarding potential analyzer) analysis method are investigated. The current-voltage curves calculated for varying RPA parameters and a given ion mass, temperature, and density are analyzed by the standard RPA method. It is found that only small errors in temperature and density are introduced for an RPA with typical dimensions, and that even when the density error is substantial for nontypical dimensions, the temperature error remains minimum.

ASME B89.4.19 Performance Evaluation Tests and Geometric Misalignments in Laser Trackers

PubMed Central

Muralikrishnan, B.; Sawyer, D.; Blackburn, C.; Phillips, S.; Borchardt, B.; Estler, W. T.

2009-01-01

Small and unintended offsets, tilts, and eccentricity of the mechanical and optical components in laser trackers introduce systematic errors in the measured spherical coordinates (angles and range readings) and possibly in the calculated lengths of reference artifacts. It is desirable that the tests described in the ASME B89.4.19 Standard [1] be sensitive to these geometric misalignments so that any resulting systematic errors are identified during performance evaluation. In this paper, we present some analysis, using error models and numerical simulation, of the sensitivity of the length measurement system tests and two-face system tests in the B89.4.19 Standard to misalignments in laser trackers. We highlight key attributes of the testing strategy adopted in the Standard and propose new length measurement system tests that demonstrate improved sensitivity to some misalignments. Experimental results with a tracker that is not properly error corrected for the effects of the misalignments validate claims regarding the proposed new length tests. PMID:27504211

Analytical quality goals derived from the total deviation from patients' homeostatic set points, with a margin for analytical errors.

PubMed

Bolann, B J; Asberg, A

2004-01-01

The deviation of test results from patients' homeostatic set points in steady-state conditions may complicate interpretation of the results and the comparison of results with clinical decision limits. In this study the total deviation from the homeostatic set point is defined as the maximum absolute deviation for 95% of measurements, and we present analytical quality requirements that prevent analytical error from increasing this deviation to more than about 12% above the value caused by biology alone. These quality requirements are: 1) The stable systematic error should be approximately 0, and 2) a systematic error that will be detected by the control program with 90% probability, should not be larger than half the value of the combined analytical and intra-individual standard deviation. As a result, when the most common control rules are used, the analytical standard deviation may be up to 0.15 times the intra-individual standard deviation. Analytical improvements beyond these requirements have little impact on the interpretability of measurement results.

Using Audit Information to Adjust Parameter Estimates for Data Errors in Clinical Trials

PubMed Central

Shepherd, Bryan E.; Shaw, Pamela A.; Dodd, Lori E.

2013-01-01

Background Audits are often performed to assess the quality of clinical trial data, but beyond detecting fraud or sloppiness, the audit data is generally ignored. In earlier work using data from a non-randomized study, Shepherd and Yu (2011) developed statistical methods to incorporate audit results into study estimates, and demonstrated that audit data could be used to eliminate bias. Purpose In this manuscript we examine the usefulness of audit-based error-correction methods in clinical trial settings where a continuous outcome is of primary interest. Methods We demonstrate the bias of multiple linear regression estimates in general settings with an outcome that may have errors and a set of covariates for which some may have errors and others, including treatment assignment, are recorded correctly for all subjects. We study this bias under different assumptions including independence between treatment assignment, covariates, and data errors (conceivable in a double-blinded randomized trial) and independence between treatment assignment and covariates but not data errors (possible in an unblinded randomized trial). We review moment-based estimators to incorporate the audit data and propose new multiple imputation estimators. The performance of estimators is studied in simulations. Results When treatment is randomized and unrelated to data errors, estimates of the treatment effect using the original error-prone data (i.e., ignoring the audit results) are unbiased. In this setting, both moment and multiple imputation estimators incorporating audit data are more variable than standard analyses using the original data. In contrast, in settings where treatment is randomized but correlated with data errors and in settings where treatment is not randomized, standard treatment effect estimates will be biased. And in all settings, parameter estimates for the original, error-prone covariates will be biased. Treatment and covariate effect estimates can be corrected by incorporating audit data using either the multiple imputation or moment-based approaches. Bias, precision, and coverage of confidence intervals improve as the audit size increases. Limitations The extent of bias and the performance of methods depend on the extent and nature of the error as well as the size of the audit. This work only considers methods for the linear model. Settings much different than those considered here need further study. Conclusions In randomized trials with continuous outcomes and treatment assignment independent of data errors, standard analyses of treatment effects will be unbiased and are recommended. However, if treatment assignment is correlated with data errors or other covariates, naive analyses may be biased. In these settings, and when covariate effects are of interest, approaches for incorporating audit results should be considered. PMID:22848072

Using snowball sampling method with nurses to understand medication administration errors.

PubMed

Sheu, Shuh-Jen; Wei, Ien-Lan; Chen, Ching-Huey; Yu, Shu; Tang, Fu-In

2009-02-01

We aimed to encourage nurses to release information about drug administration errors to increase understanding of error-related circumstances and to identify high-alert situations. Drug administration errors represent the majority of medication errors, but errors are underreported. Effective ways are lacking to encourage nurses to actively report errors. Snowball sampling was conducted to recruit participants. A semi-structured questionnaire was used to record types of error, hospital and nurse backgrounds, patient consequences, error discovery mechanisms and reporting rates. Eighty-five nurses participated, reporting 328 administration errors (259 actual, 69 near misses). Most errors occurred in medical surgical wards of teaching hospitals, during day shifts, committed by nurses working fewer than two years. Leading errors were wrong drugs and doses, each accounting for about one-third of total errors. Among 259 actual errors, 83.8% resulted in no adverse effects; among remaining 16.2%, 6.6% had mild consequences and 9.6% had serious consequences (severe reaction, coma, death). Actual errors and near misses were discovered mainly through double-check procedures by colleagues and nurses responsible for errors; reporting rates were 62.5% (162/259) vs. 50.7% (35/69) and only 3.5% (9/259) vs. 0% (0/69) were disclosed to patients and families. High-alert situations included administration of 15% KCl, insulin and Pitocin; using intravenous pumps; and implementation of cardiopulmonary resuscitation (CPR). Snowball sampling proved to be an effective way to encourage nurses to release details concerning medication errors. Using empirical data, we identified high-alert situations. Strategies for reducing drug administration errors by nurses are suggested. Survey results suggest that nurses should double check medication administration in known high-alert situations. Nursing management can use snowball sampling to gather error details from nurses in a non-reprimanding atmosphere, helping to establish standard operational procedures for known high-alert situations.

[Errors in medicine. Causes, impact and improvement measures to improve patient safety].

PubMed

Waeschle, R M; Bauer, M; Schmidt, C E

2015-09-01

The guarantee of quality of care and patient safety is of major importance in hospitals even though increased economic pressure and work intensification are ubiquitously present. Nevertheless, adverse events still occur in 3-4 % of hospital stays and of these 25-50 % are estimated to be avoidable. The identification of possible causes of error and the development of measures for the prevention of medical errors are essential for patient safety. The implementation and continuous development of a constructive culture of error tolerance are fundamental.The origins of errors can be differentiated into systemic latent and individual active causes and components of both categories are typically involved when an error occurs. Systemic causes are, for example out of date structural environments, lack of clinical standards and low personnel density. These causes arise far away from the patient, e.g. management decisions and can remain unrecognized for a long time. Individual causes involve, e.g. confirmation bias, error of fixation and prospective memory failure. These causes have a direct impact on patient care and can result in immediate injury to patients. Stress, unclear information, complex systems and a lack of professional experience can promote individual causes. Awareness of possible causes of error is a fundamental precondition to establishing appropriate countermeasures.Error prevention should include actions directly affecting the causes of error and includes checklists and standard operating procedures (SOP) to avoid fixation and prospective memory failure and team resource management to improve communication and the generation of collective mental models. Critical incident reporting systems (CIRS) provide the opportunity to learn from previous incidents without resulting in injury to patients. Information technology (IT) support systems, such as the computerized physician order entry system, assist in the prevention of medication errors by providing information on dosage, pharmacological interactions, side effects and contraindications of medications.The major challenges for quality and risk management, for the heads of departments and the executive board is the implementation and support of the described actions and a sustained guidance of the staff involved in the modification management process. The global trigger tool is suitable for improving transparency and objectifying the frequency of medical errors.

Mimicking aphasic semantic errors in normal speech production: evidence from a novel experimental paradigm.

PubMed

Hodgson, Catherine; Lambon Ralph, Matthew A

2008-01-01

Semantic errors are commonly found in semantic dementia (SD) and some forms of stroke aphasia and provide insights into semantic processing and speech production. Low error rates are found in standard picture naming tasks in normal controls. In order to increase error rates and thus provide an experimental model of aphasic performance, this study utilised a novel method- tempo picture naming. Experiment 1 showed that, compared to standard deadline naming tasks, participants made more errors on the tempo picture naming tasks. Further, RTs were longer and more errors were produced to living items than non-living items a pattern seen in both semantic dementia and semantically-impaired stroke aphasic patients. Experiment 2 showed that providing the initial phoneme as a cue enhanced performance whereas providing an incorrect phonemic cue further reduced performance. These results support the contention that the tempo picture naming paradigm reduces the time allowed for controlled semantic processing causing increased error rates. This experimental procedure would, therefore, appear to mimic the performance of aphasic patients with multi-modal semantic impairment that results from poor semantic control rather than the degradation of semantic representations observed in semantic dementia [Jefferies, E. A., & Lambon Ralph, M. A. (2006). Semantic impairment in stoke aphasia vs. semantic dementia: A case-series comparison. Brain, 129, 2132-2147]. Further implications for theories of semantic cognition and models of speech processing are discussed.

Comparing biomarker measurements to a normal range: when to use standard error of the mean (SEM) or standard deviation (SD) confidence intervals tests.

PubMed

Pleil, Joachim D

2016-01-01

This commentary is the second of a series outlining one specific concept in interpreting biomarkers data. In the first, an observational method was presented for assessing the distribution of measurements before making parametric calculations. Here, the discussion revolves around the next step, the choice of using standard error of the mean or the calculated standard deviation to compare or predict measurement results.

Evaluating the prevalence and impact of examiner errors on the Wechsler scales of intelligence: A meta-analysis.

PubMed

Styck, Kara M; Walsh, Shana M

2016-01-01

The purpose of the present investigation was to conduct a meta-analysis of the literature on examiner errors for the Wechsler scales of intelligence. Results indicate that a mean of 99.7% of protocols contained at least 1 examiner error when studies that included a failure to record examinee responses as an error were combined and a mean of 41.2% of protocols contained at least 1 examiner error when studies that ignored errors of omission were combined. Furthermore, graduate student examiners were significantly more likely to make at least 1 error on Wechsler intelligence test protocols than psychologists. However, psychologists made significantly more errors per protocol than graduate student examiners regardless of the inclusion or exclusion of failure to record examinee responses as errors. On average, 73.1% of Full-Scale IQ (FSIQ) scores changed as a result of examiner errors, whereas 15.8%-77.3% of scores on the Verbal Comprehension Index (VCI), Perceptual Reasoning Index (PRI), Working Memory Index (WMI), and Processing Speed Index changed as a result of examiner errors. In addition, results suggest that examiners tend to overestimate FSIQ scores and underestimate VCI scores. However, no strong pattern emerged for the PRI and WMI. It can be concluded that examiner errors occur frequently and impact index and FSIQ scores. Consequently, current estimates for the standard error of measurement of popular IQ tests may not adequately capture the variance due to the examiner. (c) 2016 APA, all rights reserved).

Compensation of kinematic geometric parameters error and comparative study of accuracy testing for robot

NASA Astrophysics Data System (ADS)

Du, Liang; Shi, Guangming; Guan, Weibin; Zhong, Yuansheng; Li, Jin

2014-12-01

Geometric error is the main error of the industrial robot, and it plays a more significantly important fact than other error facts for robot. The compensation model of kinematic error is proposed in this article. Many methods can be used to test the robot accuracy, therefore, how to compare which method is better one. In this article, a method is used to compare two methods for robot accuracy testing. It used Laser Tracker System (LTS) and Three Coordinate Measuring instrument (TCM) to test the robot accuracy according to standard. According to the compensation result, it gets the better method which can improve the robot accuracy apparently.

Effects of Tropospheric Spatio-Temporal Correlated Noise on the Analysis of Space Geodetic Data

NASA Technical Reports Server (NTRS)

Romero-Wolf, A. F.; Jacobs, C. S.

2011-01-01

The standard VLBI analysis models measurement noise as purely thermal errors modeled according to uncorrelated Gaussian distributions. As the price of recording bits steadily decreases, thermal errors will soon no longer dominate. It is therefore expected that troposphere and instrumentation/clock errors will increasingly become more dominant. Given that both of these errors have correlated spectra, properly modeling the error distributions will become more relevant for optimal analysis. This paper will discuss the advantages of including the correlations between tropospheric delays using a Kolmogorov spectrum and the frozen ow model pioneered by Treuhaft and Lanyi. We will show examples of applying these correlated noise spectra to the weighting of VLBI data analysis.

Measurement errors in voice-key naming latency for Hiragana.

PubMed

Yamada, Jun; Tamaoka, Katsuo

2003-12-01

This study makes explicit the limitations and possibilities of voice-key naming latency research on single hiragana symbols (a Japanese syllabic script) by examining three sets of voice-key naming data against Sakuma, Fushimi, and Tatsumi's 1997 speech-analyzer voice-waveform data. Analysis showed that voice-key measurement errors can be substantial in standard procedures as they may conceal the true effects of significant variables involved in hiragana-naming behavior. While one can avoid voice-key measurement errors to some extent by applying Sakuma, et al.'s deltas and by excluding initial phonemes which induce measurement errors, such errors may be ignored when test items are words and other higher-level linguistic materials.

National suicide rates a century after Durkheim: do we know enough to estimate error?

PubMed

Claassen, Cynthia A; Yip, Paul S; Corcoran, Paul; Bossarte, Robert M; Lawrence, Bruce A; Currier, Glenn W

2010-06-01

Durkheim's nineteenth-century analysis of national suicide rates dismissed prior concerns about mortality data fidelity. Over the intervening century, however, evidence documenting various types of error in suicide data has only mounted, and surprising levels of such error continue to be routinely uncovered. Yet the annual suicide rate remains the most widely used population-level suicide metric today. After reviewing the unique sources of bias incurred during stages of suicide data collection and concatenation, we propose a model designed to uniformly estimate error in future studies. A standardized method of error estimation uniformly applied to mortality data could produce data capable of promoting high quality analyses of cross-national research questions.

Previous Estimates of Mitochondrial DNA Mutation Level Variance Did Not Account for Sampling Error: Comparing the mtDNA Genetic Bottleneck in Mice and Humans

PubMed Central

Wonnapinij, Passorn; Chinnery, Patrick F.; Samuels, David C.

2010-01-01

In cases of inherited pathogenic mitochondrial DNA (mtDNA) mutations, a mother and her offspring generally have large and seemingly random differences in the amount of mutated mtDNA that they carry. Comparisons of measured mtDNA mutation level variance values have become an important issue in determining the mechanisms that cause these large random shifts in mutation level. These variance measurements have been made with samples of quite modest size, which should be a source of concern because higher-order statistics, such as variance, are poorly estimated from small sample sizes. We have developed an analysis of the standard error of variance from a sample of size n, and we have defined error bars for variance measurements based on this standard error. We calculate variance error bars for several published sets of measurements of mtDNA mutation level variance and show how the addition of the error bars alters the interpretation of these experimental results. We compare variance measurements from human clinical data and from mouse models and show that the mutation level variance is clearly higher in the human data than it is in the mouse models at both the primary oocyte and offspring stages of inheritance. We discuss how the standard error of variance can be used in the design of experiments measuring mtDNA mutation level variance. Our results show that variance measurements based on fewer than 20 measurements are generally unreliable and ideally more than 50 measurements are required to reliably compare variances with less than a 2-fold difference. PMID:20362273

A visual detection model for DCT coefficient quantization

NASA Technical Reports Server (NTRS)

Ahumada, Albert J., Jr.; Watson, Andrew B.

1994-01-01

The discrete cosine transform (DCT) is widely used in image compression and is part of the JPEG and MPEG compression standards. The degree of compression and the amount of distortion in the decompressed image are controlled by the quantization of the transform coefficients. The standards do not specify how the DCT coefficients should be quantized. One approach is to set the quantization level for each coefficient so that the quantization error is near the threshold of visibility. Results from previous work are combined to form the current best detection model for DCT coefficient quantization noise. This model predicts sensitivity as a function of display parameters, enabling quantization matrices to be designed for display situations varying in luminance, veiling light, and spatial frequency related conditions (pixel size, viewing distance, and aspect ratio). It also allows arbitrary color space directions for the representation of color. A model-based method of optimizing the quantization matrix for an individual image was developed. The model described above provides visual thresholds for each DCT frequency. These thresholds are adjusted within each block for visual light adaptation and contrast masking. For given quantization matrix, the DCT quantization errors are scaled by the adjusted thresholds to yield perceptual errors. These errors are pooled nonlinearly over the image to yield total perceptual error. With this model one may estimate the quantization matrix for a particular image that yields minimum bit rate for a given total perceptual error, or minimum perceptual error for a given bit rate. Custom matrices for a number of images show clear improvement over image-independent matrices. Custom matrices are compatible with the JPEG standard, which requires transmission of the quantization matrix.

End-of-Kindergarten Spelling Outcomes: How Can Spelling Error Analysis Data Inform Beginning Reading Instruction?

PubMed Central

Lee, Julia Ai Cheng; Otaiba, Stephanie Al

2016-01-01

In this article, the authors examined the spelling performance of 430 kindergarteners, which included a high risk sample, to determine the relations between end of kindergarten reading and spelling in a high quality language arts setting. The spelling outcomes including the spelling errors between the good and the poor readers were described, analyzed, and compared. The findings suggest that not all the children have acquired the desired standard as outlined by the Common Core State Standards. In addition, not every good reader is a good speller and that not every poor speller is a poor reader. The study shows that spelling tasks that are accompanied by spelling errors analysis provide a powerful window for making instructional sense of children’s spelling errors and for individualizing spelling instructional strategies. PMID:28706433

A description of medication errors reported by pharmacists in a neonatal intensive care unit.

PubMed

Pawluk, Shane; Jaam, Myriam; Hazi, Fatima; Al Hail, Moza Sulaiman; El Kassem, Wessam; Khalifa, Hanan; Thomas, Binny; Abdul Rouf, Pallivalappila

2017-02-01

Background Patients in the Neonatal Intensive Care Unit (NICU) are at an increased risk for medication errors. Objective The objective of this study is to describe the nature and setting of medication errors occurring in patients admitted to an NICU in Qatar based on a standard electronic system reported by pharmacists. Setting Neonatal intensive care unit, Doha, Qatar. Method This was a retrospective cross-sectional study on medication errors reported electronically by pharmacists in the NICU between January 1, 2014 and April 30, 2015. Main outcome measure Data collected included patient information, and incident details including error category, medications involved, and follow-up completed. Results A total of 201 NICU pharmacists-reported medication errors were submitted during the study period. All reported errors did not reach the patient and did not cause harm. Of the errors reported, 98.5% occurred in the prescribing phase of the medication process with 58.7% being due to calculation errors. Overall, 53 different medications were documented in error reports with the anti-infective agents being the most frequently cited. The majority of incidents indicated that the primary prescriber was contacted and the error was resolved before reaching the next phase of the medication process. Conclusion Medication errors reported by pharmacists occur most frequently in the prescribing phase of the medication process. Our data suggest that error reporting systems need to be specific to the population involved. Special attention should be paid to frequently used medications in the NICU as these were responsible for the greatest numbers of medication errors.

Asymptotic Standard Errors for Item Response Theory True Score Equating of Polytomous Items

ERIC Educational Resources Information Center

Cher Wong, Cheow

2015-01-01

Building on previous works by Lord and Ogasawara for dichotomous items, this article proposes an approach to derive the asymptotic standard errors of item response theory true score equating involving polytomous items, for equivalent and nonequivalent groups of examinees. This analytical approach could be used in place of empirical methods like…

Standard Error Estimation of 3PL IRT True Score Equating with an MCMC Method

ERIC Educational Resources Information Center

Liu, Yuming; Schulz, E. Matthew; Yu, Lei

2008-01-01

A Markov chain Monte Carlo (MCMC) method and a bootstrap method were compared in the estimation of standard errors of item response theory (IRT) true score equating. Three test form relationships were examined: parallel, tau-equivalent, and congeneric. Data were simulated based on Reading Comprehension and Vocabulary tests of the Iowa Tests of…

How Accurate Is a Test Score?

ERIC Educational Resources Information Center

Doppelt, Jerome E.

1956-01-01

The standard error of measurement as a means for estimating the margin of error that should be allowed for in test scores is discussed. The true score measures the performance that is characteristic of the person tested; the variations, plus and minus, around the true score describe a characteristic of the test. When the standard deviation is used…

Standard Errors for National Trends in International Large-Scale Assessments in the Case of Cross-National Differential Item Functioning

ERIC Educational Resources Information Center

Sachse, Karoline A.; Haag, Nicole

2017-01-01

Standard errors computed according to the operational practices of international large-scale assessment studies such as the Programme for International Student Assessment's (PISA) or the Trends in International Mathematics and Science Study (TIMSS) may be biased when cross-national differential item functioning (DIF) and item parameter drift are…

Standard Error of Linear Observed-Score Equating for the NEAT Design with Nonnormally Distributed Data

ERIC Educational Resources Information Center

Zu, Jiyun; Yuan, Ke-Hai

2012-01-01

In the nonequivalent groups with anchor test (NEAT) design, the standard error of linear observed-score equating is commonly estimated by an estimator derived assuming multivariate normality. However, real data are seldom normally distributed, causing this normal estimator to be inconsistent. A general estimator, which does not rely on the…

Standard Errors of Estimated Latent Variable Scores with Estimated Structural Parameters

ERIC Educational Resources Information Center

Hoshino, Takahiro; Shigemasu, Kazuo

2008-01-01

The authors propose a concise formula to evaluate the standard error of the estimated latent variable score when the true values of the structural parameters are not known and must be estimated. The formula can be applied to factor scores in factor analysis or ability parameters in item response theory, without bootstrap or Markov chain Monte…

40 CFR 1065.1005 - Symbols, abbreviations, acronyms, and units of measure.

Code of Federal Regulations, 2014 CFR

2014-07-01

... of diameters meter per meter m/m 1 b atomic oxygen-to-carbon ratio mole per mole mol/mol 1 C # number... error between a quantity and its reference e brake-specific emission or fuel consumption gram per... standard deviation S Sutherland constant kelvin K K SEE standard estimate of error T absolute temperature...

Standard errors in forest area

Treesearch

Joseph McCollum

2002-01-01

I trace the development of standard error equations for forest area, beginning with the theory behind double sampling and the variance of a product. The discussion shifts to the particular problem of forest area - at which time the theory becomes relevant. There are subtle difficulties in figuring out which variance of a product equation should be used. The equations...

Analyzing Multilevel Data: An Empirical Comparison of Parameter Estimates of Hierarchical Linear Modeling and Ordinary Least Squares Regression

ERIC Educational Resources Information Center

Rocconi, Louis M.

2011-01-01

Hierarchical linear models (HLM) solve the problems associated with the unit of analysis problem such as misestimated standard errors, heterogeneity of regression and aggregation bias by modeling all levels of interest simultaneously. Hierarchical linear modeling resolves the problem of misestimated standard errors by incorporating a unique random…

A Sandwich-Type Standard Error Estimator of SEM Models with Multivariate Time Series

ERIC Educational Resources Information Center

Zhang, Guangjian; Chow, Sy-Miin; Ong, Anthony D.

2011-01-01

Structural equation models are increasingly used as a modeling tool for multivariate time series data in the social and behavioral sciences. Standard error estimators of SEM models, originally developed for independent data, require modifications to accommodate the fact that time series data are inherently dependent. In this article, we extend a…

Patient Safety: Moving the Bar in Prison Health Care Standards

PubMed Central

Greifinger, Robert B.; Mellow, Jeff

2010-01-01

Improvements in community health care quality through error reduction have been slow to transfer to correctional settings. We convened a panel of correctional experts, which recommended 60 patient safety standards focusing on such issues as creating safety cultures at organizational, supervisory, and staff levels through changes to policy and training and by ensuring staff competency, reducing medication errors, encouraging the seamless transfer of information between and within practice settings, and developing mechanisms to detect errors or near misses and to shift the emphasis from blaming staff to fixing systems. To our knowledge, this is the first published set of standards focusing on patient safety in prisons, adapted from the emerging literature on quality improvement in the community. PMID:20864714

Kappa statistic for the clustered dichotomous responses from physicians and patients

PubMed Central

Kang, Chaeryon; Qaqish, Bahjat; Monaco, Jane; Sheridan, Stacey L.; Cai, Jianwen

2013-01-01

The bootstrap method for estimating the standard error of the kappa statistic in the presence of clustered data is evaluated. Such data arise, for example, in assessing agreement between physicians and their patients regarding their understanding of the physician-patient interaction and discussions. We propose a computationally efficient procedure for generating correlated dichotomous responses for physicians and assigned patients for simulation studies. The simulation result demonstrates that the proposed bootstrap method produces better estimate of the standard error and better coverage performance compared to the asymptotic standard error estimate that ignores dependence among patients within physicians with at least a moderately large number of clusters. An example of an application to a coronary heart disease prevention study is presented. PMID:23533082

Using the Sampling Margin of Error to Assess the Interpretative Validity of Student Evaluations of Teaching

ERIC Educational Resources Information Center

James, David E.; Schraw, Gregory; Kuch, Fred

2015-01-01

We present an equation, derived from standard statistical theory, that can be used to estimate sampling margin of error for student evaluations of teaching (SETs). We use the equation to examine the effect of sample size, response rates and sample variability on the estimated sampling margin of error, and present results in four tables that allow…

Comparison of Predictive Modeling Methods of Aircraft Landing Speed

NASA Technical Reports Server (NTRS)

Diallo, Ousmane H.

2012-01-01

Expected increases in air traffic demand have stimulated the development of air traffic control tools intended to assist the air traffic controller in accurately and precisely spacing aircraft landing at congested airports. Such tools will require an accurate landing-speed prediction to increase throughput while decreasing necessary controller interventions for avoiding separation violations. There are many practical challenges to developing an accurate landing-speed model that has acceptable prediction errors. This paper discusses the development of a near-term implementation, using readily available information, to estimate/model final approach speed from the top of the descent phase of flight to the landing runway. As a first approach, all variables found to contribute directly to the landing-speed prediction model are used to build a multi-regression technique of the response surface equation (RSE). Data obtained from operations of a major airlines for a passenger transport aircraft type to the Dallas/Fort Worth International Airport are used to predict the landing speed. The approach was promising because it decreased the standard deviation of the landing-speed error prediction by at least 18% from the standard deviation of the baseline error, depending on the gust condition at the airport. However, when the number of variables is reduced to the most likely obtainable at other major airports, the RSE model shows little improvement over the existing methods. Consequently, a neural network that relies on a nonlinear regression technique is utilized as an alternative modeling approach. For the reduced number of variables cases, the standard deviation of the neural network models errors represent over 5% reduction compared to the RSE model errors, and at least 10% reduction over the baseline predicted landing-speed error standard deviation. Overall, the constructed models predict the landing-speed more accurately and precisely than the current state-of-the-art.

Flight calibration of compensated and uncompensated pitot-static airspeed probes and application of the probes to supersonic cruise vehicles

NASA Technical Reports Server (NTRS)

Webb, L. D.; Washington, H. P.

1972-01-01

Static pressure position error calibrations for a compensated and an uncompensated XB-70 nose boom pitot static probe were obtained in flight. The methods (Pacer, acceleration-deceleration, and total temperature) used to obtain the position errors over a Mach number range from 0.5 to 3.0 and an altitude range from 25,000 feet to 70,000 feet are discussed. The error calibrations are compared with the position error determined from wind tunnel tests, theoretical analysis, and a standard NACA pitot static probe. Factors which influence position errors, such as angle of attack, Reynolds number, probe tip geometry, static orifice location, and probe shape, are discussed. Also included are examples showing how the uncertainties caused by position errors can affect the inlet controls and vertical altitude separation of a supersonic transport.

A GPS Phase-Locked Loop Performance Metric Based on the Phase Discriminator Output

PubMed Central

Stevanovic, Stefan; Pervan, Boris

2018-01-01

We propose a novel GPS phase-lock loop (PLL) performance metric based on the standard deviation of tracking error (defined as the discriminator’s estimate of the true phase error), and explain its advantages over the popular phase jitter metric using theory, numerical simulation, and experimental results. We derive an augmented GPS phase-lock loop (PLL) linear model, which includes the effect of coherent averaging, to be used in conjunction with this proposed metric. The augmented linear model allows more accurate calculation of tracking error standard deviation in the presence of additive white Gaussian noise (AWGN) as compared to traditional linear models. The standard deviation of tracking error, with a threshold corresponding to half of the arctangent discriminator pull-in region, is shown to be a more reliable/robust measure of PLL performance under interference conditions than the phase jitter metric. In addition, the augmented linear model is shown to be valid up until this threshold, which facilitates efficient performance prediction, so that time-consuming direct simulations and costly experimental testing can be reserved for PLL designs that are much more likely to be successful. The effect of varying receiver reference oscillator quality on the tracking error metric is also considered. PMID:29351250

Selective Weighted Least Squares Method for Fourier Transform Infrared Quantitative Analysis.

PubMed

Wang, Xin; Li, Yan; Wei, Haoyun; Chen, Xia

2017-06-01

Classical least squares (CLS) regression is a popular multivariate statistical method used frequently for quantitative analysis using Fourier transform infrared (FT-IR) spectrometry. Classical least squares provides the best unbiased estimator for uncorrelated residual errors with zero mean and equal variance. However, the noise in FT-IR spectra, which accounts for a large portion of the residual errors, is heteroscedastic. Thus, if this noise with zero mean dominates in the residual errors, the weighted least squares (WLS) regression method described in this paper is a better estimator than CLS. However, if bias errors, such as the residual baseline error, are significant, WLS may perform worse than CLS. In this paper, we compare the effect of noise and bias error in using CLS and WLS in quantitative analysis. Results indicated that for wavenumbers with low absorbance, the bias error significantly affected the error, such that the performance of CLS is better than that of WLS. However, for wavenumbers with high absorbance, the noise significantly affected the error, and WLS proves to be better than CLS. Thus, we propose a selective weighted least squares (SWLS) regression that processes data with different wavenumbers using either CLS or WLS based on a selection criterion, i.e., lower or higher than an absorbance threshold. The effects of various factors on the optimal threshold value (OTV) for SWLS have been studied through numerical simulations. These studies reported that: (1) the concentration and the analyte type had minimal effect on OTV; and (2) the major factor that influences OTV is the ratio between the bias error and the standard deviation of the noise. The last part of this paper is dedicated to quantitative analysis of methane gas spectra, and methane/toluene mixtures gas spectra as measured using FT-IR spectrometry and CLS, WLS, and SWLS. The standard error of prediction (SEP), bias of prediction (bias), and the residual sum of squares of the errors (RSS) from the three quantitative analyses were compared. In methane gas analysis, SWLS yielded the lowest SEP and RSS among the three methods. In methane/toluene mixture gas analysis, a modification of the SWLS has been presented to tackle the bias error from other components. The SWLS without modification presents the lowest SEP in all cases but not bias and RSS. The modification of SWLS reduced the bias, which showed a lower RSS than CLS, especially for small components.

Errors in preparation and administration of parenteral drugs in neonatology: evaluation and corrective actions.

PubMed

Hasni, Nesrine; Ben Hamida, Emira; Ben Jeddou, Khouloud; Ben Hamida, Sarra; Ayadi, Imene; Ouahchi, Zeineb; Marrakchi, Zahra

2016-12-01

The medication iatrogenic risk is quite unevaluated in neonatology Objective: Assessment of errors that occurred during the preparation and administration of injectable medicines in a neonatal unit in order to implement corrective actions to reduce the occurrence of these errors. A prospective, observational study was performed in a neonatal unit over a period of one month. The practice of preparing and administering injectable medications were identified through a standardized data collection form. These practices were compared with summaries of the characteristics of each product (RCP) and the bibliography. One hundred preparations were observed of 13 different drugs. 85 errors during preparations and administration steps were detected. These errors were divided into preparation errors in 59% of cases such as changing the dilution protocol (32%), the use of bad solvent (11%) and administration errors in 41% of cases as errors timing of administration (18%) or omission of administration (9%). This study showed a high rate of errors during stages of preparation and administration of injectable drugs. In order to optimize the care of newborns and reduce the risk of medication errors, corrective actions have been implemented through the establishment of a quality assurance system which consisted of the development of injectable drugs preparation procedures, the introduction of a labeling system and staff training.

Composite Gauss-Legendre Quadrature with Error Control

ERIC Educational Resources Information Center

Prentice, J. S. C.

2011-01-01

We describe composite Gauss-Legendre quadrature for determining definite integrals, including a means of controlling the approximation error. We compare the form and performance of the algorithm with standard Newton-Cotes quadrature. (Contains 1 table.)

Lost in Translation: the Case for Integrated Testing

NASA Technical Reports Server (NTRS)

Young, Aaron

2017-01-01

The building of a spacecraft is complex and often involves multiple suppliers and companies that have their own designs and processes. Standards have been developed across the industries to reduce the chances for critical flight errors at the system level, but the spacecraft is still vulnerable to the introduction of critical errors during integration of these systems. Critical errors can occur at any time during the process and in many cases, human reliability analysis (HRA) identifies human error as a risk driver. Most programs have a test plan in place that is intended to catch these errors, but it is not uncommon for schedule and cost stress to result in less testing than initially planned. Therefore, integrated testing, or "testing as you fly," is essential as a final check on the design and assembly to catch any errors prior to the mission. This presentation will outline the unique benefits of integrated testing by catching critical flight errors that can otherwise go undetected, discuss HRA methods that are used to identify opportunities for human error, lessons learned and challenges over ownership of testing will be discussed.

Development and implementation of a human accuracy program in patient foodservice.

PubMed

Eden, S H; Wood, S M; Ptak, K M

1987-04-01

For many years, industry has utilized the concept of human error rates to monitor and minimize human errors in the production process. A consistent quality-controlled product increases consumer satisfaction and repeat purchase of product. Administrative dietitians have applied the concepts of using human error rates (the number of errors divided by the number of opportunities for error) at four hospitals, with a total bed capacity of 788, within a tertiary-care medical center. Human error rate was used to monitor and evaluate trayline employee performance and to evaluate layout and tasks of trayline stations, in addition to evaluating employees in patient service areas. Long-term employees initially opposed the error rate system with some hostility and resentment, while newer employees accepted the system. All employees now believe that the constant feedback given by supervisors enhances their self-esteem and productivity. Employee error rates are monitored daily and are used to counsel employees when necessary; they are also utilized during annual performance evaluation. Average daily error rates for a facility staffed by new employees decreased from 7% to an acceptable 3%. In a facility staffed by long-term employees, the error rate increased, reflecting improper error documentation. Patient satisfaction surveys reveal satisfaction, for tray accuracy increased from 88% to 92% in the facility staffed by long-term employees and has remained above the 90% standard in the facility staffed by new employees.

Degrees of Freedom for Allan Deviation Estimates of Multiple Clocks

DTIC Science & Technology

2016-04-01

Allan deviation . Allan deviation will be represented by σ and standard deviation will be represented by δ. In practice, when the Allan deviation of a...the Allan deviation of standard noise types. Once the number of degrees of freedom is known, an approximate confidence interval can be assigned by...measurement errors from paired difference data. We extend this approach by using the Allan deviation to estimate the error in a frequency standard

Evaluating the Effective Factors for Reporting Medical Errors among Midwives Working at Teaching Hospitals Affiliated to Isfahan University of Medical Sciences.

PubMed

Khorasani, Fahimeh; Beigi, Marjan

2017-01-01

Recently, evaluation and accreditation system of hospitals has had a special emphasis on reporting malpractices and sharing errors or lessons learnt from errors, but still due to lack of promotion of systematic approach for solving problems from the same system, this issue has remained unattended. This study was conducted to determine the effective factors for reporting medical errors among midwives. This project was a descriptive cross-sectional observational study. Data gathering tools were a standard checklist and two researcher-made questionnaires. Sampling for this study was conducted from all the midwives who worked at teaching hospitals affiliated to Isfahan University of Medical Sciences through census method (convenient) and lasted for 3 months. Data were analyzed using descriptive and inferential statistics through SPSS 16. Results showed that 79.1% of the staff reported errors and the highest rate of errors was in the process of patients' tests. In this study, the mean score of midwives' knowledge about the errors was 79.1 and the mean score of their attitude toward reporting errors was 70.4. There was a direct relation between the score of errors' knowledge and attitude in the midwifery staff and reporting errors. Based on the results of this study about the appropriate knowledge and attitude of midwifery staff regarding errors and action toward reporting them, it is recommended to strengthen the system when it comes to errors and hospitals risks.

Error Analyses of the North Alabama Lightning Mapping Array (LMA)

NASA Technical Reports Server (NTRS)

Koshak, W. J.; Solokiewicz, R. J.; Blakeslee, R. J.; Goodman, S. J.; Christian, H. J.; Hall, J. M.; Bailey, J. C.; Krider, E. P.; Bateman, M. G.; Boccippio, D. J.

2003-01-01

Two approaches are used to characterize how accurately the North Alabama Lightning Mapping Array (LMA) is able to locate lightning VHF sources in space and in time. The first method uses a Monte Carlo computer simulation to estimate source retrieval errors. The simulation applies a VHF source retrieval algorithm that was recently developed at the NASA-MSFC and that is similar, but not identical to, the standard New Mexico Tech retrieval algorithm. The second method uses a purely theoretical technique (i.e., chi-squared Curvature Matrix theory) to estimate retrieval errors. Both methods assume that the LMA system has an overall rms timing error of 50ns, but all other possible errors (e.g., multiple sources per retrieval attempt) are neglected. The detailed spatial distributions of retrieval errors are provided. Given that the two methods are completely independent of one another, it is shown that they provide remarkably similar results, except that the chi-squared theory produces larger altitude error estimates than the (more realistic) Monte Carlo simulation.

Risk Factors for Increased Severity of Paediatric Medication Administration Errors

PubMed Central

Sears, Kim; Goodman, William M.

2012-01-01

Patients' risks from medication errors are widely acknowledged. Yet not all errors, if they occur, have the same risks for severe consequences. Facing resource constraints, policy makers could prioritize factors having the greatest severe–outcome risks. This study assists such prioritization by identifying work-related risk factors most clearly associated with more severe consequences. Data from three Canadian paediatric centres were collected, without identifiers, on actual or potential errors that occurred. Three hundred seventy-two errors were reported, with outcome severities ranging from time delays up to fatalities. Four factors correlated significantly with increased risk for more severe outcomes: insufficient training; overtime; precepting a student; and off-service patient. Factors' impacts on severity also vary with error class: for wrong-time errors, the factors precepting a student or working overtime significantly increase severe-outcomes risk. For other types, caring for an off-service patient has greatest severity risk. To expand such research, better standardization is needed for categorizing outcome severities. PMID:23968607

Water quality management using statistical analysis and time-series prediction model

NASA Astrophysics Data System (ADS)

Parmar, Kulwinder Singh; Bhardwaj, Rashmi

2014-12-01

This paper deals with water quality management using statistical analysis and time-series prediction model. The monthly variation of water quality standards has been used to compare statistical mean, median, mode, standard deviation, kurtosis, skewness, coefficient of variation at Yamuna River. Model validated using R-squared, root mean square error, mean absolute percentage error, maximum absolute percentage error, mean absolute error, maximum absolute error, normalized Bayesian information criterion, Ljung-Box analysis, predicted value and confidence limits. Using auto regressive integrated moving average model, future water quality parameters values have been estimated. It is observed that predictive model is useful at 95 % confidence limits and curve is platykurtic for potential of hydrogen (pH), free ammonia, total Kjeldahl nitrogen, dissolved oxygen, water temperature (WT); leptokurtic for chemical oxygen demand, biochemical oxygen demand. Also, it is observed that predicted series is close to the original series which provides a perfect fit. All parameters except pH and WT cross the prescribed limits of the World Health Organization /United States Environmental Protection Agency, and thus water is not fit for drinking, agriculture and industrial use.

A Swiss cheese error detection method for real-time EPID-based quality assurance and error prevention.

PubMed

Passarge, Michelle; Fix, Michael K; Manser, Peter; Stampanoni, Marco F M; Siebers, Jeffrey V

2017-04-01

To develop a robust and efficient process that detects relevant dose errors (dose errors of ≥5%) in external beam radiation therapy and directly indicates the origin of the error. The process is illustrated in the context of electronic portal imaging device (EPID)-based angle-resolved volumetric-modulated arc therapy (VMAT) quality assurance (QA), particularly as would be implemented in a real-time monitoring program. A Swiss cheese error detection (SCED) method was created as a paradigm for a cine EPID-based during-treatment QA. For VMAT, the method compares a treatment plan-based reference set of EPID images with images acquired over each 2° gantry angle interval. The process utilizes a sequence of independent consecutively executed error detection tests: an aperture check that verifies in-field radiation delivery and ensures no out-of-field radiation; output normalization checks at two different stages; global image alignment check to examine if rotation, scaling, and translation are within tolerances; pixel intensity check containing the standard gamma evaluation (3%, 3 mm) and pixel intensity deviation checks including and excluding high dose gradient regions. Tolerances for each check were determined. To test the SCED method, 12 different types of errors were selected to modify the original plan. A series of angle-resolved predicted EPID images were artificially generated for each test case, resulting in a sequence of precalculated frames for each modified treatment plan. The SCED method was applied multiple times for each test case to assess the ability to detect introduced plan variations. To compare the performance of the SCED process with that of a standard gamma analysis, both error detection methods were applied to the generated test cases with realistic noise variations. Averaged over ten test runs, 95.1% of all plan variations that resulted in relevant patient dose errors were detected within 2° and 100% within 14° (<4% of patient dose delivery). Including cases that led to slightly modified but clinically equivalent plans, 89.1% were detected by the SCED method within 2°. Based on the type of check that detected the error, determination of error sources was achieved. With noise ranging from no random noise to four times the established noise value, the averaged relevant dose error detection rate of the SCED method was between 94.0% and 95.8% and that of gamma between 82.8% and 89.8%. An EPID-frame-based error detection process for VMAT deliveries was successfully designed and tested via simulations. The SCED method was inspected for robustness with realistic noise variations, demonstrating that it has the potential to detect a large majority of relevant dose errors. Compared to a typical (3%, 3 mm) gamma analysis, the SCED method produced a higher detection rate for all introduced dose errors, identified errors in an earlier stage, displayed a higher robustness to noise variations, and indicated the error source. © 2017 American Association of Physicists in Medicine.

Intermittent nocturnal hypoxia and metabolic risk in obese adolescents with obstructive sleep apnea.

PubMed

Narang, Indra; McCrindle, Brian W; Manlhiot, Cedric; Lu, Zihang; Al-Saleh, Suhail; Birken, Catherine S; Hamilton, Jill

2018-01-22

There is conflicting data regarding the independent associations of obstructive sleep apnea (OSA) with metabolic risk in obese youth. Previous studies have not consistently addressed central adiposity, specifically elevated waist to height ratio (WHtR), which is associated with metabolic risk independent of body mass index. The objective of this study was to determine the independent effects of the obstructive apnea-hypopnea index (OAHI) and associated indices of nocturnal hypoxia on metabolic function in obese youth after adjusting for WHtR. Subjects had standardized anthropometric measurements. Fasting blood included insulin, glucose, glycated hemoglobin, alanine transferase, and aspartate transaminase. Insulin resistance was quantified with the homeostatic model assessment. Overnight polysomnography determined the OAHI and nocturnal oxygenation indices. Of the 75 recruited subjects, 23% were diagnosed with OSA. Adjusting for age, gender, and WHtR in multivariable linear regression models, a higher oxygen desaturation index was associated with a higher fasting insulin (coefficient [standard error] = 48.076 [11.255], p < 0.001), higher glycated hemoglobin (coefficient [standard error] = 0.097 [0.041], p = 0.02), higher insulin resistance (coefficient [standard error] = 1.516 [0.364], p < 0.001), elevated alanine transferase (coefficient [standard error] = 11.631 [2.770], p < 0.001), and aspartate transaminase (coefficient [standard error] = 4.880 [1.444], p = 0.001). However, there were no significant associations between OAHI, glucose metabolism, and liver enzymes. Intermittent nocturnal hypoxia rather than the OAHI was associated with metabolic risk in obese youth after adjusting for WHtR. Measures of abdominal adiposity such as WHtR should be considered in future studies that evaluate the impact of OSA on metabolic health.

Error or "act of God"? A study of patients' and operating room team members' perceptions of error definition, reporting, and disclosure.

PubMed

Espin, Sherry; Levinson, Wendy; Regehr, Glenn; Baker, G Ross; Lingard, Lorelei

2006-01-01

Calls abound for a culture change in health care to improve patient safety. However, effective change cannot proceed without a clear understanding of perceptions and beliefs about error. In this study, we describe and compare operative team members' and patients' perceptions of error, reporting of error, and disclosure of error. Thirty-nine interviews of team members (9 surgeons, 9 nurses, 10 anesthesiologists) and patients (11) were conducted at 2 teaching hospitals using 4 scenarios as prompts. Transcribed responses to open questions were analyzed by 2 researchers for recurrent themes using the grounded-theory method. Yes/no answers were compared across groups using chi-square analyses. Team members and patients agreed on what constitutes an error. Deviation from standards and negative outcome were emphasized as definitive features. Patients and nurse professionals differed significantly in their perception of whether errors should be reported. Nurses were willing to report only events within their disciplinary scope of practice. Although most patients strongly advocated full disclosure of errors (what happened and how), team members preferred to disclose only what happened. When patients did support partial disclosure, their rationales varied from that of team members. Both operative teams and patients define error in terms of breaking the rules and the concept of "no harm no foul." These concepts pose challenges for treating errors as system failures. A strong culture of individualism pervades nurses' perception of error reporting, suggesting that interventions are needed to foster collective responsibility and a constructive approach to error identification.

Evaluation of quality indicators in a laboratory supporting tertiary cancer care facilities in India.

PubMed

Kumar, Savitha Anil; Jayanna, Prashanth; Prabhudesai, Shilpa; Kumar, Ajai

2014-01-01

To collect and tabulate errors and nonconformities in the preanalytical, analytical, and postanalytical process phases in a diagnostic clinical laboratory that supports a super-specialty cancer center in India, and identify areas of potential improvement in patient services. We collected data from our laboratory during a period of 24 months. Departments in the study included clinical biochemistry, hematology, clinical pathology, microbiology and serology, surgical pathology, and molecular pathology. We had initiated quality assessment based on international standards in our laboratory in 2010, with the aim of obtaining accreditation by national and international governing bodies. We followed the guidelines specified by International Organization for Standardization (ISO) 15189:2007 to identify noncompliant elements of our processes. Among a total of 144,030 specimens that our referral laboratory received during the 2-year period of our study, we uncovered an overall error rate for all 3 process phases of 1.23%; all of our error rates closely approximated the results from our peer institutions. Errors were most common in the preanalytical phase in both years of study; preanalytical- and postanalytical-phase errors constituted more than 90% of all errors. Further improvements are warranted in laboratory services and are contingent on adequate training and interdepartmental communication and cooperation. Copyright© by the American Society for Clinical Pathology (ASCP).

Evaluation of HACCP Plans of Food Industries: Case Study Conducted by the Servizio di Igiene degli Alimenti e della Nutrizione (Food and Nutrition Health Service) of the Local Health Authority of Foggia, Italy

PubMed Central

Panunzio, Michele F.; Antoniciello, Antonietta; Pisano, Alessandra; Rosa, Giovanna

2007-01-01

With respect to food safety, many works have studied the effectiveness of self-monitoring plans of food companies, designed using the Hazard Analysis and Critical Control Point (HACCP) method. On the other hand, in-depth research has not been made concerning the adherence of the plans to HACCP standards. During our research, we evaluated 116 self-monitoring plans adopted by food companies located in the territory of the Local Health Authority (LHA) of Foggia, Italy. The general errors (terminology, philosophy and redundancy) and the specific errors (transversal plan, critical limits, hazard specificity, and lack of procedures) were standardized. Concerning the general errors, terminological errors pertain to half the plans examined, 47% include superfluous elements and 60% have repetitive subjects. With regards to the specific errors, 77% of the plans examined contained specific errors. The evaluation has pointed out the lack of comprehension of the HACCP system by the food companies and has allowed the Servizio di Igiene degli Alimenti e della Nutrizione (Food and Nutrition Health Service), in its capacity as a control body, to intervene with the companies in order to improve designing HACCP plans. PMID:17911662

Estimating Bias Error Distributions

NASA Technical Reports Server (NTRS)

Liu, Tian-Shu; Finley, Tom D.

2001-01-01

This paper formulates the general methodology for estimating the bias error distribution of a device in a measuring domain from less accurate measurements when a minimal number of standard values (typically two values) are available. A new perspective is that the bias error distribution can be found as a solution of an intrinsic functional equation in a domain. Based on this theory, the scaling- and translation-based methods for determining the bias error distribution arc developed. These methods are virtually applicable to any device as long as the bias error distribution of the device can be sufficiently described by a power series (a polynomial) or a Fourier series in a domain. These methods have been validated through computational simulations and laboratory calibration experiments for a number of different devices.

Sources of variability and systematic error in mouse timing behavior.

PubMed

Gallistel, C R; King, Adam; McDonald, Robert

2004-01-01

In the peak procedure, starts and stops in responding bracket the target time at which food is expected. The variability in start and stop times is proportional to the target time (scalar variability), as is the systematic error in the mean center (scalar error). The authors investigated the source of the error and the variability, using head poking in the mouse, with target intervals of 5 s, 15 s, and 45 s, in the standard procedure, and in a variant with 3 different target intervals at 3 different locations in a single trial. The authors conclude that the systematic error is due to the asymmetric location of start and stop decision criteria, and the scalar variability derives primarily from sources other than memory.

Measuring quality in anatomic pathology.

PubMed

Raab, Stephen S; Grzybicki, Dana Marie

2008-06-01

This article focuses mainly on diagnostic accuracy in measuring quality in anatomic pathology, noting that measuring any quality metric is complex and demanding. The authors discuss standardization and its variability within and across areas of care delivery and efforts involving defining and measuring error to achieve pathology quality and patient safety. They propose that data linking error to patient outcome are critical for developing quality improvement initiatives targeting errors that cause patient harm in addition to using methods of root cause analysis, beyond those traditionally used in cytologic-histologic correlation, to assist in the development of error reduction and quality improvement plans.

The Cut-Score Operating Function: A New Tool to Aid in Standard Setting

ERIC Educational Resources Information Center

Grabovsky, Irina; Wainer, Howard

2017-01-01

In this essay, we describe the construction and use of the Cut-Score Operating Function in aiding standard setting decisions. The Cut-Score Operating Function shows the relation between the cut-score chosen and the consequent error rate. It allows error rates to be defined by multiple loss functions and will show the behavior of each loss…

A Hands-On Exercise Improves Understanding of the Standard Error of the Mean

ERIC Educational Resources Information Center

Ryan, Robert S.

2006-01-01

One of the most difficult concepts for statistics students is the standard error of the mean. To improve understanding of this concept, 1 group of students used a hands-on procedure to sample from small populations representing either a true or false null hypothesis. The distribution of 120 sample means (n = 3) from each population had standard…

Estimation of Standard Error of Regression Effects in Latent Regression Models Using Binder's Linearization. Research Report. ETS RR-07-09

ERIC Educational Resources Information Center

Li, Deping; Oranje, Andreas

2007-01-01

Two versions of a general method for approximating standard error of regression effect estimates within an IRT-based latent regression model are compared. The general method is based on Binder's (1983) approach, accounting for complex samples and finite populations by Taylor series linearization. In contrast, the current National Assessment of…

A partial least squares based spectrum normalization method for uncertainty reduction for laser-induced breakdown spectroscopy measurements

NASA Astrophysics Data System (ADS)

Li, Xiongwei; Wang, Zhe; Lui, Siu-Lung; Fu, Yangting; Li, Zheng; Liu, Jianming; Ni, Weidou

2013-10-01

A bottleneck of the wide commercial application of laser-induced breakdown spectroscopy (LIBS) technology is its relatively high measurement uncertainty. A partial least squares (PLS) based normalization method was proposed to improve pulse-to-pulse measurement precision for LIBS based on our previous spectrum standardization method. The proposed model utilized multi-line spectral information of the measured element and characterized the signal fluctuations due to the variation of plasma characteristic parameters (plasma temperature, electron number density, and total number density) for signal uncertainty reduction. The model was validated by the application of copper concentration prediction in 29 brass alloy samples. The results demonstrated an improvement on both measurement precision and accuracy over the generally applied normalization as well as our previously proposed simplified spectrum standardization method. The average relative standard deviation (RSD), average of the standard error (error bar), the coefficient of determination (R2), the root-mean-square error of prediction (RMSEP), and average value of the maximum relative error (MRE) were 1.80%, 0.23%, 0.992, 1.30%, and 5.23%, respectively, while those for the generally applied spectral area normalization were 3.72%, 0.71%, 0.973, 1.98%, and 14.92%, respectively.

Cost-effectiveness of the streamflow-gaging program in Wyoming

USGS Publications Warehouse

Druse, S.A.; Wahl, K.L.

1988-01-01

This report documents the results of a cost-effectiveness study of the streamflow-gaging program in Wyoming. Regression analysis or hydrologic flow-routing techniques were considered for 24 combinations of stations from a 139-station network operated in 1984 to investigate suitability of techniques for simulating streamflow records. Only one station was determined to have sufficient accuracy in the regression analysis to consider discontinuance of the gage. The evaluation of the gaging-station network, which included the use of associated uncertainty in streamflow records, is limited to the nonwinter operation of the 47 stations operated by the Riverton Field Office of the U.S. Geological Survey. The current (1987) travel routes and measurement frequencies require a budget of $264,000 and result in an average standard error in streamflow records of 13.2%. Changes in routes and station visits using the same budget, could optimally reduce the standard error by 1.6%. Budgets evaluated ranged from $235,000 to $400,000. A $235,000 budget increased the optimal average standard error/station from 11.6 to 15.5%, and a $400,000 budget could reduce it to 6.6%. For all budgets considered, lost record accounts for about 40% of the average standard error. (USGS)

Error-Transparent Quantum Gates for Small Logical Qubit Architectures

NASA Astrophysics Data System (ADS)

Kapit, Eliot

2018-02-01

One of the largest obstacles to building a quantum computer is gate error, where the physical evolution of the state of a qubit or group of qubits during a gate operation does not match the intended unitary transformation. Gate error stems from a combination of control errors and random single qubit errors from interaction with the environment. While great strides have been made in mitigating control errors, intrinsic qubit error remains a serious problem that limits gate fidelity in modern qubit architectures. Simultaneously, recent developments of small error-corrected logical qubit devices promise significant increases in logical state lifetime, but translating those improvements into increases in gate fidelity is a complex challenge. In this Letter, we construct protocols for gates on and between small logical qubit devices which inherit the parent device's tolerance to single qubit errors which occur at any time before or during the gate. We consider two such devices, a passive implementation of the three-qubit bit flip code, and the author's own [E. Kapit, Phys. Rev. Lett. 116, 150501 (2016), 10.1103/PhysRevLett.116.150501] very small logical qubit (VSLQ) design, and propose error-tolerant gate sets for both. The effective logical gate error rate in these models displays superlinear error reduction with linear increases in single qubit lifetime, proving that passive error correction is capable of increasing gate fidelity. Using a standard phenomenological noise model for superconducting qubits, we demonstrate a realistic, universal one- and two-qubit gate set for the VSLQ, with error rates an order of magnitude lower than those for same-duration operations on single qubits or pairs of qubits. These developments further suggest that incorporating small logical qubits into a measurement based code could substantially improve code performance.

Modeling error distributions of growth curve models through Bayesian methods.

PubMed

Zhang, Zhiyong

2016-06-01

Growth curve models are widely used in social and behavioral sciences. However, typical growth curve models often assume that the errors are normally distributed although non-normal data may be even more common than normal data. In order to avoid possible statistical inference problems in blindly assuming normality, a general Bayesian framework is proposed to flexibly model normal and non-normal data through the explicit specification of the error distributions. A simulation study shows when the distribution of the error is correctly specified, one can avoid the loss in the efficiency of standard error estimates. A real example on the analysis of mathematical ability growth data from the Early Childhood Longitudinal Study, Kindergarten Class of 1998-99 is used to show the application of the proposed methods. Instructions and code on how to conduct growth curve analysis with both normal and non-normal error distributions using the the MCMC procedure of SAS are provided.

The Influence of Effortful Thought and Cognitive Proficiencies on the Conjunction Fallacy: Implications for Dual-Process Theories of Reasoning and Judgment.

PubMed

Scherer, Laura D; Yates, J Frank; Baker, S Glenn; Valentine, Kathrene D

2017-06-01

Human judgment often violates normative standards, and virtually no judgment error has received as much attention as the conjunction fallacy. Judgment errors have historically served as evidence for dual-process theories of reasoning, insofar as these errors are assumed to arise from reliance on a fast and intuitive mental process, and are corrected via effortful deliberative reasoning. In the present research, three experiments tested the notion that conjunction errors are reduced by effortful thought. Predictions based on three different dual-process theory perspectives were tested: lax monitoring, override failure, and the Tripartite Model. Results indicated that participants higher in numeracy were less likely to make conjunction errors, but this association only emerged when participants engaged in two-sided reasoning, as opposed to one-sided or no reasoning. Confidence was higher for incorrect as opposed to correct judgments, suggesting that participants were unaware of their errors.

Application of genetic algorithm in the evaluation of the profile error of archimedes helicoid surface

NASA Astrophysics Data System (ADS)

Zhu, Lianqing; Chen, Yunfang; Chen, Qingshan; Meng, Hao

2011-05-01

According to minimum zone condition, a method for evaluating the profile error of Archimedes helicoid surface based on Genetic Algorithm (GA) is proposed. The mathematic model of the surface is provided and the unknown parameters in the equation of surface are acquired through least square method. Principle of GA is explained. Then, the profile error of Archimedes Helicoid surface is obtained through GA optimization method. To validate the proposed method, the profile error of an Archimedes helicoid surface, Archimedes Cylindrical worm (ZA worm) surface, is evaluated. The results show that the proposed method is capable of correctly evaluating the profile error of Archimedes helicoid surface and satisfy the evaluation standard of the Minimum Zone Method. It can be applied to deal with the measured data of profile error of complex surface obtained by three coordinate measurement machines (CMM).

Backward-gazing method for measuring solar concentrators shape errors.

PubMed

Coquand, Mathieu; Henault, François; Caliot, Cyril

2017-03-01

This paper describes a backward-gazing method for measuring the optomechanical errors of solar concentrating surfaces. It makes use of four cameras placed near the solar receiver and simultaneously recording images of the sun reflected by the optical surfaces. Simple data processing then allows reconstructing the slope and shape errors of the surfaces. The originality of the method is enforced by the use of generalized quad-cell formulas and approximate mathematical relations between the slope errors of the mirrors and their reflected wavefront in the case of sun-tracking heliostats at high-incidence angles. Numerical simulations demonstrate that the measurement accuracy is compliant with standard requirements of solar concentrating optics in the presence of noise or calibration errors. The method is suited to fine characterization of the optical and mechanical errors of heliostats and their facets, or to provide better control for real-time sun tracking.

Checkpoint-based forward recovery using lookahead execution and rollback validation in parallel and distributed systems. Ph.D. Thesis, 1992

NASA Technical Reports Server (NTRS)

Long, Junsheng

1994-01-01

This thesis studies a forward recovery strategy using checkpointing and optimistic execution in parallel and distributed systems. The approach uses replicated tasks executing on different processors for forwared recovery and checkpoint comparison for error detection. To reduce overall redundancy, this approach employs a lower static redundancy in the common error-free situation to detect error than the standard N Module Redundancy scheme (NMR) does to mask off errors. For the rare occurrence of an error, this approach uses some extra redundancy for recovery. To reduce the run-time recovery overhead, look-ahead processes are used to advance computation speculatively and a rollback process is used to produce a diagnosis for correct look-ahead processes without rollback of the whole system. Both analytical and experimental evaluation have shown that this strategy can provide a nearly error-free execution time even under faults with a lower average redundancy than NMR.

Kappa statistic for clustered dichotomous responses from physicians and patients.

PubMed

Kang, Chaeryon; Qaqish, Bahjat; Monaco, Jane; Sheridan, Stacey L; Cai, Jianwen

2013-09-20

The bootstrap method for estimating the standard error of the kappa statistic in the presence of clustered data is evaluated. Such data arise, for example, in assessing agreement between physicians and their patients regarding their understanding of the physician-patient interaction and discussions. We propose a computationally efficient procedure for generating correlated dichotomous responses for physicians and assigned patients for simulation studies. The simulation result demonstrates that the proposed bootstrap method produces better estimate of the standard error and better coverage performance compared with the asymptotic standard error estimate that ignores dependence among patients within physicians with at least a moderately large number of clusters. We present an example of an application to a coronary heart disease prevention study. Copyright © 2013 John Wiley & Sons, Ltd.

Multicollinearity and Regression Analysis

NASA Astrophysics Data System (ADS)

Daoud, Jamal I.

2017-12-01

In regression analysis it is obvious to have a correlation between the response and predictor(s), but having correlation among predictors is something undesired. The number of predictors included in the regression model depends on many factors among which, historical data, experience, etc. At the end selection of most important predictors is something objective due to the researcher. Multicollinearity is a phenomena when two or more predictors are correlated, if this happens, the standard error of the coefficients will increase [8]. Increased standard errors means that the coefficients for some or all independent variables may be found to be significantly different from In other words, by overinflating the standard errors, multicollinearity makes some variables statistically insignificant when they should be significant. In this paper we focus on the multicollinearity, reasons and consequences on the reliability of the regression model.

Nature of nursing errors and their contributing factors in intensive care units.

PubMed

Eltaybani, Sameh; Mohamed, Nadia; Abdelwareth, Mona

2018-04-27

Errors tend to be multifactorial and so learning from nurses' experiences with them would be a powerful tool toward promoting patient safety. To identify the nature of nursing errors and their contributing factors in intensive care units (ICUs). A semi-structured interview with 112 critical care nurses to elicit the reports about their encountered errors followed by a content analysis. A total of 300 errors were reported. Most of them (94·3%) were classified in more than one error category, e.g. 'lack of intervention', 'lack of attentiveness' and 'documentation errors': these were the most frequently involved error categories. Approximately 40% of reported errors contributed to significant harm or death of the involved patients, with system-related factors being involved in 84·3% of them. More errors occur during the evening shift than the night and morning shifts (42·7% versus 28·7% and 16·7%, respectively). There is a statistically significant relation (p ≤ 0·001) between error disclosure to a nursing supervisor and its impact on the patient. Nurses are more likely to report their errors when they feel safe and when the reporting system is not burdensome, although an internationally standardized language to define and analyse nursing errors is needed. Improving the health care system, particularly the managerial and environmental aspects, might reduce nursing errors in ICUs in terms of their incidence and seriousness. Targeting error-liable times in the ICU, such as mid-evening and mid-night shifts, along with improved supervision and adequate staff reallocation, might tackle the incidence and seriousness of nursing errors. Development of individualized nursing interventions for patients with low health literacy and patients in isolation might create more meaningful dialogue for ICU health care safety. © 2018 British Association of Critical Care Nurses.

High-Accuracy Surface Figure Measurement of Silicon Mirrors at 80 K

NASA Technical Reports Server (NTRS)

Blake, Peter; Mink, Ronald G.; Chambers, John; Davila, Pamela; Robinson, F. David

2004-01-01

This report describes the equipment, experimental methods, and first results at a new facility for interferometric measurement of cryogenically-cooled spherical mirrors at the Goddard Space Flight Center Optics Branch. The procedure, using standard phase-shifting interferometry, has an standard combined uncertainty of 3.6 nm rms in its representation of the two-dimensional surface figure error at 80, and an uncertainty of plus or minus 1 nm in the rms statistic itself. The first mirror tested was a concave spherical silicon foam-core mirror, with a clear aperture of 120 mm. The optic surface was measured at room temperature using standard absolute techniques; and then the change in surface figure error from room temperature to 80 K was measured. The mirror was cooled within a cryostat. and its surface figure error measured through a fused-silica window. The facility and techniques will be used to measure the surface figure error at 20K of prototype lightweight silicon carbide and Cesic mirrors developed by Galileo Avionica (Italy) for the European Space Agency (ESA).

Bootstrap-based methods for estimating standard errors in Cox's regression analyses of clustered event times.

PubMed

Xiao, Yongling; Abrahamowicz, Michal

2010-03-30

We propose two bootstrap-based methods to correct the standard errors (SEs) from Cox's model for within-cluster correlation of right-censored event times. The cluster-bootstrap method resamples, with replacement, only the clusters, whereas the two-step bootstrap method resamples (i) the clusters, and (ii) individuals within each selected cluster, with replacement. In simulations, we evaluate both methods and compare them with the existing robust variance estimator and the shared gamma frailty model, which are available in statistical software packages. We simulate clustered event time data, with latent cluster-level random effects, which are ignored in the conventional Cox's model. For cluster-level covariates, both proposed bootstrap methods yield accurate SEs, and type I error rates, and acceptable coverage rates, regardless of the true random effects distribution, and avoid serious variance under-estimation by conventional Cox-based standard errors. However, the two-step bootstrap method over-estimates the variance for individual-level covariates. We also apply the proposed bootstrap methods to obtain confidence bands around flexible estimates of time-dependent effects in a real-life analysis of cluster event times.

Tracking Progress in Improving Diagnosis: A Framework for Defining Undesirable Diagnostic Events.

PubMed

Olson, Andrew P J; Graber, Mark L; Singh, Hardeep

2018-01-29

Diagnostic error is a prevalent, harmful, and costly phenomenon. Multiple national health care and governmental organizations have recently identified the need to improve diagnostic safety as a high priority. A major barrier, however, is the lack of standardized, reliable methods for measuring diagnostic safety. Given the absence of reliable and valid measures for diagnostic errors, we need methods to help establish some type of baseline diagnostic performance across health systems, as well as to enable researchers and health systems to determine the impact of interventions for improving the diagnostic process. Multiple approaches have been suggested but none widely adopted. We propose a new framework for identifying "undesirable diagnostic events" (UDEs) that health systems, professional organizations, and researchers could further define and develop to enable standardized measurement and reporting related to diagnostic safety. We propose an outline for UDEs that identifies both conditions prone to diagnostic error and the contexts of care in which these errors are likely to occur. Refinement and adoption of this framework across health systems can facilitate standardized measurement and reporting of diagnostic safety.

Translating Radiometric Requirements for Satellite Sensors to Match International Standards.

PubMed

Pearlman, Aaron; Datla, Raju; Kacker, Raghu; Cao, Changyong

2014-01-01

International scientific standards organizations created standards on evaluating uncertainty in the early 1990s. Although scientists from many fields use these standards, they are not consistently implemented in the remote sensing community, where traditional error analysis framework persists. For a satellite instrument under development, this can create confusion in showing whether requirements are met. We aim to create a methodology for translating requirements from the error analysis framework to the modern uncertainty approach using the product level requirements of the Advanced Baseline Imager (ABI) that will fly on the Geostationary Operational Environmental Satellite R-Series (GOES-R). In this paper we prescribe a method to combine several measurement performance requirements, written using a traditional error analysis framework, into a single specification using the propagation of uncertainties formula. By using this approach, scientists can communicate requirements in a consistent uncertainty framework leading to uniform interpretation throughout the development and operation of any satellite instrument.

Translating Radiometric Requirements for Satellite Sensors to Match International Standards

PubMed Central

Pearlman, Aaron; Datla, Raju; Kacker, Raghu; Cao, Changyong

2014-01-01

International scientific standards organizations created standards on evaluating uncertainty in the early 1990s. Although scientists from many fields use these standards, they are not consistently implemented in the remote sensing community, where traditional error analysis framework persists. For a satellite instrument under development, this can create confusion in showing whether requirements are met. We aim to create a methodology for translating requirements from the error analysis framework to the modern uncertainty approach using the product level requirements of the Advanced Baseline Imager (ABI) that will fly on the Geostationary Operational Environmental Satellite R-Series (GOES-R). In this paper we prescribe a method to combine several measurement performance requirements, written using a traditional error analysis framework, into a single specification using the propagation of uncertainties formula. By using this approach, scientists can communicate requirements in a consistent uncertainty framework leading to uniform interpretation throughout the development and operation of any satellite instrument. PMID:26601032

Error-Detecting Identification Codes for Algebra Students.

ERIC Educational Resources Information Center

Sutherland, David C.

1990-01-01

Discusses common error-detecting identification codes using linear algebra terminology to provide an interesting application of algebra. Presents examples from the International Standard Book Number, the Universal Product Code, bank identification numbers, and the ZIP code bar code. (YP)

Developing and Validating Path-Dependent Uncertainty Estimates for use with the Regional Seismic Travel Time (RSTT) Model

NASA Astrophysics Data System (ADS)

Begnaud, M. L.; Anderson, D. N.; Phillips, W. S.; Myers, S. C.; Ballard, S.

2016-12-01

The Regional Seismic Travel Time (RSTT) tomography model has been developed to improve travel time predictions for regional phases (Pn, Sn, Pg, Lg) in order to increase seismic location accuracy, especially for explosion monitoring. The RSTT model is specifically designed to exploit regional phases for location, especially when combined with teleseismic arrivals. The latest RSTT model (version 201404um) has been released (http://www.sandia.gov/rstt). Travel time uncertainty estimates for RSTT are determined using one-dimensional (1D), distance-dependent error models, that have the benefit of being very fast to use in standard location algorithms, but do not account for path-dependent variations in error, and structural inadequacy of the RSTTT model (e.g., model error). Although global in extent, the RSTT tomography model is only defined in areas where data exist. A simple 1D error model does not accurately model areas where RSTT has not been calibrated. We are developing and validating a new error model for RSTT phase arrivals by mathematically deriving this multivariate model directly from a unified model of RSTT embedded into a statistical random effects model that captures distance, path and model error effects. An initial method developed is a two-dimensional path-distributed method using residuals. The goals for any RSTT uncertainty method are for it to be both readily useful for the standard RSTT user as well as improve travel time uncertainty estimates for location. We have successfully tested using the new error model for Pn phases and will demonstrate the method and validation of the error model for Sn, Pg, and Lg phases.

Computerized Orders with Standardized Concentrations Decrease Dispensing Errors of Continuous Infusion Medications for Pediatrics

PubMed Central

Sowan, Azizeh K.; Vaidya, Vinay U.; Soeken, Karen L.; Hilmas, Elora

2010-01-01

OBJECTIVES The use of continuous infusion medications with individualized concentrations may increase the risk for errors in pediatric patients. The objective of this study was to evaluate the effect of computerized prescriber order entry (CPOE) for continuous infusions with standardized concentrations on frequency of pharmacy processing errors. In addition, time to process handwritten versus computerized infusion orders was evaluated and user satisfaction with CPOE as compared to handwritten orders was measured. METHODS Using a crossover design, 10 pharmacists in the pediatric satellite within a university teaching hospital were given test scenarios of handwritten and CPOE order sheets and asked to process infusion orders using the pharmacy system in order to generate infusion labels. Participants were given three groups of orders: five correct handwritten orders, four handwritten orders written with deliberate errors, and five correct CPOE orders. Label errors were analyzed and time to complete the task was recorded. RESULTS Using CPOE orders, participants required less processing time per infusion order (2 min, 5 sec ± 58 sec) compared with time per infusion order in the first handwritten order sheet group (3 min, 7 sec ± 1 min, 20 sec) and the second handwritten order sheet group (3 min, 26 sec ± 1 min, 8 sec), (p<0.01). CPOE eliminated all error types except wrong concentration. With CPOE, 4% of infusions processed contained errors, compared with 26% of the first group of handwritten orders and 45% of the second group of handwritten orders (p<0.03). Pharmacists were more satisfied with CPOE orders when compared with the handwritten method (p=0.0001). CONCLUSIONS CPOE orders saved pharmacists' time and greatly improved the safety of processing continuous infusions, although not all errors were eliminated. pharmacists were overwhelmingly satisfied with the CPOE orders PMID:22477811

Merging gauge and satellite rainfall with specification of associated uncertainty across Australia

NASA Astrophysics Data System (ADS)

Woldemeskel, Fitsum M.; Sivakumar, Bellie; Sharma, Ashish

2013-08-01

Accurate estimation of spatial rainfall is crucial for modelling hydrological systems and planning and management of water resources. While spatial rainfall can be estimated either using rain gauge-based measurements or using satellite-based measurements, such estimates are subject to uncertainties due to various sources of errors in either case, including interpolation and retrieval errors. The purpose of the present study is twofold: (1) to investigate the benefit of merging rain gauge measurements and satellite rainfall data for Australian conditions and (2) to produce a database of retrospective rainfall along with a new uncertainty metric for each grid location at any timestep. The analysis involves four steps: First, a comparison of rain gauge measurements and the Tropical Rainfall Measuring Mission (TRMM) 3B42 data at such rain gauge locations is carried out. Second, gridded monthly rain gauge rainfall is determined using thin plate smoothing splines (TPSS) and modified inverse distance weight (MIDW) method. Third, the gridded rain gauge rainfall is merged with the monthly accumulated TRMM 3B42 using a linearised weighting procedure, the weights at each grid being calculated based on the error variances of each dataset. Finally, cross validation (CV) errors at rain gauge locations and standard errors at gridded locations for each timestep are estimated. The CV error statistics indicate that merging of the two datasets improves the estimation of spatial rainfall, and more so where the rain gauge network is sparse. The provision of spatio-temporal standard errors with the retrospective dataset is particularly useful for subsequent modelling applications where input error knowledge can help reduce the uncertainty associated with modelling outcomes.

The effect of errors in the assignment of the transmission functions on the accuracy of the thermal sounding of the atmosphere

NASA Technical Reports Server (NTRS)

Timofeyev, Y. M.

1979-01-01

In order to test the error of calculation in assumed values of the transmission function for Soviet and American radiometers sounding the atmosphere thermally from orbiting satellites, the assumptions of the transmission calculation is varied with respect to atmospheric CO2 content, transmission frequency, and atmospheric absorption. The error arising from variations of the assumptions from the standard basic model is calculated.

Transperineal prostate biopsy under magnetic resonance image guidance: a needle placement accuracy study.

PubMed

Blumenfeld, Philip; Hata, Nobuhiko; DiMaio, Simon; Zou, Kelly; Haker, Steven; Fichtinger, Gabor; Tempany, Clare M C

2007-09-01

To quantify needle placement accuracy of magnetic resonance image (MRI)-guided core needle biopsy of the prostate. A total of 10 biopsies were performed with 18-gauge (G) core biopsy needle via a percutaneous transperineal approach. Needle placement error was assessed by comparing the coordinates of preplanned targets with the needle tip measured from the intraprocedural coherent gradient echo images. The source of these errors was subsequently investigated by measuring displacement caused by needle deflection and needle susceptibility artifact shift in controlled phantom studies. Needle placement error due to misalignment of the needle template guide was also evaluated. The mean and standard deviation (SD) of errors in targeted biopsies was 6.5 +/- 3.5 mm. Phantom experiments showed significant placement error due to needle deflection with a needle with an asymmetrically beveled tip (3.2-8.7 mm depending on tissue type) but significantly smaller error with a symmetrical bevel (0.6-1.1 mm). Needle susceptibility artifacts observed a shift of 1.6 +/- 0.4 mm from the true needle axis. Misalignment of the needle template guide contributed an error of 1.5 +/- 0.3 mm. Needle placement error was clinically significant in MRI-guided biopsy for diagnosis of prostate cancer. Needle placement error due to needle deflection was the most significant cause of error, especially for needles with an asymmetrical bevel. (c) 2007 Wiley-Liss, Inc.

Error monitoring issues for common channel signaling

NASA Astrophysics Data System (ADS)

Hou, Victor T.; Kant, Krishna; Ramaswami, V.; Wang, Jonathan L.

1994-04-01

Motivated by field data which showed a large number of link changeovers and incidences of link oscillations between in-service and out-of-service states in common channel signaling (CCS) networks, a number of analyses of the link error monitoring procedures in the SS7 protocol were performed by the authors. This paper summarizes the results obtained thus far and include the following: (1) results of an exact analysis of the performance of the error monitoring procedures under both random and bursty errors; (2) a demonstration that there exists a range of error rates within which the error monitoring procedures of SS7 may induce frequent changeovers and changebacks; (3) an analysis of the performance ofthe SS7 level-2 transmission protocol to determine the tolerable error rates within which the delay requirements can be met; (4) a demonstration that the tolerable error rate depends strongly on various link and traffic characteristics, thereby implying that a single set of error monitor parameters will not work well in all situations; (5) some recommendations on a customizable/adaptable scheme of error monitoring with a discussion on their implementability. These issues may be particularly relevant in the presence of anticipated increases in SS7 traffic due to widespread deployment of Advanced Intelligent Network (AIN) and Personal Communications Service (PCS) as well as for developing procedures for high-speed SS7 links currently under consideration by standards bodies.

Single molecule counting and assessment of random molecular tagging errors with transposable giga-scale error-correcting barcodes.

PubMed

Lau, Billy T; Ji, Hanlee P

2017-09-21

RNA-Seq measures gene expression by counting sequence reads belonging to unique cDNA fragments. Molecular barcodes commonly in the form of random nucleotides were recently introduced to improve gene expression measures by detecting amplification duplicates, but are susceptible to errors generated during PCR and sequencing. This results in false positive counts, leading to inaccurate transcriptome quantification especially at low input and single-cell RNA amounts where the total number of molecules present is minuscule. To address this issue, we demonstrated the systematic identification of molecular species using transposable error-correcting barcodes that are exponentially expanded to tens of billions of unique labels. We experimentally showed random-mer molecular barcodes suffer from substantial and persistent errors that are difficult to resolve. To assess our method's performance, we applied it to the analysis of known reference RNA standards. By including an inline random-mer molecular barcode, we systematically characterized the presence of sequence errors in random-mer molecular barcodes. We observed that such errors are extensive and become more dominant at low input amounts. We described the first study to use transposable molecular barcodes and its use for studying random-mer molecular barcode errors. Extensive errors found in random-mer molecular barcodes may warrant the use of error correcting barcodes for transcriptome analysis as input amounts decrease.

Evaluation of a Web-based Error Reporting Surveillance System in a Large Iranian Hospital.

PubMed

Askarian, Mehrdad; Ghoreishi, Mahboobeh; Akbari Haghighinejad, Hourvash; Palenik, Charles John; Ghodsi, Maryam

2017-08-01

Proper reporting of medical errors helps healthcare providers learn from adverse incidents and improve patient safety. A well-designed and functioning confidential reporting system is an essential component to this process. There are many error reporting methods; however, web-based systems are often preferred because they can provide; comprehensive and more easily analyzed information. This study addresses the use of a web-based error reporting system. This interventional study involved the application of an in-house designed "voluntary web-based medical error reporting system." The system has been used since July 2014 in Nemazee Hospital, Shiraz University of Medical Sciences. The rate and severity of errors reported during the year prior and a year after system launch were compared. The slope of the error report trend line was steep during the first 12 months (B = 105.727, P = 0.00). However, it slowed following launch of the web-based reporting system and was no longer statistically significant (B = 15.27, P = 0.81) by the end of the second year. Most recorded errors were no-harm laboratory types and were due to inattention. Usually, they were reported by nurses and other permanent employees. Most reported errors occurred during morning shifts. Using a standardized web-based error reporting system can be beneficial. This study reports on the performance of an in-house designed reporting system, which appeared to properly detect and analyze medical errors. The system also generated follow-up reports in a timely and accurate manner. Detection of near-miss errors could play a significant role in identifying areas of system defects.

Voxel-based statistical analysis of uncertainties associated with deformable image registration

NASA Astrophysics Data System (ADS)

Li, Shunshan; Glide-Hurst, Carri; Lu, Mei; Kim, Jinkoo; Wen, Ning; Adams, Jeffrey N.; Gordon, James; Chetty, Indrin J.; Zhong, Hualiang

2013-09-01

Deformable image registration (DIR) algorithms have inherent uncertainties in their displacement vector fields (DVFs).The purpose of this study is to develop an optimal metric to estimate DIR uncertainties. Six computational phantoms have been developed from the CT images of lung cancer patients using a finite element method (FEM). The FEM generated DVFs were used as a standard for registrations performed on each of these phantoms. A mechanics-based metric, unbalanced energy (UE), was developed to evaluate these registration DVFs. The potential correlation between UE and DIR errors was explored using multivariate analysis, and the results were validated by landmark approach and compared with two other error metrics: DVF inverse consistency (IC) and image intensity difference (ID). Landmark-based validation was performed using the POPI-model. The results show that the Pearson correlation coefficient between UE and DIR error is rUE-error = 0.50. This is higher than rIC-error = 0.29 for IC and DIR error and rID-error = 0.37 for ID and DIR error. The Pearson correlation coefficient between UE and the product of the DIR displacements and errors is rUE-error × DVF = 0.62 for the six patients and rUE-error × DVF = 0.73 for the POPI-model data. It has been demonstrated that UE has a strong correlation with DIR errors, and the UE metric outperforms the IC and ID metrics in estimating DIR uncertainties. The quantified UE metric can be a useful tool for adaptive treatment strategies, including probability-based adaptive treatment planning.

Types of diagnostic errors in neurological emergencies in the emergency department.

PubMed

Dubosh, Nicole M; Edlow, Jonathan A; Lefton, Micah; Pope, Jennifer V

2015-02-01

Neurological emergencies often pose diagnostic challenges for emergency physicians because these patients often present with atypical symptoms and standard imaging tests are imperfect. Misdiagnosis occurs due to a variety of errors. These can be classified as knowledge gaps, cognitive errors, and systems-based errors. The goal of this study was to describe these errors through review of quality assurance (QA) records. This was a retrospective pilot study of patients with neurological emergency diagnoses that were missed or delayed at one urban, tertiary academic emergency department. Cases meeting inclusion criteria were identified through review of QA records. Three emergency physicians independently reviewed each case and determined the type of error that led to the misdiagnosis. Proportions, confidence intervals, and a reliability coefficient were calculated. During the study period, 1168 cases were reviewed. Forty-two cases were found to include a neurological misdiagnosis and twenty-nine were determined to be the result of an error. The distribution of error types was as follows: knowledge gap 45.2% (95% CI 29.2, 62.2), cognitive error 29.0% (95% CI 15.9, 46.8), and systems-based error 25.8% (95% CI 13.5, 43.5). Cerebellar strokes were the most common type of stroke misdiagnosed, accounting for 27.3% of missed strokes. All three error types contributed to the misdiagnosis of neurological emergencies. Misdiagnosis of cerebellar lesions and erroneous radiology resident interpretations of neuroimaging were the most common mistakes. Understanding the types of errors may enable emergency physicians to develop possible solutions and avoid them in the future.

Recognizing and managing errors of cognitive underspecification.

PubMed

Duthie, Elizabeth A

2014-03-01

James Reason describes cognitive underspecification as incomplete communication that creates a knowledge gap. Errors occur when an information mismatch occurs in bridging that gap with a resulting lack of shared mental models during the communication process. There is a paucity of studies in health care examining this cognitive error and the role it plays in patient harm. The goal of the following case analyses is to facilitate accurate recognition, identify how it contributes to patient harm, and suggest appropriate management strategies. Reason's human error theory is applied in case analyses of errors of cognitive underspecification. Sidney Dekker's theory of human incident investigation is applied to event investigation to facilitate identification of this little recognized error. Contributory factors leading to errors of cognitive underspecification include workload demands, interruptions, inexperienced practitioners, and lack of a shared mental model. Detecting errors of cognitive underspecification relies on blame-free listening and timely incident investigation. Strategies for interception include two-way interactive communication, standardization of communication processes, and technological support to ensure timely access to documented clinical information. Although errors of cognitive underspecification arise at the sharp end with the care provider, effective management is dependent upon system redesign that mitigates the latent contributory factors. Cognitive underspecification is ubiquitous whenever communication occurs. Accurate identification is essential if effective system redesign is to occur.

Improved prediction of hardwood tree biomass derived from wood density estimates and form factors for whole trees

Treesearch

David W. MacFarlane; Neil R. Ver Planck

2012-01-01

Data from hardwood trees in Michigan were analyzed to investigate how differences in whole-tree form and wood density between trees of different stem diameter relate to residual error in standard-type biomass equations. The results suggested that whole-tree wood density, measured at breast height, explained a significant proportion of residual error in standard-type...

The Relationship between Mean Square Differences and Standard Error of Measurement: Comment on Barchard (2012)

ERIC Educational Resources Information Center

Pan, Tianshu; Yin, Yue

2012-01-01

In the discussion of mean square difference (MSD) and standard error of measurement (SEM), Barchard (2012) concluded that the MSD between 2 sets of test scores is greater than 2(SEM)[superscript 2] and SEM underestimates the score difference between 2 tests when the 2 tests are not parallel. This conclusion has limitations for 2 reasons. First,…

Empirical Synthesis of the Effect of Standard Error of Measurement on Decisions Made within Brief Experimental Analyses of Reading Fluency

ERIC Educational Resources Information Center

Burns, Matthew K.; Taylor, Crystal N.; Warmbold-Brann, Kristy L.; Preast, June L.; Hosp, John L.; Ford, Jeremy W.

2017-01-01

Intervention researchers often use curriculum-based measurement of reading fluency (CBM-R) with a brief experimental analysis (BEA) to identify an effective intervention for individual students. The current study synthesized data from 22 studies that used CBM-R data within a BEA by computing the standard error of measure (SEM) for the median data…

A Comparison of Kernel Equating and Traditional Equipercentile Equating Methods and the Parametric Bootstrap Methods for Estimating Standard Errors in Equipercentile Equating

ERIC Educational Resources Information Center

Choi, Sae Il

2009-01-01

This study used simulation (a) to compare the kernel equating method to traditional equipercentile equating methods under the equivalent-groups (EG) design and the nonequivalent-groups with anchor test (NEAT) design and (b) to apply the parametric bootstrap method for estimating standard errors of equating. A two-parameter logistic item response…

Comparison of various error functions in predicting the optimum isotherm by linear and non-linear regression analysis for the sorption of basic red 9 by activated carbon.

PubMed

Kumar, K Vasanth; Porkodi, K; Rocha, F

2008-01-15

A comparison of linear and non-linear regression method in selecting the optimum isotherm was made to the experimental equilibrium data of basic red 9 sorption by activated carbon. The r(2) was used to select the best fit linear theoretical isotherm. In the case of non-linear regression method, six error functions namely coefficient of determination (r(2)), hybrid fractional error function (HYBRID), Marquardt's percent standard deviation (MPSD), the average relative error (ARE), sum of the errors squared (ERRSQ) and sum of the absolute errors (EABS) were used to predict the parameters involved in the two and three parameter isotherms and also to predict the optimum isotherm. Non-linear regression was found to be a better way to obtain the parameters involved in the isotherms and also the optimum isotherm. For two parameter isotherm, MPSD was found to be the best error function in minimizing the error distribution between the experimental equilibrium data and predicted isotherms. In the case of three parameter isotherm, r(2) was found to be the best error function to minimize the error distribution structure between experimental equilibrium data and theoretical isotherms. The present study showed that the size of the error function alone is not a deciding factor to choose the optimum isotherm. In addition to the size of error function, the theory behind the predicted isotherm should be verified with the help of experimental data while selecting the optimum isotherm. A coefficient of non-determination, K(2) was explained and was found to be very useful in identifying the best error function while selecting the optimum isotherm.

Unit of Measurement Used and Parent Medication Dosing Errors

PubMed Central

Dreyer, Benard P.; Ugboaja, Donna C.; Sanchez, Dayana C.; Paul, Ian M.; Moreira, Hannah A.; Rodriguez, Luis; Mendelsohn, Alan L.

2014-01-01

BACKGROUND AND OBJECTIVES: Adopting the milliliter as the preferred unit of measurement has been suggested as a strategy to improve the clarity of medication instructions; teaspoon and tablespoon units may inadvertently endorse nonstandard kitchen spoon use. We examined the association between unit used and parent medication errors and whether nonstandard instruments mediate this relationship. METHODS: Cross-sectional analysis of baseline data from a larger study of provider communication and medication errors. English- or Spanish-speaking parents (n = 287) whose children were prescribed liquid medications in 2 emergency departments were enrolled. Medication error defined as: error in knowledge of prescribed dose, error in observed dose measurement (compared to intended or prescribed dose); >20% deviation threshold for error. Multiple logistic regression performed adjusting for parent age, language, country, race/ethnicity, socioeconomic status, education, health literacy (Short Test of Functional Health Literacy in Adults); child age, chronic disease; site. RESULTS: Medication errors were common: 39.4% of parents made an error in measurement of the intended dose, 41.1% made an error in the prescribed dose. Furthermore, 16.7% used a nonstandard instrument. Compared with parents who used milliliter-only, parents who used teaspoon or tablespoon units had twice the odds of making an error with the intended (42.5% vs 27.6%, P = .02; adjusted odds ratio=2.3; 95% confidence interval, 1.2–4.4) and prescribed (45.1% vs 31.4%, P = .04; adjusted odds ratio=1.9; 95% confidence interval, 1.03–3.5) dose; associations greater for parents with low health literacy and non–English speakers. Nonstandard instrument use partially mediated teaspoon and tablespoon–associated measurement errors. CONCLUSIONS: Findings support a milliliter-only standard to reduce medication errors. PMID:25022742

Unit of measurement used and parent medication dosing errors.

PubMed

Yin, H Shonna; Dreyer, Benard P; Ugboaja, Donna C; Sanchez, Dayana C; Paul, Ian M; Moreira, Hannah A; Rodriguez, Luis; Mendelsohn, Alan L

2014-08-01

Adopting the milliliter as the preferred unit of measurement has been suggested as a strategy to improve the clarity of medication instructions; teaspoon and tablespoon units may inadvertently endorse nonstandard kitchen spoon use. We examined the association between unit used and parent medication errors and whether nonstandard instruments mediate this relationship. Cross-sectional analysis of baseline data from a larger study of provider communication and medication errors. English- or Spanish-speaking parents (n = 287) whose children were prescribed liquid medications in 2 emergency departments were enrolled. Medication error defined as: error in knowledge of prescribed dose, error in observed dose measurement (compared to intended or prescribed dose); >20% deviation threshold for error. Multiple logistic regression performed adjusting for parent age, language, country, race/ethnicity, socioeconomic status, education, health literacy (Short Test of Functional Health Literacy in Adults); child age, chronic disease; site. Medication errors were common: 39.4% of parents made an error in measurement of the intended dose, 41.1% made an error in the prescribed dose. Furthermore, 16.7% used a nonstandard instrument. Compared with parents who used milliliter-only, parents who used teaspoon or tablespoon units had twice the odds of making an error with the intended (42.5% vs 27.6%, P = .02; adjusted odds ratio=2.3; 95% confidence interval, 1.2-4.4) and prescribed (45.1% vs 31.4%, P = .04; adjusted odds ratio=1.9; 95% confidence interval, 1.03-3.5) dose; associations greater for parents with low health literacy and non-English speakers. Nonstandard instrument use partially mediated teaspoon and tablespoon-associated measurement errors. Findings support a milliliter-only standard to reduce medication errors. Copyright © 2014 by the American Academy of Pediatrics.

Cirrus Cloud Retrieval Using Infrared Sounding Data: Multilevel Cloud Errors.

NASA Astrophysics Data System (ADS)

Baum, Bryan A.; Wielicki, Bruce A.

1994-01-01

In this study we perform an error analysis for cloud-top pressure retrieval using the High-Resolution Infrared Radiometric Sounder (HIRS/2) 15-µm CO2 channels for the two-layer case of transmissive cirrus overlying an overcast, opaque stratiform cloud. This analysis includes standard deviation and bias error due to instrument noise and the presence of two cloud layers, the lower of which is opaque. Instantaneous cloud pressure retrieval errors are determined for a range of cloud amounts (0.1 1.0) and cloud-top pressures (850250 mb). Large cloud-top pressure retrieval errors are found to occur when a lower opaque layer is present underneath an upper transmissive cloud layer in the satellite field of view (FOV). Errors tend to increase with decreasing upper-cloud elective cloud amount and with decreasing cloud height (increasing pressure). Errors in retrieved upper-cloud pressure result in corresponding errors in derived effective cloud amount. For the case in which a HIRS FOV has two distinct cloud layers, the difference between the retrieved and actual cloud-top pressure is positive in all casts, meaning that the retrieved upper-cloud height is lower than the actual upper-cloud height. In addition, errors in retrieved cloud pressure are found to depend upon the lapse rate between the low-level cloud top and the surface. We examined which sounder channel combinations would minimize the total errors in derived cirrus cloud height caused by instrument noise and by the presence of a lower-level cloud. We find that while the sounding channels that peak between 700 and 1000 mb minimize random errors, the sounding channels that peak at 300—500 mb minimize bias errors. For a cloud climatology, the bias errors are most critical.

Study on Network Error Analysis and Locating based on Integrated Information Decision System

NASA Astrophysics Data System (ADS)

Yang, F.; Dong, Z. H.

2017-10-01

Integrated information decision system (IIDS) integrates multiple sub-system developed by many facilities, including almost hundred kinds of software, which provides with various services, such as email, short messages, drawing and sharing. Because the under-layer protocols are different, user standards are not unified, many errors are occurred during the stages of setup, configuration, and operation, which seriously affect the usage. Because the errors are various, which may be happened in different operation phases, stages, TCP/IP communication protocol layers, sub-system software, it is necessary to design a network error analysis and locating tool for IIDS to solve the above problems. This paper studies on network error analysis and locating based on IIDS, which provides strong theory and technology supports for the running and communicating of IIDS.

Refractive errors and schizophrenia.

PubMed

Caspi, Asaf; Vishne, Tali; Reichenberg, Abraham; Weiser, Mark; Dishon, Ayelet; Lubin, Gadi; Shmushkevitz, Motti; Mandel, Yossi; Noy, Shlomo; Davidson, Michael

2009-02-01

Refractive errors (myopia, hyperopia and amblyopia), like schizophrenia, have a strong genetic cause, and dopamine has been proposed as a potential mediator in their pathophysiology. The present study explored the association between refractive errors in adolescence and schizophrenia, and the potential familiality of this association. The Israeli Draft Board carries a mandatory standardized visual accuracy assessment. 678,674 males consecutively assessed by the Draft Board and found to be psychiatrically healthy at age 17 were followed for psychiatric hospitalization with schizophrenia using the Israeli National Psychiatric Hospitalization Case Registry. Sib-ships were also identified within the cohort. There was a negative association between refractive errors and later hospitalization for schizophrenia. Future male schizophrenia patients were two times less likely to have refractive errors compared with never-hospitalized individuals, controlling for intelligence, years of education and socioeconomic status [adjusted Hazard Ratio=.55; 95% confidence interval .35-.85]. The non-schizophrenic male siblings of schizophrenia patients also had lower prevalence of refractive errors compared to never-hospitalized individuals. Presence of refractive errors in adolescence is related to lower risk for schizophrenia. The familiality of this association suggests that refractive errors may be associated with the genetic liability to schizophrenia.

Route learning in amnesia: a comparison of trial-and-error and errorless learning in patients with the Korsakoff syndrome.

PubMed

Kessels, Roy P C; van Loon, Eke; Wester, Arie J

2007-10-01

To examine the errorless learning approach using a procedural memory task (i.e. learning of actual routes) in patients with amnesia, as compared to trial-and-error learning. Counterbalanced self-controlled cases series. Psychiatric hospital (Korsakoff clinic). A convenience sample of 10 patients with the Korsakoff amnestic syndrome. All patients learned a route in four sessions on separate days using an errorless approach and a different route using trial-and-error. Error rate was scored during route learning and standard neuro-psychological tests were administered (i.e. subtest route recall of the Rivermead Behavioural Memory Test (RBMT) and the Dutch version of the California Verbal Learning Test (VLGT)). A significant learning effect was found in the trial-and-error condition over consecutive sessions (P = 0.006), but no performance difference was found between errorless and trial-and-error learning of the routes. VLGT performance was significantly correlated with a trial-and-error advantage (P < 0.05); no significant correlation was found between the RBMT subtest and the learning conditions. Errorless learning was no more successful than trial-and-error learning of a procedural spatial task in patients with the Korsakoff syndrome (severe amnesia).

A multifaceted program for improving quality of care in intensive care units: IATROREF study.

PubMed

Garrouste-Orgeas, Maite; Soufir, Lilia; Tabah, Alexis; Schwebel, Carole; Vesin, Aurelien; Adrie, Christophe; Thuong, Marie; Timsit, Jean Francois

2012-02-01

To test the effects of three multifaceted safety programs designed to decrease insulin administration errors, anticoagulant prescription and administration errors, and errors leading to accidental removal of endotracheal tubes and central venous catheters, respectively. Medical errors and adverse events are associated with increased mortality in intensive care patients, indicating an urgent need for prevention programs. Multicenter cluster-randomized study. One medical intensive care unit in a university hospital and two medical-surgical intensive care units in community hospitals belonging to the Outcomerea Study Group. Consecutive patients >18 yrs admitted from January 2007 to January 2008 to the intensive care units. We tested three multifaceted safety programs vs. standard care in random order, each over 2.5 months, after a 1.5-month observation period. Incidence rates of medical errors/1000 patient-days in the multifaceted safety program and standard-care groups were compared using adjusted hierarchical models. In 2117 patients with 15,014 patient-days, 8520 medical errors (567.5/1000 patient-days) were reported, including 1438 adverse events (16.9%, 95.8/1000 patient-days). The insulin multifaceted safety program significantly decreased errors during implementation (risk ratio 0.65; 95% confidence interval [CI] 0.52-0.82; p = .0003) and after implementation (risk ratio 0.51; 95% CI 0.35-0.73; p = .0004). A significant Hawthorne effect was found. The accidental tube/catheter removal multifaceted safety program decreased errors significantly during implementation (odds ratio [OR] 0.34; 95% CI 0.15-0.81; p = .01]) and nonsignificantly after implementation (OR 1.65; 95% CI 0.78-3.48). The anticoagulation multifaceted safety program was not significantly effective (OR 0.64; 95% CI 0.26-1.59) but produced a significant Hawthorne effect. A multifaceted program was effective in preventing insulin errors and accidental tube/catheter removal. Significant Hawthorne effects occurred, emphasizing the need for appropriately designed studies before definitively implementing strategies. clinicaltrials.gov Identifier: NCT00461461.

Integrating Map Algebra and Statistical Modeling for Spatio- Temporal Analysis of Monthly Mean Daily Incident Photosynthetically Active Radiation (PAR) over a Complex Terrain.

PubMed

Evrendilek, Fatih

2007-12-12

This study aims at quantifying spatio-temporal dynamics of monthly mean dailyincident photosynthetically active radiation (PAR) over a vast and complex terrain such asTurkey. The spatial interpolation method of universal kriging, and the combination ofmultiple linear regression (MLR) models and map algebra techniques were implemented togenerate surface maps of PAR with a grid resolution of 500 x 500 m as a function of fivegeographical and 14 climatic variables. Performance of the geostatistical and MLR modelswas compared using mean prediction error (MPE), root-mean-square prediction error(RMSPE), average standard prediction error (ASE), mean standardized prediction error(MSPE), root-mean-square standardized prediction error (RMSSPE), and adjustedcoefficient of determination (R² adj. ). The best-fit MLR- and universal kriging-generatedmodels of monthly mean daily PAR were validated against an independent 37-year observeddataset of 35 climate stations derived from 160 stations across Turkey by the Jackknifingmethod. The spatial variability patterns of monthly mean daily incident PAR were moreaccurately reflected in the surface maps created by the MLR-based models than in thosecreated by the universal kriging method, in particular, for spring (May) and autumn(November). The MLR-based spatial interpolation algorithms of PAR described in thisstudy indicated the significance of the multifactor approach to understanding and mappingspatio-temporal dynamics of PAR for a complex terrain over meso-scales.

Uncertainty Propagation in an Ecosystem Nutrient Budget.

EPA Science Inventory

New aspects and advancements in classical uncertainty propagation methods were used to develop a nutrient budget with associated error for a northern Gulf of Mexico coastal embayment. Uncertainty was calculated for budget terms by propagating the standard error and degrees of fr...

Characteristics of advanced hydrogen maser frequency standards

NASA Technical Reports Server (NTRS)

Peters, H. E.

1973-01-01

Measurements with several operational atomic hydrogen maser standards have been made which illustrate the fundamental characteristics of the maser as well as the analysability of the corrections which are made to relate the oscillation frequency to the free, unperturbed, hydrogen standard transition frequency. Sources of the most important perturbations, and the magnitude of the associated errors, are discussed. A variable volume storage bulb hydrogen maser is also illustrated which can provide on the order of 2 parts in 10 to the 14th power or better accuracy in evaluating the wall shift. Since the other basic error sources combined contribute no more than approximately 1 part in 10 to the 14th power uncertainty, the variable volume storage bulb hydrogen maser will have net intrinsic accuracy capability of the order of 2 parts in 10 to the 14th power or better. This is an order of magnitude less error than anticipated with cesium standards and is comparable to the basic limit expected for a free atom hydrogen beam resonance standard.

Improving estimates of streamflow characteristics by using Landsat-1 imagery

USGS Publications Warehouse

Hollyday, Este F.

1976-01-01

Imagery from the first Earth Resources Technology Satellite (renamed Landsat-1) was used to discriminate physical features of drainage basins in an effort to improve equations used to estimate streamflow characteristics at gaged and ungaged sites. Records of 20 gaged basins in the Delmarva Peninsula of Maryland, Delaware, and Virginia were analyzed for 40 statistical streamflow characteristics. Equations relating these characteristics to basin characteristics were obtained by a technique of multiple linear regression. A control group of equations contains basin characteristics derived from maps. An experimental group of equations contains basin characteristics derived from maps and imagery. Characteristics from imagery were forest, riparian (streambank) vegetation, water, and combined agricultural and urban land use. These basin characteristics were isolated photographically by techniques of film-density discrimination. The area of each characteristic in each basin was measured photometrically. Comparison of equations in the control group with corresponding equations in the experimental group reveals that for 12 out of 40 equations the standard error of estimate was reduced by more than 10 percent. As an example, the standard error of estimate of the equation for the 5-year recurrence-interval flood peak was reduced from 46 to 32 percent. Similarly, the standard error of the equation for the mean monthly flow for September was reduced from 32 to 24 percent, the standard error for the 7-day, 2-year recurrence low flow was reduced from 136 to 102 percent, and the standard error for the 3-day, 2-year flood volume was reduced from 30 to 12 percent. It is concluded that data from Landsat imagery can substantially improve the accuracy of estimates of some streamflow characteristics at sites in the Delmarva Peninsula.

Evaluation of random errors in Williams’ series coefficients obtained with digital image correlation

NASA Astrophysics Data System (ADS)

Lychak, Oleh V.; Holyns'kiy, Ivan S.

2016-03-01

The use of the Williams’ series parameters for fracture analysis requires valid information about their error values. The aim of this investigation is the development of the method for estimation of the standard deviation of random errors of the Williams’ series parameters, obtained from the measured components of the stress field. Also, the criteria for choosing the optimal number of terms in the truncated Williams’ series for derivation of their parameters with minimal errors is proposed. The method was used for the evaluation of the Williams’ parameters, obtained from the data, and measured by the digital image correlation technique for testing a three-point bending specimen.

A-Posteriori Error Estimation for Hyperbolic Conservation Laws with Constraint

NASA Technical Reports Server (NTRS)

Barth, Timothy

2004-01-01

This lecture considers a-posteriori error estimates for the numerical solution of conservation laws with time invariant constraints such as those arising in magnetohydrodynamics (MHD) and gravitational physics. Using standard duality arguments, a-posteriori error estimates for the discontinuous Galerkin finite element method are then presented for MHD with solenoidal constraint. From these estimates, a procedure for adaptive discretization is outlined. A taxonomy of Green's functions for the linearized MHD operator is given which characterizes the domain of dependence for pointwise errors. The extension to other constrained systems such as the Einstein equations of gravitational physics are then considered. Finally, future directions and open problems are discussed.

A MIMO radar quadrature and multi-channel amplitude-phase error combined correction method based on cross-correlation

NASA Astrophysics Data System (ADS)

Yun, Lingtong; Zhao, Hongzhong; Du, Mengyuan

2018-04-01

Quadrature and multi-channel amplitude-phase error have to be compensated in the I/Q quadrature sampling and signal through multi-channel. A new method that it doesn't need filter and standard signal is presented in this paper. And it can combined estimate quadrature and multi-channel amplitude-phase error. The method uses cross-correlation and amplitude ratio between the signal to estimate the two amplitude-phase errors simply and effectively. And the advantages of this method are verified by computer simulation. Finally, the superiority of the method is also verified by measure data of outfield experiments.

Advanced error diagnostics of the CMAQ and Chimere modelling systems within the AQMEII3 model evaluation framework

NASA Astrophysics Data System (ADS)

Solazzo, Efisio; Hogrefe, Christian; Colette, Augustin; Garcia-Vivanco, Marta; Galmarini, Stefano

2017-09-01

The work here complements the overview analysis of the modelling systems participating in the third phase of the Air Quality Model Evaluation International Initiative (AQMEII3) by focusing on the performance for hourly surface ozone by two modelling systems, Chimere for Europe and CMAQ for North America. The evaluation strategy outlined in the course of the three phases of the AQMEII activity, aimed to build up a diagnostic methodology for model evaluation, is pursued here and novel diagnostic methods are proposed. In addition to evaluating the base case simulation in which all model components are configured in their standard mode, the analysis also makes use of sensitivity simulations in which the models have been applied by altering and/or zeroing lateral boundary conditions, emissions of anthropogenic precursors, and ozone dry deposition. To help understand of the causes of model deficiencies, the error components (bias, variance, and covariance) of the base case and of the sensitivity runs are analysed in conjunction with timescale considerations and error modelling using the available error fields of temperature, wind speed, and NOx concentration. The results reveal the effectiveness and diagnostic power of the methods devised (which remains the main scope of this study), allowing the detection of the timescale and the fields that the two models are most sensitive to. The representation of planetary boundary layer (PBL) dynamics is pivotal to both models. In particular, (i) the fluctuations slower than ˜ 1.5 days account for 70-85 % of the mean square error of the full (undecomposed) ozone time series; (ii) a recursive, systematic error with daily periodicity is detected, responsible for 10-20 % of the quadratic total error; (iii) errors in representing the timing of the daily transition between stability regimes in the PBL are responsible for a covariance error as large as 9 ppb (as much as the standard deviation of the network-average ozone observations in summer in both Europe and North America); (iv) the CMAQ ozone error has a weak/negligible dependence on the errors in NO2, while the error in NO2 significantly impacts the ozone error produced by Chimere; (v) the response of the models to variations of anthropogenic emissions and boundary conditions show a pronounced spatial heterogeneity, while the seasonal variability of the response is found to be less marked. Only during the winter season does the zeroing of boundary values for North America produce a spatially uniform deterioration of the model accuracy across the majority of the continent.

Demonstrating the robustness of population surveillance data: implications of error rates on demographic and mortality estimates.

PubMed

Fottrell, Edward; Byass, Peter; Berhane, Yemane

2008-03-25

As in any measurement process, a certain amount of error may be expected in routine population surveillance operations such as those in demographic surveillance sites (DSSs). Vital events are likely to be missed and errors made no matter what method of data capture is used or what quality control procedures are in place. The extent to which random errors in large, longitudinal datasets affect overall health and demographic profiles has important implications for the role of DSSs as platforms for public health research and clinical trials. Such knowledge is also of particular importance if the outputs of DSSs are to be extrapolated and aggregated with realistic margins of error and validity. This study uses the first 10-year dataset from the Butajira Rural Health Project (BRHP) DSS, Ethiopia, covering approximately 336,000 person-years of data. Simple programmes were written to introduce random errors and omissions into new versions of the definitive 10-year Butajira dataset. Key parameters of sex, age, death, literacy and roof material (an indicator of poverty) were selected for the introduction of errors based on their obvious importance in demographic and health surveillance and their established significant associations with mortality. Defining the original 10-year dataset as the 'gold standard' for the purposes of this investigation, population, age and sex compositions and Poisson regression models of mortality rate ratios were compared between each of the intentionally erroneous datasets and the original 'gold standard' 10-year data. The composition of the Butajira population was well represented despite introducing random errors, and differences between population pyramids based on the derived datasets were subtle. Regression analyses of well-established mortality risk factors were largely unaffected even by relatively high levels of random errors in the data. The low sensitivity of parameter estimates and regression analyses to significant amounts of randomly introduced errors indicates a high level of robustness of the dataset. This apparent inertia of population parameter estimates to simulated errors is largely due to the size of the dataset. Tolerable margins of random error in DSS data may exceed 20%. While this is not an argument in favour of poor quality data, reducing the time and valuable resources spent on detecting and correcting random errors in routine DSS operations may be justifiable as the returns from such procedures diminish with increasing overall accuracy. The money and effort currently spent on endlessly correcting DSS datasets would perhaps be better spent on increasing the surveillance population size and geographic spread of DSSs and analysing and disseminating research findings.

Measurements of stem diameter: implications for individual- and stand-level errors.

PubMed

Paul, Keryn I; Larmour, John S; Roxburgh, Stephen H; England, Jacqueline R; Davies, Micah J; Luck, Hamish D

2017-08-01

Stem diameter is one of the most common measurements made to assess the growth of woody vegetation, and the commercial and environmental benefits that it provides (e.g. wood or biomass products, carbon sequestration, landscape remediation). Yet inconsistency in its measurement is a continuing source of error in estimates of stand-scale measures such as basal area, biomass, and volume. Here we assessed errors in stem diameter measurement through repeated measurements of individual trees and shrubs of varying size and form (i.e. single- and multi-stemmed) across a range of contrasting stands, from complex mixed-species plantings to commercial single-species plantations. We compared a standard diameter tape with a Stepped Diameter Gauge (SDG) for time efficiency and measurement error. Measurement errors in diameter were slightly (but significantly) influenced by size and form of the tree or shrub, and stem height at which the measurement was made. Compared to standard tape measurement, the mean systematic error with SDG measurement was only -0.17 cm, but varied between -0.10 and -0.52 cm. Similarly, random error was relatively large, with standard deviations (and percentage coefficients of variation) averaging only 0.36 cm (and 3.8%), but varying between 0.14 and 0.61 cm (and 1.9 and 7.1%). However, at the stand scale, sampling errors (i.e. how well individual trees or shrubs selected for measurement of diameter represented the true stand population in terms of the average and distribution of diameter) generally had at least a tenfold greater influence on random errors in basal area estimates than errors in diameter measurements. This supports the use of diameter measurement tools that have high efficiency, such as the SDG. Use of the SDG almost halved the time required for measurements compared to the diameter tape. Based on these findings, recommendations include the following: (i) use of a tape to maximise accuracy when developing allometric models, or when monitoring relatively small changes in permanent sample plots (e.g. National Forest Inventories), noting that care is required in irregular-shaped, large-single-stemmed individuals, and (ii) use of a SDG to maximise efficiency when using inventory methods to assess basal area, and hence biomass or wood volume, at the stand scale (i.e. in studies of impacts of management or site quality) where there are budgetary constraints, noting the importance of sufficient sample sizes to ensure that the population sampled represents the true population.

North Alabama Lightning Mapping Array (LMA): VHF Source Retrieval Algorithm and Error Analyses

NASA Technical Reports Server (NTRS)

Koshak, W. J.; Solakiewicz, R. J.; Blakeslee, R. J.; Goodman, S. J.; Christian, H. J.; Hall, J.; Bailey, J.; Krider, E. P.; Bateman, M. G.; Boccippio, D.

2003-01-01

Two approaches are used to characterize how accurately the North Alabama Lightning Mapping Array (LMA) is able to locate lightning VHF sources in space and in time. The first method uses a Monte Carlo computer simulation to estimate source retrieval errors. The simulation applies a VHF source retrieval algorithm that was recently developed at the NASA Marshall Space Flight Center (MSFC) and that is similar, but not identical to, the standard New Mexico Tech retrieval algorithm. The second method uses a purely theoretical technique (i.e., chi-squared Curvature Matrix Theory) to estimate retrieval errors. Both methods assume that the LMA system has an overall rms timing error of 50 ns, but all other possible errors (e.g., multiple sources per retrieval attempt) are neglected. The detailed spatial distributions of retrieval errors are provided. Given that the two methods are completely independent of one another, it is shown that they provide remarkably similar results. However, for many source locations, the Curvature Matrix Theory produces larger altitude error estimates than the (more realistic) Monte Carlo simulation.

Errors in the Extra-Analytical Phases of Clinical Chemistry Laboratory Testing.

PubMed

Zemlin, Annalise E

2018-04-01

The total testing process consists of various phases from the pre-preanalytical to the post-postanalytical phase, the so-called brain-to-brain loop. With improvements in analytical techniques and efficient quality control programmes, most laboratory errors now occur in the extra-analytical phases. There has been recent interest in these errors with numerous publications highlighting their effect on service delivery, patient care and cost. This interest has led to the formation of various working groups whose mission is to develop standardized quality indicators which can be used to measure the performance of service of these phases. This will eventually lead to the development of external quality assessment schemes to monitor these phases in agreement with ISO15189:2012 recommendations. This review focuses on potential errors in the extra-analytical phases of clinical chemistry laboratory testing, some of the studies performed to assess the severity and impact of these errors and processes that are in place to address these errors. The aim of this review is to highlight the importance of these errors for the requesting clinician.

Goldmann tonometer error correcting prism: clinical evaluation.

PubMed

McCafferty, Sean; Lim, Garrett; Duncan, William; Enikov, Eniko T; Schwiegerling, Jim; Levine, Jason; Kew, Corin

2017-01-01

Clinically evaluate a modified applanating surface Goldmann tonometer prism designed to substantially negate errors due to patient variability in biomechanics. A modified Goldmann prism with a correcting applanation tonometry surface (CATS) was mathematically optimized to minimize the intraocular pressure (IOP) measurement error due to patient variability in corneal thickness, stiffness, curvature, and tear film adhesion force. A comparative clinical study of 109 eyes measured IOP with CATS and Goldmann prisms. The IOP measurement differences between the CATS and Goldmann prisms were correlated to corneal thickness, hysteresis, and curvature. The CATS tonometer prism in correcting for Goldmann central corneal thickness (CCT) error demonstrated a reduction to <±2 mmHg in 97% of a standard CCT population. This compares to only 54% with CCT error <±2 mmHg using the Goldmann prism. Equal reductions of ~50% in errors due to corneal rigidity and curvature were also demonstrated. The results validate the CATS prism's improved accuracy and expected reduced sensitivity to Goldmann errors without IOP bias as predicted by mathematical modeling. The CATS replacement for the Goldmann prism does not change Goldmann measurement technique or interpretation.

Error Consistency Analysis Scheme for Infrared Ultraspectral Sounding Retrieval Error Budget Estimation

NASA Technical Reports Server (NTRS)

Zhou, Daniel K.; Larar, Allen M.; Liu, Xu; Smith, William L.; Strow, Larry, L.

2013-01-01

Great effort has been devoted towards validating geophysical parameters retrieved from ultraspectral infrared radiances obtained from satellite remote sensors. An error consistency analysis scheme (ECAS), utilizing fast radiative transfer model (RTM) forward and inverse calculations, has been developed to estimate the error budget in terms of mean difference and standard deviation of error in both spectral radiance and retrieval domains. The retrieval error is assessed through ECAS without relying on other independent measurements such as radiosonde data. ECAS establishes a link between the accuracies of radiances and retrieved geophysical parameters. ECAS can be applied to measurements from any ultraspectral instrument and any retrieval scheme with its associated RTM. In this manuscript, ECAS is described and demonstrated with measurements from the MetOp-A satellite Infrared Atmospheric Sounding Interferometer (IASI). This scheme can be used together with other validation methodologies to give a more definitive characterization of the error and/or uncertainty of geophysical parameters retrieved from ultraspectral radiances observed from current and future satellite remote sensors such as IASI, the Atmospheric Infrared Sounder (AIRS), and the Cross-track Infrared Sounder (CrIS).

Error-Monitoring in Response to Social Stimuli in Individuals with Higher-Functioning Autism Spectrum Disorder

PubMed Central

McMahon, Camilla M.; Henderson, Heather A.

2014-01-01

Error-monitoring, or the ability to recognize one's mistakes and implement behavioral changes to prevent further mistakes, may be impaired in individuals with Autism Spectrum Disorder (ASD). Children and adolescents (ages 9-19) with ASD (n = 42) and typical development (n = 42) completed two face processing tasks that required discrimination of either the gender or affect of standardized face stimuli. Post-error slowing and the difference in Error-Related Negativity amplitude between correct and incorrect responses (ERNdiff) were used to index error-monitoring ability. Overall, ERNdiff increased with age. On the Gender Task, individuals with ASD had a smaller ERNdiff than individuals with typical development; however, on the Affect Task, there were no significant diagnostic group differences on ERNdiff. Individuals with ASD may have ERN amplitudes similar to those observed in individuals with typical development in more social contexts compared to less social contexts due to greater consequences for errors, more effortful processing, and/or reduced processing efficiency in these contexts. Across all participants, more post-error slowing on the Affect Task was associated with better social cognitive skills. PMID:25066088

Comparative Cost-Effectiveness Analysis of Three Different Automated Medication Systems Implemented in a Danish Hospital Setting.

PubMed

Risør, Bettina Wulff; Lisby, Marianne; Sørensen, Jan

2018-02-01

Automated medication systems have been found to reduce errors in the medication process, but little is known about the cost-effectiveness of such systems. The objective of this study was to perform a model-based indirect cost-effectiveness comparison of three different, real-world automated medication systems compared with current standard practice. The considered automated medication systems were a patient-specific automated medication system (psAMS), a non-patient-specific automated medication system (npsAMS), and a complex automated medication system (cAMS). The economic evaluation used original effect and cost data from prospective, controlled, before-and-after studies of medication systems implemented at a Danish hematological ward and an acute medical unit. Effectiveness was described as the proportion of clinical and procedural error opportunities that were associated with one or more errors. An error was defined as a deviation from the electronic prescription, from standard hospital policy, or from written procedures. The cost assessment was based on 6-month standardization of observed cost data. The model-based comparative cost-effectiveness analyses were conducted with system-specific assumptions of the effect size and costs in scenarios with consumptions of 15,000, 30,000, and 45,000 doses per 6-month period. With 30,000 doses the cost-effectiveness model showed that the cost-effectiveness ratio expressed as the cost per avoided clinical error was €24 for the psAMS, €26 for the npsAMS, and €386 for the cAMS. Comparison of the cost-effectiveness of the three systems in relation to different valuations of an avoided error showed that the psAMS was the most cost-effective system regardless of error type or valuation. The model-based indirect comparison against the conventional practice showed that psAMS and npsAMS were more cost-effective than the cAMS alternative, and that psAMS was more cost-effective than npsAMS.

Measures of rowing performance.

PubMed

Smith, T Brett; Hopkins, Will G

2012-04-01

Accurate measures of performance are important for assessing competitive athletes in practi~al and research settings. We present here a review of rowing performance measures, focusing on the errors in these measures and the implications for testing rowers. The yardstick for assessing error in a performance measure is the random variation (typical or standard error of measurement) in an elite athlete's competitive performance from race to race: ∼1.0% for time in 2000 m rowing events. There has been little research interest in on-water time trials for assessing rowing performance, owing to logistic difficulties and environmental perturbations in performance time with such tests. Mobile ergometry via instrumented oars or rowlocks should reduce these problems, but the associated errors have not yet been reported. Measurement of boat speed to monitor on-water training performance is common; one device based on global positioning system (GPS) technology contributes negligible extra random error (0.2%) in speed measured over 2000 m, but extra error is substantial (1-10%) with other GPS devices or with an impeller, especially over shorter distances. The problems with on-water testing have led to widespread use of the Concept II rowing ergometer. The standard error of the estimate of on-water 2000 m time predicted by 2000 m ergometer performance was 2.6% and 7.2% in two studies, reflecting different effects of skill, body mass and environment in on-water versus ergometer performance. However, well trained rowers have a typical error in performance time of only ∼0.5% between repeated 2000 m time trials on this ergometer, so such trials are suitable for tracking changes in physiological performance and factors affecting it. Many researchers have used the 2000 m ergometer performance time as a criterion to identify other predictors of rowing performance. Standard errors of the estimate vary widely between studies even for the same predictor, but the lowest errors (~1-2%) have been observed for peak power output in an incremental test, some measures of lactate threshold and measures of 30-second all-out power. Some of these measures also have typical error between repeated tests suitably low for tracking changes. Combining measures via multiple linear regression needs further investigation. In summary, measurement of boat speed, especially with a good GPS device, has adequate precision for monitoring training performance, but adjustment for environmental effects needs to be investigated. Time trials on the Concept II ergometer provide accurate estimates of a rower's physiological ability to output power, and some submaximal and brief maximal ergometer performance measures can be used frequently to monitor changes in this ability. On-water performance measured via instrumented skiffs that determine individual power output may eventually surpass measures derived from the Concept II.

Magnetic Field Measurements of the Spotted Yellow Dwarf DE Boo During 2001-2004

NASA Astrophysics Data System (ADS)

Plachinda, S.; Baklanova, D.; Butkovskaya, V.; Pankov, N.

2017-06-01

Spectropolarimetric observations of DE Boo have been performed at Crimean astrophysical observatory during 18 nights in 2001-2004. We present the result of the longitudinal magnetic field measurements on this star. The magnetic field varies from +44 G to -36 G with mean Standard Error (SE) of 8.2 G. For full array of the magnetic field measurements the difference between experimental errors and Monte Carlo errors is not statistically significant.

Psycho-Motor and Error Enabled Simulations: Modeling Vulnerable Skills in the Pre-Mastery Phase Medical Practice Initiative Procedural Skill Decay and Maintenance (MPI-PSD)

DTIC Science & Technology

2014-04-01

laparoscopic ventral hernia repair. Additional simulation stations were added to the standards and purchases (including a motion tracking system) were...framework for laparoscopic ventral hernia; Incorporation of error-based simulators into an exit assessment of chief surgical residents; Development of...simulating a laparoscopic ventral hernia (LVH) repair. Based on collected data, the lab worked to finalize the incorporation of error-based simulators

Estimating the Imputed Social Cost of Errors of Measurement.

DTIC Science & Technology

1983-10-01

social cost of an error of measurement in the score on a unidimensional test, an asymptotic method, based on item response theory, is developed for...11111111 ij MICROCOPY RESOLUTION TEST CHART NATIONAL BUREAU OF STANDARDS-1963-A.5. ,,, I v.P I RR-83-33-ONR 4ESTIMATING THE IMPUTED SOCIAL COST S OF... SOCIAL COST OF ERRORS OF MEASUREMENT Frederic M. Lord This research was sponsored in part by the Personnel and Training Research Programs Psychological

Mass measurement errors of Fourier-transform mass spectrometry (FTMS): distribution, recalibration, and application.

PubMed

Zhang, Jiyang; Ma, Jie; Dou, Lei; Wu, Songfeng; Qian, Xiaohong; Xie, Hongwei; Zhu, Yunping; He, Fuchu

2009-02-01

The hybrid linear trap quadrupole Fourier-transform (LTQ-FT) ion cyclotron resonance mass spectrometer, an instrument with high accuracy and resolution, is widely used in the identification and quantification of peptides and proteins. However, time-dependent errors in the system may lead to deterioration of the accuracy of these instruments, negatively influencing the determination of the mass error tolerance (MET) in database searches. Here, a comprehensive discussion of LTQ/FT precursor ion mass error is provided. On the basis of an investigation of the mass error distribution, we propose an improved recalibration formula and introduce a new tool, FTDR (Fourier-transform data recalibration), that employs a graphic user interface (GUI) for automatic calibration. It was found that the calibration could adjust the mass error distribution to more closely approximate a normal distribution and reduce the standard deviation (SD). Consequently, we present a new strategy, LDSF (Large MET database search and small MET filtration), for database search MET specification and validation of database search results. As the name implies, a large-MET database search is conducted and the search results are then filtered using the statistical MET estimated from high-confidence results. By applying this strategy to a standard protein data set and a complex data set, we demonstrate the LDSF can significantly improve the sensitivity of the result validation procedure.

Evaluation of Hand Written and Computerized Out-Patient Prescriptions in Urban Part of Central Gujarat.

PubMed

Joshi, Anuradha; Buch, Jatin; Kothari, Nitin; Shah, Nishal

2016-06-01

Prescription order is an important therapeutic transaction between physician and patient. A good quality prescription is an extremely important factor for minimizing errors in dispensing medication and it should be adherent to guidelines for prescription writing for benefit of the patient. To evaluate frequency and type of prescription errors in outpatient prescriptions and find whether prescription writing abides with WHO standards of prescription writing. A cross-sectional observational study was conducted at Anand city. Allopathic private practitioners practising at Anand city of different specialities were included in study. Collection of prescriptions was started a month after the consent to minimize bias in prescription writing. The prescriptions were collected from local pharmacy stores of Anand city over a period of six months. Prescriptions were analysed for errors in standard information, according to WHO guide to good prescribing. Descriptive analysis was performed to estimate frequency of errors, data were expressed as numbers and percentage. Total 749 (549 handwritten and 200 computerised) prescriptions were collected. Abundant omission errors were identified in handwritten prescriptions e.g., OPD number was mentioned in 6.19%, patient's age was mentioned in 25.50%, gender in 17.30%, address in 9.29% and weight of patient mentioned in 11.29%, while in drug items only 2.97% drugs were prescribed by generic name. Route and Dosage form was mentioned in 77.35%-78.15%, dose mentioned in 47.25%, unit in 13.91%, regimens were mentioned in 72.93% while signa (direction for drug use) in 62.35%. Total 4384 errors out of 549 handwritten prescriptions and 501 errors out of 200 computerized prescriptions were found in clinicians and patient details. While in drug item details, total number of errors identified were 5015 and 621 in handwritten and computerized prescriptions respectively. As compared to handwritten prescriptions, computerized prescriptions appeared to be associated with relatively lower rates of error. Since out-patient prescription errors are abundant and often occur in handwritten prescriptions, prescribers need to adapt themselves to computerized prescription order entry in their daily practice.

TU-H-207A-02: Relative Importance of the Various Factors Influencing the Accuracy of Monte Carlo Simulated CT Dose Index

DOE Office of Scientific and Technical Information (OSTI.GOV)

Marous, L; Muryn, J; Liptak, C

2016-06-15

Purpose: Monte Carlo simulation is a frequently used technique for assessing patient dose in CT. The accuracy of a Monte Carlo program is often validated using the standard CT dose index (CTDI) phantoms by comparing simulated and measured CTDI{sub 100}. To achieve good agreement, many input parameters in the simulation (e.g., energy spectrum and effective beam width) need to be determined. However, not all the parameters have equal importance. Our aim was to assess the relative importance of the various factors that influence the accuracy of simulated CTDI{sub 100}. Methods: A Monte Carlo program previously validated for a clinical CTmore » system was used to simulate CTDI{sub 100}. For the standard CTDI phantoms (32 and 16 cm in diameter), CTDI{sub 100} values from central and four peripheral locations at 70 and 120 kVp were first simulated using a set of reference input parameter values (treated as the truth). To emulate the situation in which the input parameter values used by the researcher may deviate from the truth, additional simulations were performed in which intentional errors were introduced into the input parameters, the effects of which on simulated CTDI{sub 100} were analyzed. Results: At 38.4-mm collimation, errors in effective beam width up to 5.0 mm showed negligible effects on simulated CTDI{sub 100} (<1.0%). Likewise, errors in acrylic density of up to 0.01 g/cm{sup 3} resulted in small CTDI{sub 100} errors (<2.5%). In contrast, errors in spectral HVL produced more significant effects: slight deviations (±0.2 mm Al) produced errors up to 4.4%, whereas more extreme deviations (±1.4 mm Al) produced errors as high as 25.9%. Lastly, ignoring the CT table introduced errors up to 13.9%. Conclusion: Monte Carlo simulated CTDI{sub 100} is insensitive to errors in effective beam width and acrylic density. However, they are sensitive to errors in spectral HVL. To obtain accurate results, the CT table should not be ignored. This work was supported by a Faculty Research and Development Award from Cleveland State University.« less

Evaluation of Hand Written and Computerized Out-Patient Prescriptions in Urban Part of Central Gujarat

PubMed Central

Buch, Jatin; Kothari, Nitin; Shah, Nishal

2016-01-01

Introduction Prescription order is an important therapeutic transaction between physician and patient. A good quality prescription is an extremely important factor for minimizing errors in dispensing medication and it should be adherent to guidelines for prescription writing for benefit of the patient. Aim To evaluate frequency and type of prescription errors in outpatient prescriptions and find whether prescription writing abides with WHO standards of prescription writing. Materials and Methods A cross-sectional observational study was conducted at Anand city. Allopathic private practitioners practising at Anand city of different specialities were included in study. Collection of prescriptions was started a month after the consent to minimize bias in prescription writing. The prescriptions were collected from local pharmacy stores of Anand city over a period of six months. Prescriptions were analysed for errors in standard information, according to WHO guide to good prescribing. Statistical Analysis Descriptive analysis was performed to estimate frequency of errors, data were expressed as numbers and percentage. Results Total 749 (549 handwritten and 200 computerised) prescriptions were collected. Abundant omission errors were identified in handwritten prescriptions e.g., OPD number was mentioned in 6.19%, patient’s age was mentioned in 25.50%, gender in 17.30%, address in 9.29% and weight of patient mentioned in 11.29%, while in drug items only 2.97% drugs were prescribed by generic name. Route and Dosage form was mentioned in 77.35%-78.15%, dose mentioned in 47.25%, unit in 13.91%, regimens were mentioned in 72.93% while signa (direction for drug use) in 62.35%. Total 4384 errors out of 549 handwritten prescriptions and 501 errors out of 200 computerized prescriptions were found in clinicians and patient details. While in drug item details, total number of errors identified were 5015 and 621 in handwritten and computerized prescriptions respectively. Conclusion As compared to handwritten prescriptions, computerized prescriptions appeared to be associated with relatively lower rates of error. Since out-patient prescription errors are abundant and often occur in handwritten prescriptions, prescribers need to adapt themselves to computerized prescription order entry in their daily practice. PMID:27504305

An analysis of four error detection and correction schemes for the proposed Federal standard 1024 (land mobile radio)

NASA Astrophysics Data System (ADS)

Lohrmann, Carol A.

1990-03-01

Interoperability of commercial Land Mobile Radios (LMR) and the military's tactical LMR is highly desirable if the U.S. government is to respond effectively in a national emergency or in a joint military operation. This ability to talk securely and immediately across agency and military service boundaries is often overlooked. One way to ensure interoperability is to develop and promote Federal communication standards (FS). This thesis surveys one area of the proposed FS 1024 for LMRs; namely, the error detection and correction (EDAC) of the message indicator (MI) bits used for cryptographic synchronization. Several EDAC codes are examined (Hamming, Quadratic Residue, hard decision Golay and soft decision Golay), tested on three FORTRAN programmed channel simulations (INMARSAT, Gaussian and constant burst width), compared and analyzed (based on bit error rates and percent of error-free super-frame runs) so that a best code can be recommended. Out of the four codes under study, the soft decision Golay code (24,12) is evaluated to be the best. This finding is based on the code's ability to detect and correct errors as well as the relative ease of implementation of the algorithm.

Top-of-Climb Matching Method for Reducing Aircraft Trajectory Prediction Errors.

PubMed

Thipphavong, David P

2016-09-01

The inaccuracies of the aircraft performance models utilized by trajectory predictors with regard to takeoff weight, thrust, climb profile, and other parameters result in altitude errors during the climb phase that often exceed the vertical separation standard of 1000 feet. This study investigates the potential reduction in altitude trajectory prediction errors that could be achieved for climbing flights if just one additional parameter is made available: top-of-climb (TOC) time. The TOC-matching method developed and evaluated in this paper is straightforward: a set of candidate trajectory predictions is generated using different aircraft weight parameters, and the one that most closely matches TOC in terms of time is selected. This algorithm was tested using more than 1000 climbing flights in Fort Worth Center. Compared to the baseline trajectory predictions of a real-time research prototype (Center/TRACON Automation System), the TOC-matching method reduced the altitude root mean square error (RMSE) for a 5-minute prediction time by 38%. It also decreased the percentage of flights with absolute altitude error greater than the vertical separation standard of 1000 ft for the same look-ahead time from 55% to 30%.

Local alignment of two-base encoded DNA sequence

PubMed Central

Homer, Nils; Merriman, Barry; Nelson, Stanley F

2009-01-01

Background DNA sequence comparison is based on optimal local alignment of two sequences using a similarity score. However, some new DNA sequencing technologies do not directly measure the base sequence, but rather an encoded form, such as the two-base encoding considered here. In order to compare such data to a reference sequence, the data must be decoded into sequence. The decoding is deterministic, but the possibility of measurement errors requires searching among all possible error modes and resulting alignments to achieve an optimal balance of fewer errors versus greater sequence similarity. Results We present an extension of the standard dynamic programming method for local alignment, which simultaneously decodes the data and performs the alignment, maximizing a similarity score based on a weighted combination of errors and edits, and allowing an affine gap penalty. We also present simulations that demonstrate the performance characteristics of our two base encoded alignment method and contrast those with standard DNA sequence alignment under the same conditions. Conclusion The new local alignment algorithm for two-base encoded data has substantial power to properly detect and correct measurement errors while identifying underlying sequence variants, and facilitating genome re-sequencing efforts based on this form of sequence data. PMID:19508732

Top-of-Climb Matching Method for Reducing Aircraft Trajectory Prediction Errors

PubMed Central

Thipphavong, David P.

2017-01-01

The inaccuracies of the aircraft performance models utilized by trajectory predictors with regard to takeoff weight, thrust, climb profile, and other parameters result in altitude errors during the climb phase that often exceed the vertical separation standard of 1000 feet. This study investigates the potential reduction in altitude trajectory prediction errors that could be achieved for climbing flights if just one additional parameter is made available: top-of-climb (TOC) time. The TOC-matching method developed and evaluated in this paper is straightforward: a set of candidate trajectory predictions is generated using different aircraft weight parameters, and the one that most closely matches TOC in terms of time is selected. This algorithm was tested using more than 1000 climbing flights in Fort Worth Center. Compared to the baseline trajectory predictions of a real-time research prototype (Center/TRACON Automation System), the TOC-matching method reduced the altitude root mean square error (RMSE) for a 5-minute prediction time by 38%. It also decreased the percentage of flights with absolute altitude error greater than the vertical separation standard of 1000 ft for the same look-ahead time from 55% to 30%. PMID:28684883

Top-of-Climb Matching Method for Reducing Aircraft Trajectory Prediction Errors

NASA Technical Reports Server (NTRS)

Thipphavong, David P.

2016-01-01

The inaccuracies of the aircraft performance models utilized by trajectory predictors with regard to takeoff weight, thrust, climb profile, and other parameters result in altitude errors during the climb phase that often exceed the vertical separation standard of 1000 feet. This study investigates the potential reduction in altitude trajectory prediction errors that could be achieved for climbing flights if just one additional parameter is made available: top-of-climb (TOC) time. The TOC-matching method developed and evaluated in this paper is straightforward: a set of candidate trajectory predictions is generated using different aircraft weight parameters, and the one that most closely matches TOC in terms of time is selected. This algorithm was tested using more than 1000 climbing flights in Fort Worth Center. Compared to the baseline trajectory predictions of a real-time research prototype (Center/TRACON Automation System), the TOC-matching method reduced the altitude root mean square error (RMSE) for a 5-minute prediction time by 38%. It also decreased the percentage of flights with absolute altitude error greater than the vertical separation standard of 1000 ft for the same look-ahead time from 55% to 30%.

Adjustment of regional regression models of urban-runoff quality using data for Chattanooga, Knoxville, and Nashville, Tennessee

USGS Publications Warehouse

Hoos, Anne B.; Patel, Anant R.

1996-01-01

Model-adjustment procedures were applied to the combined data bases of storm-runoff quality for Chattanooga, Knoxville, and Nashville, Tennessee, to improve predictive accuracy for storm-runoff quality for urban watersheds in these three cities and throughout Middle and East Tennessee. Data for 45 storms at 15 different sites (five sites in each city) constitute the data base. Comparison of observed values of storm-runoff load and event-mean concentration to the predicted values from the regional regression models for 10 constituents shows prediction errors, as large as 806,000 percent. Model-adjustment procedures, which combine the regional model predictions with local data, are applied to improve predictive accuracy. Standard error of estimate after model adjustment ranges from 67 to 322 percent. Calibration results may be biased due to sampling error in the Tennessee data base. The relatively large values of standard error of estimate for some of the constituent models, although representing significant reduction (at least 50 percent) in prediction error compared to estimation with unadjusted regional models, may be unacceptable for some applications. The user may wish to collect additional local data for these constituents and repeat the analysis, or calibrate an independent local regression model.

Assessment of a model for achieving competency in administration and scoring of the WAIS-IV in post-graduate psychology students.

PubMed

Roberts, Rachel M; Davis, Melissa C

2015-01-01

There is a need for an evidence-based approach to training professional psychologists in the administration and scoring of standardized tests such as the Wechsler Adult Intelligence Scale (WAIS) due to substantial evidence that these tasks are associated with numerous errors that have the potential to significantly impact clients' lives. Twenty three post-graduate psychology students underwent training in using the WAIS-IV according to a best-practice teaching model that involved didactic teaching, independent study of the test manual, and in-class practice with teacher supervision and feedback. Video recordings and test protocols from a role-played test administration were analyzed for errors according to a comprehensive checklist with self, peer, and faculty member reviews. 91.3% of students were rated as having demonstrated competency in administration and scoring. All students were found to make errors, with substantially more errors being detected by the faculty member than by self or peers. Across all subtests, the most frequent errors related to failure to deliver standardized instructions verbatim from the manual. The failure of peer and self-reviews to detect the majority of the errors suggests that novice feedback (self or peers) may be ineffective to eliminate errors and the use of more senior peers may be preferable. It is suggested that involving senior trainees, recent graduates and/or experienced practitioners in the training of post-graduate students may have benefits for both parties, promoting a peer-learning and continuous professional development approach to the development and maintenance of skills in psychological assessment.

The performance of the standard rate turn (SRT) by student naval helicopter pilots.

PubMed

Chapman, F; Temme, L A; Still, D L

2001-04-01

During flight training, student naval helicopter pilots learn the use of flight instruments through a prescribed series of simulator training events. The training simulator is a 6-degrees-of-freedom, motion-based, high-fidelity instrument trainer. From the final basic instrument simulator flights of student pilots, we selected for evaluation and analysis their performance of the Standard Rate Turn (SRT), a routine flight maneuver. The performance of the SRT was scored with air speed, altitude and heading average error from target values and standard deviations. These average errors and standard deviations were used in a Multiple Analysis of Variance (MANOVA) to evaluate the effects of three independent variables: 1) direction of turn (left vs. right), 2) degree of turn (180 vs. 360 degrees); and 3) segment of turn (roll-in, first 30 s, last 30 s, and roll-out of turn). Only the main effects of the three independent variables were significant; there were no significant interactions. This result greatly reduces the number of different conditions that should be scored separately for the evaluation of SRT performance. The results also showed that the magnitude of the heading and altitude errors at the beginning of the SRT correlated with the magnitude of the heading and altitude errors throughout the turn. This result suggests that for the turn to be well executed, it is important for it to begin with little error in these two response parameters. The observations reported here should be considered when establishing SRT performance norms and comparing student scores. Furthermore, it seems easier for pilots to maintain good performance than to correct poor performance.

Cost effectiveness of the U.S. Geological Survey's stream-gaging program in Wisconsin

USGS Publications Warehouse

Walker, J.F.; Osen, L.L.; Hughes, P.E.

1987-01-01

A minimum budget of $510,000 is required to operate the program; a budget less than this does not permit proper service and maintenance of the gaging stations. At this minimum budget, the theoretical average standard error of instantaneous discharge is 14.4%. The maximum budget analyzed was $650,000 and resulted in an average standard of error of instantaneous discharge of 7.2%. 

How Much Confidence Can We Have in EU-SILC? Complex Sample Designs and the Standard Error of the Europe 2020 Poverty Indicators

ERIC Educational Resources Information Center

Goedeme, Tim

2013-01-01

If estimates are based on samples, they should be accompanied by appropriate standard errors and confidence intervals. This is true for scientific research in general, and is even more important if estimates are used to inform and evaluate policy measures such as those aimed at attaining the Europe 2020 poverty reduction target. In this article I…

Comparison of Optimal Design Methods in Inverse Problems

PubMed Central

Banks, H. T.; Holm, Kathleen; Kappel, Franz

2011-01-01

Typical optimal design methods for inverse or parameter estimation problems are designed to choose optimal sampling distributions through minimization of a specific cost function related to the resulting error in parameter estimates. It is hoped that the inverse problem will produce parameter estimates with increased accuracy using data collected according to the optimal sampling distribution. Here we formulate the classical optimal design problem in the context of general optimization problems over distributions of sampling times. We present a new Prohorov metric based theoretical framework that permits one to treat succinctly and rigorously any optimal design criteria based on the Fisher Information Matrix (FIM). A fundamental approximation theory is also included in this framework. A new optimal design, SE-optimal design (standard error optimal design), is then introduced in the context of this framework. We compare this new design criteria with the more traditional D-optimal and E-optimal designs. The optimal sampling distributions from each design are used to compute and compare standard errors; the standard errors for parameters are computed using asymptotic theory or bootstrapping and the optimal mesh. We use three examples to illustrate ideas: the Verhulst-Pearl logistic population model [13], the standard harmonic oscillator model [13] and a popular glucose regulation model [16, 19, 29]. PMID:21857762

Enhanced Oceanic Operations Human-In-The-Loop In-Trail Procedure Validation Simulation Study

NASA Technical Reports Server (NTRS)

Murdoch, Jennifer L.; Bussink, Frank J. L.; Chamberlain, James P.; Chartrand, Ryan C.; Palmer, Michael T.; Palmer, Susan O.

2008-01-01

The Enhanced Oceanic Operations Human-In-The-Loop In-Trail Procedure (ITP) Validation Simulation Study investigated the viability of an ITP designed to enable oceanic flight level changes that would not otherwise be possible. Twelve commercial airline pilots with current oceanic experience flew a series of simulated scenarios involving either standard or ITP flight level change maneuvers and provided subjective workload ratings, assessments of ITP validity and acceptability, and objective performance measures associated with the appropriate selection, request, and execution of ITP flight level change maneuvers. In the majority of scenarios, subject pilots correctly assessed the traffic situation, selected an appropriate response (i.e., either a standard flight level change request, an ITP request, or no request), and executed their selected flight level change procedure, if any, without error. Workload ratings for ITP maneuvers were acceptable and not substantially higher than for standard flight level change maneuvers, and, for the majority of scenarios and subject pilots, subjective acceptability ratings and comments for ITP were generally high and positive. Qualitatively, the ITP was found to be valid and acceptable. However, the error rates for ITP maneuvers were higher than for standard flight level changes, and these errors may have design implications for both the ITP and the study's prototype traffic display. These errors and their implications are discussed.

Cost-effectiveness of the stream-gaging program in North Carolina

USGS Publications Warehouse

Mason, R.R.; Jackson, N.M.

1985-01-01

This report documents the results of a study of the cost-effectiveness of the stream-gaging program in North Carolina. Data uses and funding sources are identified for the 146 gaging stations currently operated in North Carolina with a budget of $777,600 (1984). As a result of the study, eleven stations are nominated for discontinuance and five for conversion from recording to partial-record status. Large parts of North Carolina 's Coastal Plain are identified as having sparse streamflow data. This sparsity should be remedied as funds become available. Efforts should also be directed toward defining the efforts of drainage improvements on local hydrology and streamflow characteristics. The average standard error of streamflow records in North Carolina is 18.6 percent. This level of accuracy could be improved without increasing cost by increasing the frequency of field visits and streamflow measurements at stations with high standard errors and reducing the frequency at stations with low standard errors. A minimum budget of $762,000 is required to operate the 146-gage program. A budget less than this does not permit proper service and maintenance of the gages and recorders. At the minimum budget, and with the optimum allocation of field visits, the average standard error is 17.6 percent.

The performance of projective standardization for digital subtraction radiography.

PubMed

Mol, André; Dunn, Stanley M

2003-09-01

We sought to test the performance and robustness of projective standardization in preserving invariant properties of subtraction images in the presence of irreversible projection errors. Study design Twenty bone chips (1-10 mg each) were placed on dentate dry mandibles. Follow-up images were obtained without the bone chips, and irreversible projection errors of up to 6 degrees were introduced. Digitized image intensities were normalized, and follow-up images were geometrically reconstructed by 2 operators using anatomical and fiduciary landmarks. Subtraction images were analyzed by 3 observers. Regression analysis revealed a linear relationship between radiographic estimates of mineral loss and actual mineral loss (R(2) = 0.99; P <.05). The effect of projection error was not significant (general linear model [GLM]: P >.05). There was no difference between the radiographic estimates from images standardized with anatomical landmarks and those standardized with fiduciary landmarks (Wilcoxon signed rank test: P >.05). Operator variability was low for image analysis alone (R(2) = 0.99; P <.05), as well as for the entire procedure (R(2) = 0.98; P <.05). The predicted detection limit was smaller than 1 mg. Subtraction images registered by projective standardization yield estimates of osseous change that are invariant to irreversible projection errors of up to 6 degrees. Within these limits, operator precision is high and anatomical landmarks can be used to establish correspondence.

A new method for the assessment of patient safety competencies during a medical school clerkship using an objective structured clinical examination

PubMed Central

Daud-Gallotti, Renata Mahfuz; Morinaga, Christian Valle; Arlindo-Rodrigues, Marcelo; Velasco, Irineu Tadeu; Arruda Martins, Milton; Tiberio, Iolanda Calvo

2011-01-01

INTRODUCTION: Patient safety is seldom assessed using objective evaluations during undergraduate medical education. OBJECTIVE: To evaluate the performance of fifth-year medical students using an objective structured clinical examination focused on patient safety after implementation of an interactive program based on adverse events recognition and disclosure. METHODS: In 2007, a patient safety program was implemented in the internal medicine clerkship of our hospital. The program focused on human error theory, epidemiology of incidents, adverse events, and disclosure. Upon completion of the program, students completed an objective structured clinical examination with five stations and standardized patients. One station focused on patient safety issues, including medical error recognition/disclosure, the patient-physician relationship and humanism issues. A standardized checklist was completed by each standardized patient to assess the performance of each student. The student's global performance at each station and performance in the domains of medical error, the patient-physician relationship and humanism were determined. The correlations between the student performances in these three domains were calculated. RESULTS: A total of 95 students participated in the objective structured clinical examination. The mean global score at the patient safety station was 87.59±1.24 points. Students' performance in the medical error domain was significantly lower than their performance on patient-physician relationship and humanistic issues. Less than 60% of students (n = 54) offered the simulated patient an apology after a medical error occurred. A significant correlation was found between scores obtained in the medical error domains and scores related to both the patient-physician relationship and humanistic domains. CONCLUSIONS: An objective structured clinical examination is a useful tool to evaluate patient safety competencies during the medical student clerkship. PMID:21876976

An Algorithm for Retrieving Land Surface Temperatures Using VIIRS Data in Combination with Multi-Sensors

PubMed Central

Xia, Lang; Mao, Kebiao; Ma, Ying; Zhao, Fen; Jiang, Lipeng; Shen, Xinyi; Qin, Zhihao

2014-01-01

A practical algorithm was proposed to retrieve land surface temperature (LST) from Visible Infrared Imager Radiometer Suite (VIIRS) data in mid-latitude regions. The key parameter transmittance is generally computed from water vapor content, while water vapor channel is absent in VIIRS data. In order to overcome this shortcoming, the water vapor content was obtained from Moderate Resolution Imaging Spectroradiometer (MODIS) data in this study. The analyses on the estimation errors of vapor content and emissivity indicate that when the water vapor errors are within the range of ±0.5 g/cm2, the mean retrieval error of the present algorithm is 0.634 K; while the land surface emissivity errors range from −0.005 to +0.005, the mean retrieval error is less than 1.0 K. Validation with the standard atmospheric simulation shows the average LST retrieval error for the twenty-three land types is 0.734 K, with a standard deviation value of 0.575 K. The comparison between the ground station LST data indicates the retrieval mean accuracy is −0.395 K, and the standard deviation value is 1.490 K in the regions with vegetation and water cover. Besides, the retrieval results of the test data have also been compared with the results measured by the National Oceanic and Atmospheric Administration (NOAA) VIIRS LST products, and the results indicate that 82.63% of the difference values are within the range of −1 to 1 K, and 17.37% of the difference values are within the range of ±2 to ±1 K. In a conclusion, with the advantages of multi-sensors taken fully exploited, more accurate results can be achieved in the retrieval of land surface temperature. PMID:25397919

Error coding simulations in C

NASA Technical Reports Server (NTRS)

Noble, Viveca K.

1994-01-01

When data is transmitted through a noisy channel, errors are produced within the data rendering it indecipherable. Through the use of error control coding techniques, the bit error rate can be reduced to any desired level without sacrificing the transmission data rate. The Astrionics Laboratory at Marshall Space Flight Center has decided to use a modular, end-to-end telemetry data simulator to simulate the transmission of data from flight to ground and various methods of error control. The simulator includes modules for random data generation, data compression, Consultative Committee for Space Data Systems (CCSDS) transfer frame formation, error correction/detection, error generation and error statistics. The simulator utilizes a concatenated coding scheme which includes CCSDS standard (255,223) Reed-Solomon (RS) code over GF(2(exp 8)) with interleave depth of 5 as the outermost code, (7, 1/2) convolutional code as an inner code and CCSDS recommended (n, n-16) cyclic redundancy check (CRC) code as the innermost code, where n is the number of information bits plus 16 parity bits. The received signal-to-noise for a desired bit error rate is greatly reduced through the use of forward error correction techniques. Even greater coding gain is provided through the use of a concatenated coding scheme. Interleaving/deinterleaving is necessary to randomize burst errors which may appear at the input of the RS decoder. The burst correction capability length is increased in proportion to the interleave depth. The modular nature of the simulator allows for inclusion or exclusion of modules as needed. This paper describes the development and operation of the simulator, the verification of a C-language Reed-Solomon code, and the possibility of using Comdisco SPW(tm) as a tool for determining optimal error control schemes.

The intention to disclose medical errors among doctors in a referral hospital in North Malaysia.

PubMed

Hs, Arvinder-Singh; Rashid, Abdul

2017-01-23

In this study, medical errors are defined as unintentional patient harm caused by a doctor's mistake. This topic, due to limited research, is poorly understood in Malaysia. The objective of this study was to determine the proportion of doctors intending to disclose medical errors, and their attitudes/perception pertaining to medical errors. This cross-sectional study was conducted at a tertiary public hospital from July- December 2015 among 276 randomly selected doctors. Data was collected using a standardized and validated self-administered questionnaire intending to measure disclosure and attitudes/perceptions. The scale had four vignettes in total two medical and two surgical. Each vignette consisted of five questions and each question measured the disclosure. Disclosure was categorised as "No Disclosure", "Partial Disclosure" or "Full Disclosure". Data was keyed in and analysed using STATA v 13.0. Only 10.1% (n = 28) intended to disclose medical errors. Most respondents felt that they possessed an attitude/perception of adequately disclosing errors to patients. There was a statistically significant difference (p < 0.001) when comparing the intention of disclosure with perceived disclosures. Most respondents were in common agreement that disclosing an error would make them less likely to get sued, that minor errors should be reported and that they experienced relief from disclosing errors. Most doctors in this study would not disclose medical errors although they perceived that the errors were serious and felt responsible for it. Poor disclosure could be due the fear of litigations and improper mechanisms/procedures available for disclosure.

Errors in clinical laboratories or errors in laboratory medicine?

PubMed

Plebani, Mario

2006-01-01

Laboratory testing is a highly complex process and, although laboratory services are relatively safe, they are not as safe as they could or should be. Clinical laboratories have long focused their attention on quality control methods and quality assessment programs dealing with analytical aspects of testing. However, a growing body of evidence accumulated in recent decades demonstrates that quality in clinical laboratories cannot be assured by merely focusing on purely analytical aspects. The more recent surveys on errors in laboratory medicine conclude that in the delivery of laboratory testing, mistakes occur more frequently before (pre-analytical) and after (post-analytical) the test has been performed. Most errors are due to pre-analytical factors (46-68.2% of total errors), while a high error rate (18.5-47% of total errors) has also been found in the post-analytical phase. Errors due to analytical problems have been significantly reduced over time, but there is evidence that, particularly for immunoassays, interference may have a serious impact on patients. A description of the most frequent and risky pre-, intra- and post-analytical errors and advice on practical steps for measuring and reducing the risk of errors is therefore given in the present paper. Many mistakes in the Total Testing Process are called "laboratory errors", although these may be due to poor communication, action taken by others involved in the testing process (e.g., physicians, nurses and phlebotomists), or poorly designed processes, all of which are beyond the laboratory's control. Likewise, there is evidence that laboratory information is only partially utilized. A recent document from the International Organization for Standardization (ISO) recommends a new, broader definition of the term "laboratory error" and a classification of errors according to different criteria. In a modern approach to total quality, centered on patients' needs and satisfaction, the risk of errors and mistakes in pre- and post-examination steps must be minimized to guarantee the total quality of laboratory services.

SU-F-T-471: Simulated External Beam Delivery Errors Detection with a Large Area Ion Chamber Transmission Detector

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hoffman, D; Dyer, B; Kumaran Nair, C

Purpose: The Integral Quality Monitor (IQM), developed by iRT Systems GmbH (Koblenz, Germany) is a large-area, linac-mounted ion chamber used to monitor photon fluence during patient treatment. Our previous work evaluated the change of the ion chamber’s response to deviations from static 1×1 cm2 and 10×10 cm2 photon beams and other characteristics integral to use in external beam detection. The aim of this work is to simulate two external beam radiation delivery errors, quantify the detection of simulated errors and evaluate the reduction in patient harm resulting from detection. Methods: Two well documented radiation oncology delivery errors were selected formore » simulation. The first error was recreated by modifying a wedged whole breast treatment, removing the physical wedge and calculating the planned dose with Pinnacle TPS (Philips Radiation Oncology Systems, Fitchburg, WI). The second error was recreated by modifying a static-gantry IMRT pharyngeal tonsil plan to be delivered in 3 unmodulated fractions. A radiation oncologist evaluated the dose for simulated errors and predicted morbidity and mortality commiserate with the original reported toxicity, indicating that reported errors were approximately simulated. The ion chamber signal of unmodified treatments was compared to the simulated error signal and evaluated in Pinnacle TPS again with radiation oncologist prediction of simulated patient harm. Results: Previous work established that transmission detector system measurements are stable within 0.5% standard deviation (SD). Errors causing signal change greater than 20 SD (10%) were considered detected. The whole breast and pharyngeal tonsil IMRT simulated error increased signal by 215% and 969%, respectively, indicating error detection after the first fraction and IMRT segment, respectively. Conclusion: The transmission detector system demonstrated utility in detecting clinically significant errors and reducing patient toxicity/harm in simulated external beam delivery. Future work will evaluate detection of other smaller magnitude delivery errors.« less

SU-E-T-789: Validation of 3DVH Accuracy On Quantifying Delivery Errors Based On Clinical Relevant DVH Metrics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ma, T; Kumaraswamy, L

Purpose: Detection of treatment delivery errors is important in radiation therapy. However, accurate quantification of delivery errors is also of great importance. This study aims to evaluate the 3DVH software’s ability to accurately quantify delivery errors. Methods: Three VMAT plans (prostate, H&N and brain) were randomly chosen for this study. First, we evaluated whether delivery errors could be detected by gamma evaluation. Conventional per-beam IMRT QA was performed with the ArcCHECK diode detector for the original plans and for the following modified plans: (1) induced dose difference error up to ±4.0% and (2) control point (CP) deletion (3 to 10more » CPs were deleted) (3) gantry angle shift error (3 degree uniformly shift). 2D and 3D gamma evaluation were performed for all plans through SNC Patient and 3DVH, respectively. Subsequently, we investigated the accuracy of 3DVH analysis for all cases. This part evaluated, using the Eclipse TPS plans as standard, whether 3DVH accurately can model the changes in clinically relevant metrics caused by the delivery errors. Results: 2D evaluation seemed to be more sensitive to delivery errors. The average differences between ECLIPSE predicted and 3DVH results for each pair of specific DVH constraints were within 2% for all three types of error-induced treatment plans, illustrating the fact that 3DVH is fairly accurate in quantifying the delivery errors. Another interesting observation was that even though the gamma pass rates for the error plans are high, the DVHs showed significant differences between original plan and error-induced plans in both Eclipse and 3DVH analysis. Conclusion: The 3DVH software is shown to accurately quantify the error in delivered dose based on clinically relevant DVH metrics, where a conventional gamma based pre-treatment QA might not necessarily detect.« less

Detection and avoidance of errors in computer software

NASA Technical Reports Server (NTRS)

Kinsler, Les

1989-01-01

The acceptance test errors of a computer software project to determine if the errors could be detected or avoided in earlier phases of development. GROAGSS (Gamma Ray Observatory Attitude Ground Support System) was selected as the software project to be examined. The development of the software followed the standard Flight Dynamics Software Development methods. GROAGSS was developed between August 1985 and April 1989. The project is approximately 250,000 lines of code of which approximately 43,000 lines are reused from previous projects. GROAGSS had a total of 1715 Change Report Forms (CRFs) submitted during the entire development and testing. These changes contained 936 errors. Of these 936 errors, 374 were found during the acceptance testing. These acceptance test errors were first categorized into methods of avoidance including: more clearly written requirements; detail review; code reading; structural unit testing; and functional system integration testing. The errors were later broken down in terms of effort to detect and correct, class of error, and probability that the prescribed detection method would be successful. These determinations were based on Software Engineering Laboratory (SEL) documents and interviews with the project programmers. A summary of the results of the categorizations is presented. The number of programming errors at the beginning of acceptance testing can be significantly reduced. The results of the existing development methodology are examined for ways of improvements. A basis is provided for the definition is a new development/testing paradigm. Monitoring of the new scheme will objectively determine its effectiveness on avoiding and detecting errors.

Reliable Channel-Adapted Error Correction: Bacon-Shor Code Recovery from Amplitude Damping

NASA Astrophysics Data System (ADS)

Piedrafita, Álvaro; Renes, Joseph M.

2017-12-01

We construct two simple error correction schemes adapted to amplitude damping noise for Bacon-Shor codes and investigate their prospects for fault-tolerant implementation. Both consist solely of Clifford gates and require far fewer qubits, relative to the standard method, to achieve exact correction to a desired order in the damping rate. The first, employing one-bit teleportation and single-qubit measurements, needs only one-fourth as many physical qubits, while the second, using just stabilizer measurements and Pauli corrections, needs only half. The improvements stem from the fact that damping events need only be detected, not corrected, and that effective phase errors arising due to undamped qubits occur at a lower rate than damping errors. For error correction that is itself subject to damping noise, we show that existing fault-tolerance methods can be employed for the latter scheme, while the former can be made to avoid potential catastrophic errors and can easily cope with damping faults in ancilla qubits.

Math Error Types and Correlates in Adolescents with and without Attention Deficit Hyperactivity Disorder

PubMed Central

Capodieci, Agnese; Martinussen, Rhonda

2017-01-01

Objective: The aim of this study was to examine the types of errors made by youth with and without a parent-reported diagnosis of attention deficit and hyperactivity disorder (ADHD) on a math fluency task and investigate the association between error types and youths’ performance on measures of processing speed and working memory. Method: Participants included 30 adolescents with ADHD and 39 typically developing peers between 14 and 17 years old matched in age and IQ. All youth completed standardized measures of math calculation and fluency as well as two tests of working memory and processing speed. Math fluency error patterns were examined. Results: Adolescents with ADHD showed less proficient math fluency despite having similar math calculation scores as their peers. Group differences were also observed in error types with youth with ADHD making more switch errors than their peers. Conclusion: This research has important clinical applications for the assessment and intervention on math ability in students with ADHD. PMID:29075227

Math Error Types and Correlates in Adolescents with and without Attention Deficit Hyperactivity Disorder.

PubMed

Capodieci, Agnese; Martinussen, Rhonda

2017-01-01

Objective: The aim of this study was to examine the types of errors made by youth with and without a parent-reported diagnosis of attention deficit and hyperactivity disorder (ADHD) on a math fluency task and investigate the association between error types and youths' performance on measures of processing speed and working memory. Method: Participants included 30 adolescents with ADHD and 39 typically developing peers between 14 and 17 years old matched in age and IQ. All youth completed standardized measures of math calculation and fluency as well as two tests of working memory and processing speed. Math fluency error patterns were examined. Results: Adolescents with ADHD showed less proficient math fluency despite having similar math calculation scores as their peers. Group differences were also observed in error types with youth with ADHD making more switch errors than their peers. Conclusion: This research has important clinical applications for the assessment and intervention on math ability in students with ADHD.

Attention failures versus misplaced diligence: separating attention lapses from speed-accuracy trade-offs.

PubMed

Seli, Paul; Cheyne, James Allan; Smilek, Daniel

2012-03-01

In two studies of a GO-NOGO task assessing sustained attention, we examined the effects of (1) altering speed-accuracy trade-offs through instructions (emphasizing both speed and accuracy or accuracy only) and (2) auditory alerts distributed throughout the task. Instructions emphasizing accuracy reduced errors and changed the distribution of GO trial RTs. Additionally, correlations between errors and increasing RTs produced a U-function; excessively fast and slow RTs accounted for much of the variance of errors. Contrary to previous reports, alerts increased errors and RT variability. The results suggest that (1) standard instructions for sustained attention tasks, emphasizing speed and accuracy equally, produce errors arising from attempts to conform to the misleading requirement for speed, which become conflated with attention-lapse produced errors and (2) auditory alerts have complex, and sometimes deleterious, effects on attention. We argue that instructions emphasizing accuracy provide a more precise assessment of attention lapses in sustained attention tasks. Copyright © 2011 Elsevier Inc. All rights reserved.

Error-tradeoff and error-disturbance relations for incompatible quantum measurements.

PubMed

Branciard, Cyril

2013-04-23

Heisenberg's uncertainty principle is one of the main tenets of quantum theory. Nevertheless, and despite its fundamental importance for our understanding of quantum foundations, there has been some confusion in its interpretation: Although Heisenberg's first argument was that the measurement of one observable on a quantum state necessarily disturbs another incompatible observable, standard uncertainty relations typically bound the indeterminacy of the outcomes when either one or the other observable is measured. In this paper, we quantify precisely Heisenberg's intuition. Even if two incompatible observables cannot be measured together, one can still approximate their joint measurement, at the price of introducing some errors with respect to the ideal measurement of each of them. We present a tight relation characterizing the optimal tradeoff between the error on one observable vs. the error on the other. As a particular case, our approach allows us to characterize the disturbance of an observable induced by the approximate measurement of another one; we also derive a stronger error-disturbance relation for this scenario.

Partnerships With Aviation: Promoting a Culture of Safety in Health Care.

PubMed

Skinner, Lori; Tripp, Terrance R; Scouler, David; Pechacek, Judith M

2015-01-01

According to the Institute of Medicine (IOM, 1999, p. 1), "Medical errors can be defined as the failure of a planned action to be completed as intended or the use of a wrong plan to achieve an aim." The current health care culture is disjointed, as evidenced by a lack of consistent reporting standards for all providers; provider licensing pays little attention to errors, and there are no financial incentives to improve safety (IOM, 1999). Many errors in health care are preventable. "Near misses" and adverse events that do occur can offer insight on how to improve practice and prevent future events. The aim of this article is to better understand underreporting of errors in health care, to present a model of change that increases voluntary error reporting, and to discuss the role nurse executives play in creating a culture of safety. This article explores how high reliability organizations such as aviation improve safety through enhanced error reporting, culture change, and teamwork.

Database Design to Ensure Anonymous Study of Medical Errors: A Report from the ASIPS collaborative

PubMed Central

Pace, Wilson D.; Staton, Elizabeth W.; Higgins, Gregory S.; Main, Deborah S.; West, David R.; Harris, Daniel M.

2003-01-01

Medical error reporting systems are important information sources for designing strategies to improve the safety of health care. Applied Strategies for Improving Patient Safety (ASIPS) is a multi-institutional, practice-based research project that collects and analyzes data on primary care medical errors and develops interventions to reduce error. The voluntary ASIPS Patient Safety Reporting System captures anonymous and confidential reports of medical errors. Confidential reports, which are quickly de-identified, provide better detail than do anonymous reports; however, concerns exist about the confidentiality of those reports should the database be subject to legal discovery or other security breaches. Standard database elements, for example, serial ID numbers, date/time stamps, and backups, could enable an outsider to link an ASIPS report to a specific medical error. The authors present the design and implementation of a database and administrative system that reduce this risk, facilitate research, and maintain near anonymity of the events, practices, and clinicians. PMID:12925548

Sensitivity of the model error parameter specification in weak-constraint four-dimensional variational data assimilation

NASA Astrophysics Data System (ADS)

Shaw, Jeremy A.; Daescu, Dacian N.

2017-08-01

This article presents the mathematical framework to evaluate the sensitivity of a forecast error aspect to the input parameters of a weak-constraint four-dimensional variational data assimilation system (w4D-Var DAS), extending the established theory from strong-constraint 4D-Var. Emphasis is placed on the derivation of the equations for evaluating the forecast sensitivity to parameters in the DAS representation of the model error statistics, including bias, standard deviation, and correlation structure. A novel adjoint-based procedure for adaptive tuning of the specified model error covariance matrix is introduced. Results from numerical convergence tests establish the validity of the model error sensitivity equations. Preliminary experiments providing a proof-of-concept are performed using the Lorenz multi-scale model to illustrate the theoretical concepts and potential benefits for practical applications.

Average symbol error rate for M-ary quadrature amplitude modulation in generalized atmospheric turbulence and misalignment errors

NASA Astrophysics Data System (ADS)

Sharma, Prabhat Kumar

2016-11-01

A framework is presented for the analysis of average symbol error rate (SER) for M-ary quadrature amplitude modulation in a free-space optical communication system. The standard probability density function (PDF)-based approach is extended to evaluate the average SER by representing the Q-function through its Meijer's G-function equivalent. Specifically, a converging power series expression for the average SER is derived considering the zero-boresight misalignment errors in the receiver side. The analysis presented here assumes a unified expression for the PDF of channel coefficient which incorporates the M-distributed atmospheric turbulence and Rayleigh-distributed radial displacement for the misalignment errors. The analytical results are compared with the results obtained using Q-function approximation. Further, the presented results are supported by the Monte Carlo simulations.

Noise-induced errors in geophysical parameter estimation from retarding potential analyzers in low Earth orbit

NASA Astrophysics Data System (ADS)

Debchoudhury, Shantanab; Earle, Gregory

2017-04-01

Retarding Potential Analyzers (RPA) have a rich flight heritage. Standard curve-fitting analysis techniques exist that can infer state variables in the ionospheric plasma environment from RPA data, but the estimation process is prone to errors arising from a number of sources. Previous work has focused on the effects of grid geometry on uncertainties in estimation; however, no prior study has quantified the estimation errors due to additive noise. In this study, we characterize the errors in estimation of thermal plasma parameters by adding noise to the simulated data derived from the existing ionospheric models. We concentrate on low-altitude, mid-inclination orbits since a number of nano-satellite missions are focused on this region of the ionosphere. The errors are quantified and cross-correlated for varying geomagnetic conditions.

Investigation of writing error in staggered heated-dot magnetic recording systems

NASA Astrophysics Data System (ADS)

Tipcharoen, W.; Warisarn, C.; Tongsomporn, D.; Karns, D.; Kovintavewat, P.

2017-05-01

To achieve an ultra-high storage capacity, heated-dot magnetic recording (HDMR) has been proposed, which heats a bit-patterned medium before recording data. Generally, an error during the HDMR writing process comes from several sources; however, we only investigate the effects of staggered island arrangement, island size fluctuation caused by imperfect fabrication, and main pole position fluctuation. Simulation results demonstrate that a writing error can be minimized by using a staggered array (hexagonal lattice) instead of a square array. Under the effect of main pole position fluctuation, the writing error is higher than the system without main pole position fluctuation. Finally, we found that the error percentage can drop below 10% when the island size is 8.5 nm and the standard deviation of the island size is 1 nm in the absence of main pole jitter.

Discrete distributed strain sensing of intelligent structures

NASA Technical Reports Server (NTRS)

Anderson, Mark S.; Crawley, Edward F.

1992-01-01

Techniques are developed for the design of discrete highly distributed sensor systems for use in intelligent structures. First the functional requirements for such a system are presented. Discrete spatially averaging strain sensors are then identified as satisfying the functional requirements. A variety of spatial weightings for spatially averaging sensors are examined, and their wave number characteristics are determined. Preferable spatial weightings are identified. Several numerical integration rules used to integrate such sensors in order to determine the global deflection of the structure are discussed. A numerical simulation is conducted using point and rectangular sensors mounted on a cantilevered beam under static loading. Gage factor and sensor position uncertainties are incorporated to assess the absolute error and standard deviation of the error in the estimated tip displacement found by numerically integrating the sensor outputs. An experiment is carried out using a statically loaded cantilevered beam with five point sensors. It is found that in most cases the actual experimental error is within one standard deviation of the absolute error as found in the numerical simulation.

Human Error Analysis in a Permit to Work System: A Case Study in a Chemical Plant

PubMed Central

Jahangiri, Mehdi; Hoboubi, Naser; Rostamabadi, Akbar; Keshavarzi, Sareh; Hosseini, Ali Akbar

2015-01-01

Background A permit to work (PTW) is a formal written system to control certain types of work which are identified as potentially hazardous. However, human error in PTW processes can lead to an accident. Methods This cross-sectional, descriptive study was conducted to estimate the probability of human errors in PTW processes in a chemical plant in Iran. In the first stage, through interviewing the personnel and studying the procedure in the plant, the PTW process was analyzed using the hierarchical task analysis technique. In doing so, PTW was considered as a goal and detailed tasks to achieve the goal were analyzed. In the next step, the standardized plant analysis risk-human (SPAR-H) reliability analysis method was applied for estimation of human error probability. Results The mean probability of human error in the PTW system was estimated to be 0.11. The highest probability of human error in the PTW process was related to flammable gas testing (50.7%). Conclusion The SPAR-H method applied in this study could analyze and quantify the potential human errors and extract the required measures for reducing the error probabilities in PTW system. Some suggestions to reduce the likelihood of errors, especially in the field of modifying the performance shaping factors and dependencies among tasks are provided. PMID:27014485

DOE Office of Scientific and Technical Information (OSTI.GOV)

Preston, Leiph

Although using standard Taylor series coefficients for finite-difference operators is optimal in the sense that in the limit of infinitesimal space and time discretization, the solution approaches the correct analytic solution to the acousto-dynamic system of differential equations, other finite-difference operators may provide optimal computational run time given certain error bounds or source bandwidth constraints. This report describes the results of investigation of alternative optimal finite-difference coefficients based on several optimization/accuracy scenarios and provides recommendations for minimizing run time while retaining error within given error bounds.

SSC Geopositional Assessment of the Advanced Wide Field Sensor

NASA Technical Reports Server (NTRS)

Ross, Kenton

2006-01-01

The geopositional accuracy of the standard geocorrected product from the Advanced Wide Field Sensor (AWiFS) was evaluated using digital orthophoto quarter quadrangles and other reference sources of similar accuracy. Images were analyzed from summer 2004 through spring 2005. Forty to fifty check points were collected manually per scene and analyzed to determine overall circular error, estimates of horizontal bias, and other systematic errors. Measured errors were somewhat higher than the specifications for the data, but they were consistent with the analysis of the distributing vendor.

Cost-effectiveness of the U.S. Geological Survey's stream-gaging programs in Massachusetts and Rhode Island

USGS Publications Warehouse

Gadoury, R.A.; Smath, J.A.; Fontaine, R.A.

1985-01-01

The report documents the results of a study of the cost-effectiveness of the U.S. Geological Survey 's continuous-record stream-gaging programs in Massachusetts and Rhode Island. Data uses and funding sources were identified for 91 gaging stations being operated in Massachusetts are being operated to provide data for two special purpose hydrologic studies, and they are planned to be discontinued at the conclusion of the studies. Cost-effectiveness analyses were performed on 63 continuous-record gaging stations in Massachusetts and 15 stations in Rhode Island, at budgets of $353,000 and $60,500, respectively. Current operations policies result in average standard errors per station of 12.3% in Massachusetts and 9.7% in Rhode Island. Minimum possible budgets to maintain the present numbers of gaging stations in the two States are estimated to be $340,000 and $59,000, with average errors per station of 12.8% and 10.0%, respectively. If the present budget levels were doubled, average standards errors per station would decrease to 8.1% and 4.2%, respectively. Further budget increases would not improve the standard errors significantly. (USGS)

Revised techniques for estimating peak discharges from channel width in Montana

USGS Publications Warehouse

Parrett, Charles; Hull, J.A.; Omang, R.J.

1987-01-01

This study was conducted to develop new estimating equations based on channel width and the updated flood frequency curves of previous investigations. Simple regression equations for estimating peak discharges with recurrence intervals of 2, 5, 10 , 25, 50, and 100 years were developed for seven regions in Montana. The standard errors of estimates for the equations that use active channel width as the independent variables ranged from 30% to 87%. The standard errors of estimate for the equations that use bankfull width as the independent variable ranged from 34% to 92%. The smallest standard errors generally occurred in the prediction equations for the 2-yr flood, 5-yr flood, and 10-yr flood, and the largest standard errors occurred in the prediction equations for the 100-yr flood. The equations that use active channel width and the equations that use bankfull width were determined to be about equally reliable in five regions. In the West Region, the equations that use bankfull width were slightly more reliable than those based on active channel width, whereas in the East-Central Region the equations that use active channel width were slightly more reliable than those based on bankfull width. Compared with similar equations previously developed, the standard errors of estimate for the new equations are substantially smaller in three regions and substantially larger in two regions. Limitations on the use of the estimating equations include: (1) The equations are based on stable conditions of channel geometry and prevailing water and sediment discharge; (2) The measurement of channel width requires a site visit, preferably by a person with experience in the method, and involves appreciable measurement errors; (3) Reliability of results from the equations for channel widths beyond the range of definition is unknown. In spite of the limitations, the estimating equations derived in this study are considered to be as reliable as estimating equations based on basin and climatic variables. Because the two types of estimating equations are independent, results from each can be weighted inversely proportional to their variances, and averaged. The weighted average estimate has a variance less than either individual estimate. (Author 's abstract)

Standardized error severity score (ESS) ratings to quantify risk associated with child restraint system (CRS) and booster seat misuse.

PubMed

Rudin-Brown, Christina M; Kramer, Chelsea; Langerak, Robin; Scipione, Andrea; Kelsey, Shelley

2017-11-17

Although numerous research studies have reported high levels of error and misuse of child restraint systems (CRS) and booster seats in experimental and real-world scenarios, conclusions are limited because they provide little information regarding which installation issues pose the highest risk and thus should be targeted for change. Beneficial to legislating bodies and researchers alike would be a standardized, globally relevant assessment of the potential injury risk associated with more common forms of CRS and booster seat misuse, which could be applied with observed error frequency-for example, in car seat clinics or during prototype user testing-to better identify and characterize the installation issues of greatest risk to safety. A group of 8 leading world experts in CRS and injury biomechanics, who were members of an international child safety project, estimated the potential injury severity associated with common forms of CRS and booster seat misuse. These injury risk error severity score (ESS) ratings were compiled and compared to scores from previous research that had used a similar procedure but with fewer respondents. To illustrate their application, and as part of a larger study examining CRS and booster seat labeling requirements, the new standardized ESS ratings were applied to objective installation performance data from 26 adult participants who installed a convertible (rear- vs. forward-facing) CRS and booster seat in a vehicle, and a child test dummy in the CRS and booster seat, using labels that only just met minimal regulatory requirements. The outcome measure, the risk priority number (RPN), represented the composite scores of injury risk and observed installation error frequency. Variability within the sample of ESS ratings in the present study was smaller than that generated in previous studies, indicating better agreement among experts on what constituted injury risk. Application of the new standardized ESS ratings to installation performance data revealed several areas of misuse of the CRS/booster seat associated with high potential injury risk. Collectively, findings indicate that standardized ESS ratings are useful for estimating injury risk potential associated with real-world CRS and booster seat installation errors.

Modified Redundancy based Technique—a New Approach to Combat Error Propagation Effect of AES

NASA Astrophysics Data System (ADS)

Sarkar, B.; Bhunia, C. T.; Maulik, U.

2012-06-01

Advanced encryption standard (AES) is a great research challenge. It has been developed to replace the data encryption standard (DES). AES suffers from a major limitation of error propagation effect. To tackle this limitation, two methods are available. One is redundancy based technique and the other one is bite based parity technique. The first one has a significant advantage of correcting any error on definite term over the second one but at the cost of higher level of overhead and hence lowering the processing speed. In this paper, a new approach based on the redundancy based technique is proposed that would certainly speed up the process of reliable encryption and hence the secured communication.

Flow interference in a variable porosity trisonic wind tunnel.

NASA Technical Reports Server (NTRS)

Davis, J. W.; Graham, R. F.

1972-01-01

Pressure data from a 20-degree cone-cylinder in a variable porosity wind tunnel for the Mach range 0.2 to 5.0 are compared to an interference free standard in order to determine wall interference effects. Four 20-degree cone-cylinder models representing an approximate range of percent blockage from one to six were compared to curve-fits of the interference free standard at each Mach number and errors determined at each pressure tap location. The average of the absolute values of the percent error over the length of the model was determined and used as the criterion for evaluating model blockage interference effects. The results are presented in the form of the percent error as a function of model blockage and Mach number.

Error-trellis Syndrome Decoding Techniques for Convolutional Codes

NASA Technical Reports Server (NTRS)

Reed, I. S.; Truong, T. K.

1984-01-01

An error-trellis syndrome decoding technique for convolutional codes is developed. This algorithm is then applied to the entire class of systematic convolutional codes and to the high-rate, Wyner-Ash convolutional codes. A special example of the one-error-correcting Wyner-Ash code, a rate 3/4 code, is treated. The error-trellis syndrome decoding method applied to this example shows in detail how much more efficient syndrome decoding is than Viterbi decoding if applied to the same problem. For standard Viterbi decoding, 64 states are required, whereas in the example only 7 states are needed. Also, within the 7 states required for decoding, many fewer transitions are needed between the states.

Error-trellis syndrome decoding techniques for convolutional codes

NASA Technical Reports Server (NTRS)

Reed, I. S.; Truong, T. K.

1985-01-01

An error-trellis syndrome decoding technique for convolutional codes is developed. This algorithm is then applied to the entire class of systematic convolutional codes and to the high-rate, Wyner-Ash convolutional codes. A special example of the one-error-correcting Wyner-Ash code, a rate 3/4 code, is treated. The error-trellis syndrome decoding method applied to this example shows in detail how much more efficient syndrome decordig is than Viterbi decoding if applied to the same problem. For standard Viterbi decoding, 64 states are required, whereas in the example only 7 states are needed. Also, within the 7 states required for decoding, many fewer transitions are needed between the states.

Bandwagon effects and error bars in particle physics

NASA Astrophysics Data System (ADS)

Jeng, Monwhea

2007-02-01

We study historical records of experiments on particle masses, lifetimes, and widths, both for signs of expectation bias, and to compare actual errors with reported error bars. We show that significant numbers of particle properties exhibit "bandwagon effects": reported values show trends and clustering as a function of the year of publication, rather than random scatter about the mean. While the total amount of clustering is significant, it is also fairly small; most individual particle properties do not display obvious clustering. When differences between experiments are compared with the reported error bars, the deviations do not follow a normal distribution, but instead follow an exponential distribution for up to ten standard deviations.

Noise Estimation and Adaptive Encoding for Asymmetric Quantum Error Correcting Codes

NASA Astrophysics Data System (ADS)

Florjanczyk, Jan; Brun, Todd; CenterQuantum Information Science; Technology Team

We present a technique that improves the performance of asymmetric quantum error correcting codes in the presence of biased qubit noise channels. Our study is motivated by considering what useful information can be learned from the statistics of syndrome measurements in stabilizer quantum error correcting codes (QECC). We consider the case of a qubit dephasing channel where the dephasing axis is unknown and time-varying. We are able to estimate the dephasing angle from the statistics of the standard syndrome measurements used in stabilizer QECC's. We use this estimate to rotate the computational basis of the code in such a way that the most likely type of error is covered by the highest distance of the asymmetric code. In particular, we use the [ [ 15 , 1 , 3 ] ] shortened Reed-Muller code which can correct one phase-flip error but up to three bit-flip errors. In our simulations, we tune the computational basis to match the estimated dephasing axis which in turn leads to a decrease in the probability of a phase-flip error. With a sufficiently accurate estimate of the dephasing axis, our memory's effective error is dominated by the much lower probability of four bit-flips. Aro MURI Grant No. W911NF-11-1-0268.

Peripheral Quantitative Computed Tomography: Measurement Sensitivity in Persons With and Without Spinal Cord Injury

PubMed Central

Shields, Richard K.; Dudley-Javoroski, Shauna; Boaldin, Kathryn M.; Corey, Trent A.; Fog, Daniel B.; Ruen, Jacquelyn M.

2012-01-01

Objectives To determine (1) the error attributable to external tibia-length measurements by using peripheral quantitative computed tomography (pQCT) and (2) the effect these errors have on scan location and tibia trabecular bone mineral density (BMD) after spinal cord injury (SCI). Design Blinded comparison and criterion standard in matched cohorts. Setting Primary care university hospital. Participants Eight able-bodied subjects underwent tibia length measurement. A separate cohort of 7 men with SCI and 7 able-bodied age-matched male controls underwent pQCT analysis. Interventions Not applicable. Main Outcome Measures The projected worst-case tibia-length–measurement error translated into a pQCT slice placement error of ±3mm. We collected pQCT slices at the distal 4% tibia site, 3mm proximal and 3mm distal to that site, and then quantified BMD error attributable to slice placement. Results Absolute BMD error was greater for able-bodied than for SCI subjects (5.87mg/cm3 vs 4.5mg/cm3). However, the percentage error in BMD was larger for SCI than able-bodied subjects (4.56% vs 2.23%). Conclusions During cross-sectional studies of various populations, BMD differences up to 5% may be attributable to variation in limb-length–measurement error. PMID:17023249

Acoustic holography as a metrological tool for characterizing medical ultrasound sources and fields

PubMed Central

Sapozhnikov, Oleg A.; Tsysar, Sergey A.; Khokhlova, Vera A.; Kreider, Wayne

2015-01-01

Acoustic holography is a powerful technique for characterizing ultrasound sources and the fields they radiate, with the ability to quantify source vibrations and reduce the number of required measurements. These capabilities are increasingly appealing for meeting measurement standards in medical ultrasound; however, associated uncertainties have not been investigated systematically. Here errors associated with holographic representations of a linear, continuous-wave ultrasound field are studied. To facilitate the analysis, error metrics are defined explicitly, and a detailed description of a holography formulation based on the Rayleigh integral is provided. Errors are evaluated both for simulations of a typical therapeutic ultrasound source and for physical experiments with three different ultrasound sources. Simulated experiments explore sampling errors introduced by the use of a finite number of measurements, geometric uncertainties in the actual positions of acquired measurements, and uncertainties in the properties of the propagation medium. Results demonstrate the theoretical feasibility of keeping errors less than about 1%. Typical errors in physical experiments were somewhat larger, on the order of a few percent; comparison with simulations provides specific guidelines for improving the experimental implementation to reduce these errors. Overall, results suggest that holography can be implemented successfully as a metrological tool with small, quantifiable errors. PMID:26428789

A concatenated coding scheme for error control

NASA Technical Reports Server (NTRS)

Lin, S.

1985-01-01

A concatenated coding scheme for error control in data communications is analyzed. The inner code is used for both error correction and detection, however the outer code is used only for error detection. A retransmission is requested if the outer code detects the presence of errors after the inner code decoding. The probability of undetected error of the above error control scheme is derived and upper bounded. Two specific exmaples are analyzed. In the first example, the inner code is a distance-4 shortened Hamming code with generator polynomial (X+1)(X(6)+X+1) = X(7)+X(6)+X(2)+1 and the outer code is a distance-4 shortened Hamming code with generator polynomial (X+1)X(15+X(14)+X(13)+X(12)+X(4)+X(3)+X(2)+X+1) = X(16)+X(12)+X(5)+1 which is the X.25 standard for packet-switched data network. This example is proposed for error control on NASA telecommand links. In the second example, the inner code is the same as that in the first example but the outer code is a shortened Reed-Solomon code with symbols from GF(2(8)) and generator polynomial (X+1)(X+alpha) where alpha is a primitive element in GF(z(8)).

Effects of Random Shadings, Phasing Errors, and Element Failures on the Beam Patterns of Linear and Planar Arrays

DTIC Science & Technology

1980-03-14

failure Sigmar (Or) in line 50, the standard deviation of the relative error of the weights Sigmap (o) in line 60, the standard deviation of the phase...200, the weight structures in the x and y coordinates Q in line 210, the probability of element failure Sigmar (Or) in line 220, the standard...NUMBER OF ELEMENTS =u;2*H 120 PRINT "Pr’obability of elemenit failure al;O 130 PRINT "Standard dtvi&t ion’ oe r.1&tive ýrror of wl; Sigmar 14 0 PRINT

Decision Making for Borderline Cases in Pass/Fail Clinical Anatomy Courses: The Practical Value of the Standard Error of Measurement and Likelihood Ratio in a Diagnostic Test

ERIC Educational Resources Information Center

Severo, Milton; Silva-Pereira, Fernanda; Ferreira, Maria Amelia

2013-01-01

Several studies have shown that the standard error of measurement (SEM) can be used as an additional “safety net” to reduce the frequency of false-positive or false-negative student grading classifications. Practical examinations in clinical anatomy are often used as diagnostic tests to admit students to course final examinations. The aim of this…

Worldwide Survey of Alcohol and Nonmedical Drug Use among Military Personnel: 1982,

DTIC Science & Technology

1983-01-01

cell . The first number is an estimate of the percentage of the population with the characteristics that define the cell . The second number, in...multiplying 1.96 times the standard error for that cell . (Obviously, for very small or very large estimates, the respective smallest or largest value in...that the cell proportions estimate the true population value more precisely, and larger standard errors indicate that the true population value is

Design and simulation study of the immunization Data Quality Audit (DQA).

PubMed

Woodard, Stacy; Archer, Linda; Zell, Elizabeth; Ronveaux, Olivier; Birmingham, Maureen

2007-08-01

The goal of the Data Quality Audit (DQA) is to assess whether the Global Alliance for Vaccines and Immunization-funded countries are adequately reporting the number of diphtheria-tetanus-pertussis immunizations given, on which the "shares" are awarded. Given that this sampling design is a modified two-stage cluster sample (modified because a stratified, rather than a simple, random sample of health facilities is obtained from the selected clusters); the formula for the calculation of the standard error for the estimate is unknown. An approximated standard error has been proposed, and the first goal of this simulation is to assess the accuracy of the standard error. Results from the simulations based on hypothetical populations were found not to be representative of the actual DQAs that were conducted. Additional simulations were then conducted on the actual DQA data to better access the precision of the DQ with both the original and the increased sample sizes.

Parameter recovery, bias and standard errors in the linear ballistic accumulator model.

PubMed

Visser, Ingmar; Poessé, Rens

2017-05-01

The linear ballistic accumulator (LBA) model (Brown & Heathcote, , Cogn. Psychol., 57, 153) is increasingly popular in modelling response times from experimental data. An R package, glba, has been developed to fit the LBA model using maximum likelihood estimation which is validated by means of a parameter recovery study. At sufficient sample sizes parameter recovery is good, whereas at smaller sample sizes there can be large bias in parameters. In a second simulation study, two methods for computing parameter standard errors are compared. The Hessian-based method is found to be adequate and is (much) faster than the alternative bootstrap method. The use of parameter standard errors in model selection and inference is illustrated in an example using data from an implicit learning experiment (Visser et al., , Mem. Cogn., 35, 1502). It is shown that typical implicit learning effects are captured by different parameters of the LBA model. © 2017 The British Psychological Society.

Lognormal kriging for the assessment of reliability in groundwater quality control observation networks

USGS Publications Warehouse

Candela, L.; Olea, R.A.; Custodio, E.

1988-01-01

Groundwater quality observation networks are examples of discontinuous sampling on variables presenting spatial continuity and highly skewed frequency distributions. Anywhere in the aquifer, lognormal kriging provides estimates of the variable being sampled and a standard error of the estimate. The average and the maximum standard error within the network can be used to dynamically improve the network sampling efficiency or find a design able to assure a given reliability level. The approach does not require the formulation of any physical model for the aquifer or any actual sampling of hypothetical configurations. A case study is presented using the network monitoring salty water intrusion into the Llobregat delta confined aquifer, Barcelona, Spain. The variable chloride concentration used to trace the intrusion exhibits sudden changes within short distances which make the standard error fairly invariable to changes in sampling pattern and to substantial fluctuations in the number of wells. ?? 1988.

De-biasing the dynamic mode decomposition for applied Koopman spectral analysis of noisy datasets

NASA Astrophysics Data System (ADS)

Hemati, Maziar S.; Rowley, Clarence W.; Deem, Eric A.; Cattafesta, Louis N.

2017-08-01

The dynamic mode decomposition (DMD)—a popular method for performing data-driven Koopman spectral analysis—has gained increased popularity for extracting dynamically meaningful spatiotemporal descriptions of fluid flows from snapshot measurements. Often times, DMD descriptions can be used for predictive purposes as well, which enables informed decision-making based on DMD model forecasts. Despite its widespread use and utility, DMD can fail to yield accurate dynamical descriptions when the measured snapshot data are imprecise due to, e.g., sensor noise. Here, we express DMD as a two-stage algorithm in order to isolate a source of systematic error. We show that DMD's first stage, a subspace projection step, systematically introduces bias errors by processing snapshots asymmetrically. To remove this systematic error, we propose utilizing an augmented snapshot matrix in a subspace projection step, as in problems of total least-squares, in order to account for the error present in all snapshots. The resulting unbiased and noise-aware total DMD (TDMD) formulation reduces to standard DMD in the absence of snapshot errors, while the two-stage perspective generalizes the de-biasing framework to other related methods as well. TDMD's performance is demonstrated in numerical and experimental fluids examples. In particular, in the analysis of time-resolved particle image velocimetry data for a separated flow, TDMD outperforms standard DMD by providing dynamical interpretations that are consistent with alternative analysis techniques. Further, TDMD extracts modes that reveal detailed spatial structures missed by standard DMD.

34 CFR 682.410 - Fiscal, administrative, and enforcement requirements.

Code of Federal Regulations, 2011 CFR

2011-07-01

... accordance with applicable legal and accounting standards; (iii) The Secretary's equitable share of... any other errors in its accounting or reporting as soon as practicable after the errors become known... guaranty agency's agreements with the Secretary; and (C) Market prices of comparable goods or services. (b...

10 CFR 74.59 - Quality assurance and accounting requirements.

Code of Federal Regulations, 2013 CFR

2013-01-01

... occurs which has the potential to affect a measurement result or when program data, generated by tests.../receiver differences, inventory differences, and process differences. (4) Utilize the data generated during... difference (SEID) and the standard error of the process differences. Calibration and measurement error data...

10 CFR 74.59 - Quality assurance and accounting requirements.

Code of Federal Regulations, 2014 CFR

2014-01-01

... occurs which has the potential to affect a measurement result or when program data, generated by tests.../receiver differences, inventory differences, and process differences. (4) Utilize the data generated during... difference (SEID) and the standard error of the process differences. Calibration and measurement error data...

48 CFR 622.404-7 - Correction of wage determinations containing clerical errors.

Code of Federal Regulations, 2010 CFR

2010-10-01

... DEPARTMENT OF STATE SOCIOECONOMIC PROGRAMS APPLICATION OF LABOR LAWS TO GOVERNMENT ACQUISITIONS Labor Standards for Contracts Involving Construction 622.404-7 Correction of wage determinations containing clerical errors. The cognizant contracting activity is the contracting agency for the purposes of FAR 22...

Qualitative Examination of Children's Naming Skills through Test Adaptations.

ERIC Educational Resources Information Center

Fried-Oken, Melanie

1987-01-01

The Double Administration Naming Technique assists clinicians in obtaining qualitative information about a client's visual confrontation naming skills through administration of a standard naming test; readministration of the same test; identification of single and double errors; cuing for double naming errors; and qualitative analysis of naming…

Field evaluation of the error arising from inadequate time averaging in the standard use of depth-integrating suspended-sediment samplers

USGS Publications Warehouse

Topping, David J.; Rubin, David M.; Wright, Scott A.; Melis, Theodore S.

2011-01-01

Several common methods for measuring suspended-sediment concentration in rivers in the United States use depth-integrating samplers to collect a velocity-weighted suspended-sediment sample in a subsample of a river cross section. Because depth-integrating samplers are always moving through the water column as they collect a sample, and can collect only a limited volume of water and suspended sediment, they collect only minimally time-averaged data. Four sources of error exist in the field use of these samplers: (1) bed contamination, (2) pressure-driven inrush, (3) inadequate sampling of the cross-stream spatial structure in suspended-sediment concentration, and (4) inadequate time averaging. The first two of these errors arise from misuse of suspended-sediment samplers, and the third has been the subject of previous study using data collected in the sand-bedded Middle Loup River in Nebraska. Of these four sources of error, the least understood source of error arises from the fact that depth-integrating samplers collect only minimally time-averaged data. To evaluate this fourth source of error, we collected suspended-sediment data between 1995 and 2007 at four sites on the Colorado River in Utah and Arizona, using a P-61 suspended-sediment sampler deployed in both point- and one-way depth-integrating modes, and D-96-A1 and D-77 bag-type depth-integrating suspended-sediment samplers. These data indicate that the minimal duration of time averaging during standard field operation of depth-integrating samplers leads to an error that is comparable in magnitude to that arising from inadequate sampling of the cross-stream spatial structure in suspended-sediment concentration. This random error arising from inadequate time averaging is positively correlated with grain size and does not largely depend on flow conditions or, for a given size class of suspended sediment, on elevation above the bed. Averaging over time scales >1 minute is the likely minimum duration required to result in substantial decreases in this error. During standard two-way depth integration, a depth-integrating suspended-sediment sampler collects a sample of the water-sediment mixture during two transits at each vertical in a cross section: one transit while moving from the water surface to the bed, and another transit while moving from the bed to the water surface. As the number of transits is doubled at an individual vertical, this error is reduced by ~30 percent in each size class of suspended sediment. For a given size class of suspended sediment, the error arising from inadequate sampling of the cross-stream spatial structure in suspended-sediment concentration depends only on the number of verticals collected, whereas the error arising from inadequate time averaging depends on both the number of verticals collected and the number of transits collected at each vertical. Summing these two errors in quadrature yields a total uncertainty in an equal-discharge-increment (EDI) or equal-width-increment (EWI) measurement of the time-averaged velocity-weighted suspended-sediment concentration in a river cross section (exclusive of any laboratory-processing errors). By virtue of how the number of verticals and transits influences the two individual errors within this total uncertainty, the error arising from inadequate time averaging slightly dominates that arising from inadequate sampling of the cross-stream spatial structure in suspended-sediment concentration. Adding verticals to an EDI or EWI measurement is slightly more effective in reducing the total uncertainty than adding transits only at each vertical, because a new vertical contributes both temporal and spatial information. However, because collection of depth-integrated samples at more transits at each vertical is generally easier and faster than at more verticals, addition of a combination of verticals and transits is likely a more practical approach to reducing the total uncertainty in most field situatio

Ad hoc versus standardized admixtures for continuous infusion drugs in neonatal intensive care: cognitive task analysis of safety at the bedside.

PubMed

Brannon, Timothy S

2006-01-01

Continuous infusion intravenous (IV) drugs in neonatal intensive care are usually prepared based on patient weight so that the dose is readable as a simple multiple of the infusion pump rate. New safety guidelines propose that hospitals switch to using standardized admixtures of these drugs to prevent calculation errors during ad hoc preparation. Extended hierarchical task analysis suggests that switching to standardized admixtures may lead to more errors in programming the pump at the bedside.

Ad Hoc versus Standardized Admixtures for Continuous Infusion Drugs in Neonatal Intensive Care: Cognitive Task Analysis of Safety at the Bedside

PubMed Central

Brannon, Timothy S.

2006-01-01

Continuous infusion intravenous (IV) drugs in neonatal intensive care are usually prepared based on patient weight so that the dose is readable as a simple multiple of the infusion pump rate. New safety guidelines propose that hospitals switch to using standardized admixtures of these drugs to prevent calculation errors during ad hoc preparation. Extended hierarchical task analysis suggests that switching to standardized admixtures may lead to more errors in programming the pump at the bedside. PMID:17238482

Cognitive tests predict real-world errors: the relationship between drug name confusion rates in laboratory-based memory and perception tests and corresponding error rates in large pharmacy chains

PubMed Central

Schroeder, Scott R; Salomon, Meghan M; Galanter, William L; Schiff, Gordon D; Vaida, Allen J; Gaunt, Michael J; Bryson, Michelle L; Rash, Christine; Falck, Suzanne; Lambert, Bruce L

2017-01-01

Background Drug name confusion is a common type of medication error and a persistent threat to patient safety. In the USA, roughly one per thousand prescriptions results in the wrong drug being filled, and most of these errors involve drug names that look or sound alike. Prior to approval, drug names undergo a variety of tests to assess their potential for confusability, but none of these preapproval tests has been shown to predict real-world error rates. Objectives We conducted a study to assess the association between error rates in laboratory-based tests of drug name memory and perception and real-world drug name confusion error rates. Methods Eighty participants, comprising doctors, nurses, pharmacists, technicians and lay people, completed a battery of laboratory tests assessing visual perception, auditory perception and short-term memory of look-alike and sound-alike drug name pairs (eg, hydroxyzine/hydralazine). Results Laboratory test error rates (and other metrics) significantly predicted real-world error rates obtained from a large, outpatient pharmacy chain, with the best-fitting model accounting for 37% of the variance in real-world error rates. Cross-validation analyses confirmed these results, showing that the laboratory tests also predicted errors from a second pharmacy chain, with 45% of the variance being explained by the laboratory test data. Conclusions Across two distinct pharmacy chains, there is a strong and significant association between drug name confusion error rates observed in the real world and those observed in laboratory-based tests of memory and perception. Regulators and drug companies seeking a validated preapproval method for identifying confusing drug names ought to consider using these simple tests. By using a standard battery of memory and perception tests, it should be possible to reduce the number of confusing look-alike and sound-alike drug name pairs that reach the market, which will help protect patients from potentially harmful medication errors. PMID:27193033

Death Certification Errors and the Effect on Mortality Statistics.

PubMed

McGivern, Lauri; Shulman, Leanne; Carney, Jan K; Shapiro, Steven; Bundock, Elizabeth

Errors in cause and manner of death on death certificates are common and affect families, mortality statistics, and public health research. The primary objective of this study was to characterize errors in the cause and manner of death on death certificates completed by non-Medical Examiners. A secondary objective was to determine the effects of errors on national mortality statistics. We retrospectively compared 601 death certificates completed between July 1, 2015, and January 31, 2016, from the Vermont Electronic Death Registration System with clinical summaries from medical records. Medical Examiners, blinded to original certificates, reviewed summaries, generated mock certificates, and compared mock certificates with original certificates. They then graded errors using a scale from 1 to 4 (higher numbers indicated increased impact on interpretation of the cause) to determine the prevalence of minor and major errors. They also compared International Classification of Diseases, 10th Revision (ICD-10) codes on original certificates with those on mock certificates. Of 601 original death certificates, 319 (53%) had errors; 305 (51%) had major errors; and 59 (10%) had minor errors. We found no significant differences by certifier type (physician vs nonphysician). We did find significant differences in major errors in place of death ( P < .001). Certificates for deaths occurring in hospitals were more likely to have major errors than certificates for deaths occurring at a private residence (59% vs 39%, P < .001). A total of 580 (93%) death certificates had a change in ICD-10 codes between the original and mock certificates, of which 348 (60%) had a change in the underlying cause-of-death code. Error rates on death certificates in Vermont are high and extend to ICD-10 coding, thereby affecting national mortality statistics. Surveillance and certifier education must expand beyond local and state efforts. Simplifying and standardizing underlying literal text for cause of death may improve accuracy, decrease coding errors, and improve national mortality statistics.

Determination of Barometric Altimeter Errors for the Orion Exploration Flight Test-1 Entry

NASA Technical Reports Server (NTRS)

Brown, Denise L.; Munoz, Jean-Philippe; Gay, Robert

2011-01-01

The EFT-1 mission is the unmanned flight test for the upcoming Multi-Purpose Crew Vehicle (MPCV). During entry, the EFT-1 vehicle will trigger several Landing and Recovery System (LRS) events, such as parachute deployment, based on onboard altitude information. The primary altitude source is the filtered navigation solution updated with GPS measurement data. The vehicle also has three barometric altimeters that will be used to measure atmospheric pressure during entry. In the event that GPS data is not available during entry, the altitude derived from the barometric altimeter pressure will be used to trigger chute deployment for the drogues and main parachutes. Therefore it is important to understand the impact of error sources on the pressure measured by the barometric altimeters and on the altitude derived from that pressure. There are four primary error sources impacting the sensed pressure: sensor errors, Analog to Digital conversion errors, aerodynamic errors, and atmosphere modeling errors. This last error source is induced by the conversion from pressure to altitude in the vehicle flight software, which requires an atmosphere model such as the US Standard 1976 Atmosphere model. There are several secondary error sources as well, such as waves, tides, and latencies in data transmission. Typically, for error budget calculations it is assumed that all error sources are independent, normally distributed variables. Thus, the initial approach to developing the EFT-1 barometric altimeter altitude error budget was to create an itemized error budget under these assumptions. This budget was to be verified by simulation using high fidelity models of the vehicle hardware and software. The simulation barometric altimeter model includes hardware error sources and a data-driven model of the aerodynamic errors expected to impact the pressure in the midbay compartment in which the sensors are located. The aerodynamic model includes the pressure difference between the midbay compartment and the free stream pressure as a function of altitude, oscillations in sensed pressure due to wake effects, and an acoustics model capturing fluctuations in pressure due to motion of the passive vents separating the barometric altimeters from the outside of the vehicle.

Dental Students' Interpretations of Digital Panoramic Radiographs on Completely Edentate Patients.

PubMed

Kratz, Richard J; Nguyen, Caroline T; Walton, Joanne N; MacDonald, David

2018-03-01

The ability of dental students to interpret digital panoramic radiographs (PANs) of edentulous patients has not been documented. The aim of this retrospective study was to compare the ability of second-year (D2) dental students with that of third- and fourth-year (D3-D4) dental students to interpret and identify positional errors in digital PANs obtained from patients with complete edentulism. A total of 169 digital PANs from edentulous patients were assessed by D2 (n=84) and D3-D4 (n=85) dental students at one Canadian dental school. The correctness of the students' interpretations was determined by comparison to a gold standard established by assessments of the same PANs by two experts (a graduate student in prosthodontics and an oral and maxillofacial radiologist). Data collected were from September 1, 2006, when digital radiography was implemented at the university, to December 31, 2012. Nearly all (95%) of the PANs were acceptable diagnostically despite a high proportion (92%) of positional errors detected. A total of 301 positional errors were identified in the sample. The D2 students identified significantly more (p=0.002) positional errors than the D3-D4 students. There was no significant difference (p=0.059) in the distribution of radiographic interpretation errors between the two student groups when compared to the gold standard. Overall, the category of extragnathic findings had the highest number of false negatives (43) reported. In this study, dental students interpreted digital PANs of edentulous patients satisfactorily, but they were more adept at identifying radiographic findings compared to positional errors. Students should be reminded to examine the entire radiograph thoroughly to ensure extragnathic findings are not missed and to recognize and report patient positional errors.

An Assessment of State-of-the-Art Mean Sea Surface and Geoid Models of the Arctic Ocean: Implications for Sea Ice Freeboard Retrieval

NASA Astrophysics Data System (ADS)

Skourup, Henriette; Farrell, Sinéad Louise; Hendricks, Stefan; Ricker, Robert; Armitage, Thomas W. K.; Ridout, Andy; Andersen, Ole Baltazar; Haas, Christian; Baker, Steven

2017-11-01

State-of-the-art Arctic Ocean mean sea surface (MSS) models and global geoid models (GGMs) are used to support sea ice freeboard estimation from satellite altimeters, as well as in oceanographic studies such as mapping sea level anomalies and mean dynamic ocean topography. However, errors in a given model in the high-frequency domain, primarily due to unresolved gravity features, can result in errors in the estimated along-track freeboard. These errors are exacerbated in areas with a sparse lead distribution in consolidated ice pack conditions. Additionally model errors can impact ocean geostrophic currents, derived from satellite altimeter data, while remaining biases in these models may impact longer-term, multisensor oceanographic time series of sea level change in the Arctic. This study focuses on an assessment of five state-of-the-art Arctic MSS models (UCL13/04 and DTU15/13/10) and a commonly used GGM (EGM2008). We describe errors due to unresolved gravity features, intersatellite biases, and remaining satellite orbit errors, and their impact on the derivation of sea ice freeboard. The latest MSS models, incorporating CryoSat-2 sea surface height measurements, show improved definition of gravity features, such as the Gakkel Ridge. The standard deviation between models ranges 0.03-0.25 m. The impact of remaining MSS/GGM errors on freeboard retrieval can reach several decimeters in parts of the Arctic. While the maximum observed freeboard difference found in the central Arctic was 0.59 m (UCL13 MSS minus EGM2008 GGM), the standard deviation in freeboard differences is 0.03-0.06 m.

Multivariate Statistics Applied to Seismic Phase Picking

NASA Astrophysics Data System (ADS)

Velasco, A. A.; Zeiler, C. P.; Anderson, D.; Pingitore, N. E.

2008-12-01

The initial effort of the Seismogram Picking Error from Analyst Review (SPEAR) project has been to establish a common set of seismograms to be picked by the seismological community. Currently we have 13 analysts from 4 institutions that have provided picks on the set of 26 seismograms. In comparing the picks thus far, we have identified consistent biases between picks from different institutions; effects of the experience of analysts; and the impact of signal-to-noise on picks. The institutional bias in picks brings up the important concern that picks will not be the same between different catalogs. This difference means less precision and accuracy when combing picks from multiple institutions. We also note that depending on the experience level of the analyst making picks for a catalog the error could fluctuate dramatically. However, the experience level is based off of number of years in picking seismograms and this may not be an appropriate criterion for determining an analyst's precision. The common data set of seismograms provides a means to test an analyst's level of precision and biases. The analyst is also limited by the quality of the signal and we show that the signal-to-noise ratio and pick error are correlated to the location, size and distance of the event. This makes the standard estimate of picking error based on SNR more complex because additional constraints are needed to accurately constrain the measurement error. We propose to extend the current measurement of error by adding the additional constraints of institutional bias and event characteristics to the standard SNR measurement. We use multivariate statistics to model the data and provide constraints to accurately assess earthquake location and measurement errors.

Self-test web-based pure-tone audiometry: validity evaluation and measurement error analysis.

PubMed

Masalski, Marcin; Kręcicki, Tomasz

2013-04-12

Potential methods of application of self-administered Web-based pure-tone audiometry conducted at home on a PC with a sound card and ordinary headphones depend on the value of measurement error in such tests. The aim of this research was to determine the measurement error of the hearing threshold determined in the way described above and to identify and analyze factors influencing its value. The evaluation of the hearing threshold was made in three series: (1) tests on a clinical audiometer, (2) self-tests done on a specially calibrated computer under the supervision of an audiologist, and (3) self-tests conducted at home. The research was carried out on the group of 51 participants selected from patients of an audiology outpatient clinic. From the group of 51 patients examined in the first two series, the third series was self-administered at home by 37 subjects (73%). The average difference between the value of the hearing threshold determined in series 1 and in series 2 was -1.54dB with standard deviation of 7.88dB and a Pearson correlation coefficient of .90. Between the first and third series, these values were -1.35dB±10.66dB and .84, respectively. In series 3, the standard deviation was most influenced by the error connected with the procedure of hearing threshold identification (6.64dB), calibration error (6.19dB), and additionally at the frequency of 250Hz by frequency nonlinearity error (7.28dB). The obtained results confirm the possibility of applying Web-based pure-tone audiometry in screening tests. In the future, modifications of the method leading to the decrease in measurement error can broaden the scope of Web-based pure-tone audiometry application.

Error analysis of mechanical system and wavelength calibration of monochromator

NASA Astrophysics Data System (ADS)

Zhang, Fudong; Chen, Chen; Liu, Jie; Wang, Zhihong

2018-02-01

This study focuses on improving the accuracy of a grating monochromator on the basis of the grating diffraction equation in combination with an analysis of the mechanical transmission relationship between the grating, the sine bar, and the screw of the scanning mechanism. First, the relationship between the mechanical error in the monochromator with the sine drive and the wavelength error is analyzed. Second, a mathematical model of the wavelength error and mechanical error is developed, and an accurate wavelength calibration method based on the sine bar's length adjustment and error compensation is proposed. Based on the mathematical model and calibration method, experiments using a standard light source with known spectral lines and a pre-adjusted sine bar length are conducted. The model parameter equations are solved, and subsequent parameter optimization simulations are performed to determine the optimal length ratio. Lastly, the length of the sine bar is adjusted. The experimental results indicate that the wavelength accuracy is ±0.3 nm, which is better than the original accuracy of ±2.6 nm. The results confirm the validity of the error analysis of the mechanical system of the monochromator as well as the validity of the calibration method.

Experimental investigation of observation error in anuran call surveys

USGS Publications Warehouse

McClintock, B.T.; Bailey, L.L.; Pollock, K.H.; Simons, T.R.

2010-01-01

Occupancy models that account for imperfect detection are often used to monitor anuran and songbird species occurrence. However, presenceabsence data arising from auditory detections may be more prone to observation error (e.g., false-positive detections) than are sampling approaches utilizing physical captures or sightings of individuals. We conducted realistic, replicated field experiments using a remote broadcasting system to simulate simple anuran call surveys and to investigate potential factors affecting observation error in these studies. Distance, time, ambient noise, and observer abilities were the most important factors explaining false-negative detections. Distance and observer ability were the best overall predictors of false-positive errors, but ambient noise and competing species also affected error rates for some species. False-positive errors made up 5 of all positive detections, with individual observers exhibiting false-positive rates between 0.5 and 14. Previous research suggests false-positive errors of these magnitudes would induce substantial positive biases in standard estimators of species occurrence, and we recommend practices to mitigate for false positives when developing occupancy monitoring protocols that rely on auditory detections. These recommendations include additional observer training, limiting the number of target species, and establishing distance and ambient noise thresholds during surveys. ?? 2010 The Wildlife Society.

Error analysis of the crystal orientations obtained by the dictionary approach to EBSD indexing.

PubMed

Ram, Farangis; Wright, Stuart; Singh, Saransh; De Graef, Marc

2017-10-01

The efficacy of the dictionary approach to Electron Back-Scatter Diffraction (EBSD) indexing was evaluated through the analysis of the error in the retrieved crystal orientations. EBSPs simulated by the Callahan-De Graef forward model were used for this purpose. Patterns were noised, distorted, and binned prior to dictionary indexing. Patterns with a high level of noise, with optical distortions, and with a 25 × 25 pixel size, when the error in projection center was 0.7% of the pattern width and the error in specimen tilt was 0.8°, were indexed with a 0.8° mean error in orientation. The same patterns, but 60 × 60 pixel in size, were indexed by the standard 2D Hough transform based approach with almost the same orientation accuracy. Optimal detection parameters in the Hough space were obtained by minimizing the orientation error. It was shown that if the error in detector geometry can be reduced to 0.1% in projection center and 0.1° in specimen tilt, the dictionary approach can retrieve a crystal orientation with a 0.2° accuracy. Copyright © 2017 Elsevier B.V. All rights reserved.

Profile of refractive errors in cerebral palsy: impact of severity of motor impairment (GMFCS) and CP subtype on refractive outcome.

PubMed

Saunders, Kathryn J; Little, Julie-Anne; McClelland, Julie F; Jackson, A Jonathan

2010-06-01

To describe refractive status in children and young adults with cerebral palsy (CP) and relate refractive error to standardized measures of type and severity of CP impairment and to ocular dimensions. A population-based sample of 118 participants aged 4 to 23 years with CP (mean 11.64 +/- 4.06) and an age-appropriate control group (n = 128; age, 4-16 years; mean, 9.33 +/- 3.52) were recruited. Motor impairment was described with the Gross Motor Function Classification Scale (GMFCS), and subtype was allocated with the Surveillance of Cerebral Palsy in Europe (SCPE). Measures of refractive error were obtained from all participants and ocular biometry from a subgroup with CP. A significantly higher prevalence and magnitude of refractive error was found in the CP group compared to the control group. Axial length and spherical refractive error were strongly related. This relation did not improve with inclusion of corneal data. There was no relation between the presence or magnitude of spherical refractive errors in CP and the level of motor impairment, intellectual impairment, or the presence of communication difficulties. Higher spherical refractive errors were significantly associated with the nonspastic CP subtype. The presence and magnitude of astigmatism were greater when intellectual impairment was more severe, and astigmatic errors were explained by corneal dimensions. Conclusions. High refractive errors are common in CP, pointing to impairment of the emmetropization process. Biometric data support this In contrast to other functional vision measures, spherical refractive error is unrelated to CP severity, but those with nonspastic CP tend to demonstrate the most extreme errors in refraction.

Cost effectiveness of a pharmacist-led information technology intervention for reducing rates of clinically important errors in medicines management in general practices (PINCER).

PubMed

Elliott, Rachel A; Putman, Koen D; Franklin, Matthew; Annemans, Lieven; Verhaeghe, Nick; Eden, Martin; Hayre, Jasdeep; Rodgers, Sarah; Sheikh, Aziz; Avery, Anthony J

2014-06-01

We recently showed that a pharmacist-led information technology-based intervention (PINCER) was significantly more effective in reducing medication errors in general practices than providing simple feedback on errors, with cost per error avoided at £79 (US$131). We aimed to estimate cost effectiveness of the PINCER intervention by combining effectiveness in error reduction and intervention costs with the effect of the individual errors on patient outcomes and healthcare costs, to estimate the effect on costs and QALYs. We developed Markov models for each of six medication errors targeted by PINCER. Clinical event probability, treatment pathway, resource use and costs were extracted from literature and costing tariffs. A composite probabilistic model combined patient-level error models with practice-level error rates and intervention costs from the trial. Cost per extra QALY and cost-effectiveness acceptability curves were generated from the perspective of NHS England, with a 5-year time horizon. The PINCER intervention generated £2,679 less cost and 0.81 more QALYs per practice [incremental cost-effectiveness ratio (ICER): -£3,037 per QALY] in the deterministic analysis. In the probabilistic analysis, PINCER generated 0.001 extra QALYs per practice compared with simple feedback, at £4.20 less per practice. Despite this extremely small set of differences in costs and outcomes, PINCER dominated simple feedback with a mean ICER of -£3,936 (standard error £2,970). At a ceiling 'willingness-to-pay' of £20,000/QALY, PINCER reaches 59 % probability of being cost effective. PINCER produced marginal health gain at slightly reduced overall cost. Results are uncertain due to the poor quality of data to inform the effect of avoiding errors.

Estimating Climatological Bias Errors for the Global Precipitation Climatology Project (GPCP)

NASA Technical Reports Server (NTRS)

Adler, Robert; Gu, Guojun; Huffman, George

2012-01-01

A procedure is described to estimate bias errors for mean precipitation by using multiple estimates from different algorithms, satellite sources, and merged products. The Global Precipitation Climatology Project (GPCP) monthly product is used as a base precipitation estimate, with other input products included when they are within +/- 50% of the GPCP estimates on a zonal-mean basis (ocean and land separately). The standard deviation s of the included products is then taken to be the estimated systematic, or bias, error. The results allow one to examine monthly climatologies and the annual climatology, producing maps of estimated bias errors, zonal-mean errors, and estimated errors over large areas such as ocean and land for both the tropics and the globe. For ocean areas, where there is the largest question as to absolute magnitude of precipitation, the analysis shows spatial variations in the estimated bias errors, indicating areas where one should have more or less confidence in the mean precipitation estimates. In the tropics, relative bias error estimates (s/m, where m is the mean precipitation) over the eastern Pacific Ocean are as large as 20%, as compared with 10%-15% in the western Pacific part of the ITCZ. An examination of latitudinal differences over ocean clearly shows an increase in estimated bias error at higher latitudes, reaching up to 50%. Over land, the error estimates also locate regions of potential problems in the tropics and larger cold-season errors at high latitudes that are due to snow. An empirical technique to area average the gridded errors (s) is described that allows one to make error estimates for arbitrary areas and for the tropics and the globe (land and ocean separately, and combined). Over the tropics this calculation leads to a relative error estimate for tropical land and ocean combined of 7%, which is considered to be an upper bound because of the lack of sign-of-the-error canceling when integrating over different areas with a different number of input products. For the globe the calculated relative error estimate from this study is about 9%, which is also probably a slight overestimate. These tropical and global estimated bias errors provide one estimate of the current state of knowledge of the planet's mean precipitation.

A practical method to test the validity of the standard Gumbel distribution in logit-based multinomial choice models of travel behavior

DOE PAGES

Ye, Xin; Garikapati, Venu M.; You, Daehyun; ...

2017-11-08

Most multinomial choice models (e.g., the multinomial logit model) adopted in practice assume an extreme-value Gumbel distribution for the random components (error terms) of utility functions. This distributional assumption offers a closed-form likelihood expression when the utility maximization principle is applied to model choice behaviors. As a result, model coefficients can be easily estimated using the standard maximum likelihood estimation method. However, maximum likelihood estimators are consistent and efficient only if distributional assumptions on the random error terms are valid. It is therefore critical to test the validity of underlying distributional assumptions on the error terms that form the basismore » of parameter estimation and policy evaluation. In this paper, a practical yet statistically rigorous method is proposed to test the validity of the distributional assumption on the random components of utility functions in both the multinomial logit (MNL) model and multiple discrete-continuous extreme value (MDCEV) model. Based on a semi-nonparametric approach, a closed-form likelihood function that nests the MNL or MDCEV model being tested is derived. The proposed method allows traditional likelihood ratio tests to be used to test violations of the standard Gumbel distribution assumption. Simulation experiments are conducted to demonstrate that the proposed test yields acceptable Type-I and Type-II error probabilities at commonly available sample sizes. The test is then applied to three real-world discrete and discrete-continuous choice models. For all three models, the proposed test rejects the validity of the standard Gumbel distribution in most utility functions, calling for the development of robust choice models that overcome adverse effects of violations of distributional assumptions on the error terms in random utility functions.« less

A practical method to test the validity of the standard Gumbel distribution in logit-based multinomial choice models of travel behavior

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ye, Xin; Garikapati, Venu M.; You, Daehyun

Most multinomial choice models (e.g., the multinomial logit model) adopted in practice assume an extreme-value Gumbel distribution for the random components (error terms) of utility functions. This distributional assumption offers a closed-form likelihood expression when the utility maximization principle is applied to model choice behaviors. As a result, model coefficients can be easily estimated using the standard maximum likelihood estimation method. However, maximum likelihood estimators are consistent and efficient only if distributional assumptions on the random error terms are valid. It is therefore critical to test the validity of underlying distributional assumptions on the error terms that form the basismore » of parameter estimation and policy evaluation. In this paper, a practical yet statistically rigorous method is proposed to test the validity of the distributional assumption on the random components of utility functions in both the multinomial logit (MNL) model and multiple discrete-continuous extreme value (MDCEV) model. Based on a semi-nonparametric approach, a closed-form likelihood function that nests the MNL or MDCEV model being tested is derived. The proposed method allows traditional likelihood ratio tests to be used to test violations of the standard Gumbel distribution assumption. Simulation experiments are conducted to demonstrate that the proposed test yields acceptable Type-I and Type-II error probabilities at commonly available sample sizes. The test is then applied to three real-world discrete and discrete-continuous choice models. For all three models, the proposed test rejects the validity of the standard Gumbel distribution in most utility functions, calling for the development of robust choice models that overcome adverse effects of violations of distributional assumptions on the error terms in random utility functions.« less

Does a better model yield a better argument? An info-gap analysis

NASA Astrophysics Data System (ADS)

Ben-Haim, Yakov

2017-04-01

Theories, models and computations underlie reasoned argumentation in many areas. The possibility of error in these arguments, though of low probability, may be highly significant when the argument is used in predicting the probability of rare high-consequence events. This implies that the choice of a theory, model or computational method for predicting rare high-consequence events must account for the probability of error in these components. However, error may result from lack of knowledge or surprises of various sorts, and predicting the probability of error is highly uncertain. We show that the putatively best, most innovative and sophisticated argument may not actually have the lowest probability of error. Innovative arguments may entail greater uncertainty than more standard but less sophisticated methods, creating an innovation dilemma in formulating the argument. We employ info-gap decision theory to characterize and support the resolution of this problem and present several examples.

Two States Mapping Based Time Series Neural Network Model for Compensation Prediction Residual Error

NASA Astrophysics Data System (ADS)

Jung, Insung; Koo, Lockjo; Wang, Gi-Nam

2008-11-01

The objective of this paper was to design a model of human bio signal data prediction system for decreasing of prediction error using two states mapping based time series neural network BP (back-propagation) model. Normally, a lot of the industry has been applied neural network model by training them in a supervised manner with the error back-propagation algorithm for time series prediction systems. However, it still has got a residual error between real value and prediction result. Therefore, we designed two states of neural network model for compensation residual error which is possible to use in the prevention of sudden death and metabolic syndrome disease such as hypertension disease and obesity. We determined that most of the simulation cases were satisfied by the two states mapping based time series prediction model. In particular, small sample size of times series were more accurate than the standard MLP model.

Measurement Error and Environmental Epidemiology: A Policy Perspective

PubMed Central

Edwards, Jessie K.; Keil, Alexander P.

2017-01-01

Purpose of review Measurement error threatens public health by producing bias in estimates of the population impact of environmental exposures. Quantitative methods to account for measurement bias can improve public health decision making. Recent findings We summarize traditional and emerging methods to improve inference under a standard perspective, in which the investigator estimates an exposure response function, and a policy perspective, in which the investigator directly estimates population impact of a proposed intervention. Summary Under a policy perspective, the analysis must be sensitive to errors in measurement of factors that modify the effect of exposure on outcome, must consider whether policies operate on the true or measured exposures, and may increasingly need to account for potentially dependent measurement error of two or more exposures affected by the same policy or intervention. Incorporating approaches to account for measurement error into such a policy perspective will increase the impact of environmental epidemiology. PMID:28138941

Increased errors and decreased performance at night: A systematic review of the evidence concerning shift work and quality.

PubMed

de Cordova, Pamela B; Bradford, Michelle A; Stone, Patricia W

2016-02-15

Shift workers have worse health outcomes than employees who work standard business hours. However, it is unclear how this poorer health shift may be related to employee work productivity. The purpose of this systematic review is to assess the relationship between shift work and errors and performance. Searches of MEDLINE/PubMed, EBSCOhost, and CINAHL were conducted to identify articles that examined the relationship between shift work, errors, quality, productivity, and performance. All articles were assessed for study quality. A total of 435 abstracts were screened with 13 meeting inclusion criteria. Eight studies were rated to be of strong, methodological quality. Nine studies demonstrated a positive relationship that night shift workers committed more errors and had decreased performance. Night shift workers have worse health that may contribute to errors and decreased performance in the workplace.

Dissipative quantum error correction and application to quantum sensing with trapped ions.

PubMed

Reiter, F; Sørensen, A S; Zoller, P; Muschik, C A

2017-11-28

Quantum-enhanced measurements hold the promise to improve high-precision sensing ranging from the definition of time standards to the determination of fundamental constants of nature. However, quantum sensors lose their sensitivity in the presence of noise. To protect them, the use of quantum error-correcting codes has been proposed. Trapped ions are an excellent technological platform for both quantum sensing and quantum error correction. Here we present a quantum error correction scheme that harnesses dissipation to stabilize a trapped-ion qubit. In our approach, always-on couplings to an engineered environment protect the qubit against spin-flips or phase-flips. Our dissipative error correction scheme operates in a continuous manner without the need to perform measurements or feedback operations. We show that the resulting enhanced coherence time translates into a significantly enhanced precision for quantum measurements. Our work constitutes a stepping stone towards the paradigm of self-correcting quantum information processing.

The impact of statistical adjustment on conditional standard errors of measurement in the assessment of physician communication skills.

PubMed

Raymond, Mark R; Clauser, Brian E; Furman, Gail E

2010-10-01

The use of standardized patients to assess communication skills is now an essential part of assessing a physician's readiness for practice. To improve the reliability of communication scores, it has become increasingly common in recent years to use statistical models to adjust ratings provided by standardized patients. This study employed ordinary least squares regression to adjust ratings, and then used generalizability theory to evaluate the impact of these adjustments on score reliability and the overall standard error of measurement. In addition, conditional standard errors of measurement were computed for both observed and adjusted scores to determine whether the improvements in measurement precision were uniform across the score distribution. Results indicated that measurement was generally less precise for communication ratings toward the lower end of the score distribution; and the improvement in measurement precision afforded by statistical modeling varied slightly across the score distribution such that the most improvement occurred in the upper-middle range of the score scale. Possible reasons for these patterns in measurement precision are discussed, as are the limitations of the statistical models used for adjusting performance ratings.

Probabilities of Occurrence of Baro-Fuze System Errors More Than 1000 Feet Too Low Due to Ignoring the Meteorological Forecast

DOE Office of Scientific and Technical Information (OSTI.GOV)

Charles, B.N.

1955-05-12

Charts of the geographical distribution of the annual and seasonal D-values and their standard deviations at altitudes of 4500, 6000, and 7000 feeet over Eurasia are derived, which are used to estimate the frequency of baro system errors.

Textbook Error: Short Circuiting on Electrochemical Cell

ERIC Educational Resources Information Center

Bonicamp, Judith M.; Clark, Roy W.

2007-01-01

Short circuiting an electrochemical cell is an unreported but persistent error in the electrochemistry textbooks. It is suggested that diagrams depicting a cell delivering usable current to a load be postponed, the theory of open-circuit galvanic cells is explained, the voltages from the tables of standard reduction potentials is calculated and…

Testing Intelligently Includes Double-Checking Wechsler IQ Scores

ERIC Educational Resources Information Center

Kuentzel, Jeffrey G.; Hetterscheidt, Lesley A.; Barnett, Douglas

2011-01-01

The rigors of standardized testing make for numerous opportunities for examiner error, including simple computational mistakes in scoring. Although experts recommend that test scoring be double-checked, the extent to which independent double-checking would reduce scoring errors is not known. A double-checking procedure was established at a…

Monitoring and reporting of preanalytical errors in laboratory medicine: the UK situation.

PubMed

Cornes, Michael P; Atherton, Jennifer; Pourmahram, Ghazaleh; Borthwick, Hazel; Kyle, Betty; West, Jamie; Costelloe, Seán J

2016-03-01

Most errors in the clinical laboratory occur in the preanalytical phase. This study aimed to comprehensively describe the prevalence and nature of preanalytical quality monitoring practices in UK clinical laboratories. A survey was sent on behalf of the Association for Clinical Biochemistry and Laboratory Medicine Preanalytical Working Group (ACB-WG-PA) to all heads of department of clinical laboratories in the UK. The survey captured data on the analytical platform and Laboratory Information Management System in use; which preanalytical errors were recorded and how they were classified and gauged interest in an external quality assurance scheme for preanalytical errors. Of the 157 laboratories asked to participate, responses were received from 104 (66.2%). Laboratory error rates were recorded per number of specimens, rather than per number of requests in 51% of respondents. Aside from serum indices for haemolysis, icterus and lipaemia, which were measured in 80% of laboratories, the most common errors recorded were booking-in errors (70.1%) and sample mislabelling (56.9%) in laboratories who record preanalytical errors. Of the laboratories surveyed, 95.9% expressed an interest in guidance on recording preanalytical error and 91.8% expressed interest in an external quality assurance scheme. This survey observes a wide variation in the definition, repertoire and collection methods for preanalytical errors in the UK. Data indicate there is a lot of interest in improving preanalytical data collection. The ACB-WG-PA aims to produce guidance and support for laboratories to standardize preanalytical data collection and to help establish and validate an external quality assurance scheme for interlaboratory comparison. © The Author(s) 2015.

Can binary early warning scores perform as well as standard early warning scores for discriminating a patient's risk of cardiac arrest, death or unanticipated intensive care unit admission?

PubMed

Jarvis, Stuart; Kovacs, Caroline; Briggs, Jim; Meredith, Paul; Schmidt, Paul E; Featherstone, Peter I; Prytherch, David R; Smith, Gary B

2015-08-01

Although the weightings to be summed in an early warning score (EWS) calculation are small, calculation and other errors occur frequently, potentially impacting on hospital efficiency and patient care. Use of a simpler EWS has the potential to reduce errors. We truncated 36 published 'standard' EWSs so that, for each component, only two scores were possible: 0 when the standard EWS scored 0 and 1 when the standard EWS scored greater than 0. Using 1564,153 vital signs observation sets from 68,576 patient care episodes, we compared the discrimination (measured using the area under the receiver operator characteristic curve--AUROC) of each standard EWS and its truncated 'binary' equivalent. The binary EWSs had lower AUROCs than the standard EWSs in most cases, although for some the difference was not significant. One system, the binary form of the National Early Warning System (NEWS), had significantly better discrimination than all standard EWSs, except for NEWS. Overall, Binary NEWS at a trigger value of 3 would detect as many adverse outcomes as are detected by NEWS using a trigger of 5, but would require a 15% higher triggering rate. The performance of Binary NEWS is only exceeded by that of standard NEWS. It may be that Binary NEWS, as a simplified system, can be used with fewer errors. However, its introduction could lead to significant increases in workload for ward and rapid response team staff. The balance between fewer errors and a potentially greater workload needs further investigation. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Comparison of base flows to selected streamflow statistics representative of 1930-2002 in West Virginia

USGS Publications Warehouse

Wiley, Jeffrey B.

2012-01-01

Base flows were compared with published streamflow statistics to assess climate variability and to determine the published statistics that can be substituted for annual and seasonal base flows of unregulated streams in West Virginia. The comparison study was done by the U.S. Geological Survey, in cooperation with the West Virginia Department of Environmental Protection, Division of Water and Waste Management. The seasons were defined as winter (January 1-March 31), spring (April 1-June 30), summer (July 1-September 30), and fall (October 1-December 31). Differences in mean annual base flows for five record sub-periods (1930-42, 1943-62, 1963-69, 1970-79, and 1980-2002) range from -14.9 to 14.6 percent when compared to the values for the period 1930-2002. Differences between mean seasonal base flows and values for the period 1930-2002 are less variable for winter and spring, -11.2 to 11.0 percent, than for summer and fall, -47.0 to 43.6 percent. Mean summer base flows (July-September) and mean monthly base flows for July, August, September, and October are approximately equal, within 7.4 percentage points of mean annual base flow. The mean of each of annual, spring, summer, fall, and winter base flows are approximately equal to the annual 50-percent (standard error of 10.3 percent), 45-percent (error of 14.6 percent), 75-percent (error of 11.8 percent), 55-percent (error of 11.2 percent), and 35-percent duration flows (error of 11.1 percent), respectively. The mean seasonal base flows for spring, summer, fall, and winter are approximately equal to the spring 50- to 55-percent (standard error of 6.8 percent), summer 45- to 50-percent (error of 6.7 percent), fall 45-percent (error of 15.2 percent), and winter 60-percent duration flows (error of 8.5 percent), respectively. Annual and seasonal base flows representative of the period 1930-2002 at unregulated streamflow-gaging stations and ungaged locations in West Virginia can be estimated using previously published values of statistics and procedures.

Calibration of low-temperature ac susceptometers with a copper cylinder standard

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, D.-X.; Skumryev, V.

2010-02-15

A high-quality low-temperature ac susceptometer is calibrated by comparing the measured ac susceptibility of a copper cylinder with its eddy-current ac susceptibility accurately calculated. Different from conventional calibration techniques that compare the measured results with the known property of a standard sample at certain fixed temperature T, field amplitude H{sub m}, and frequency f, to get a magnitude correction factor, here, the electromagnetic properties of the copper cylinder are unknown and are determined during the calibration of the ac susceptometer in the entire T, H{sub m}, and f range. It is shown that the maximum magnitude error and the maximummore » phase error of the susceptometer are less than 0.7% and 0.3 deg., respectively, in the region T=5-300 K and f=111-1111 Hz at H{sub m}=800 A/m, after a magnitude correction by a constant factor as done in a conventional calibration. However, the magnitude and phase errors can reach 2% and 4.3 deg. at 10 000 and 11 Hz, respectively. Since the errors are reproducible, a large portion of them may be further corrected after a calibration, the procedure for which is given. Conceptual discussions concerning the error sources, comparison with other calibration methods, and applications of ac susceptibility techniques are presented.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Olama, Mohammed M; Matalgah, Mustafa M; Bobrek, Miljko

Traditional encryption techniques require packet overhead, produce processing time delay, and suffer from severe quality of service deterioration due to fades and interference in wireless channels. These issues reduce the effective transmission data rate (throughput) considerably in wireless communications, where data rate with limited bandwidth is the main constraint. In this paper, performance evaluation analyses are conducted for an integrated signaling-encryption mechanism that is secure and enables improved throughput and probability of bit-error in wireless channels. This mechanism eliminates the drawbacks stated herein by encrypting only a small portion of an entire transmitted frame, while the rest is not subjectmore » to traditional encryption but goes through a signaling process (designed transformation) with the plaintext of the portion selected for encryption. We also propose to incorporate error correction coding solely on the small encrypted portion of the data to drastically improve the overall bit-error rate performance while not noticeably increasing the required bit-rate. We focus on validating the signaling-encryption mechanism utilizing Hamming and convolutional error correction coding by conducting an end-to-end system-level simulation-based study. The average probability of bit-error and throughput of the encryption mechanism are evaluated over standard Gaussian and Rayleigh fading-type channels and compared to the ones of the conventional advanced encryption standard (AES).« less

Accuracy of a Radiological Evaluation Method for Thoracic and Lumbar Spinal Curvatures Using Spinous Processes.

PubMed

Marchetti, Bárbara V; Candotti, Cláudia T; Raupp, Eduardo G; Oliveira, Eduardo B C; Furlanetto, Tássia S; Loss, Jefferson F

The purpose of this study was to assess a radiographic method for spinal curvature evaluation in children, based on spinous processes, and identify its normality limits. The sample consisted of 90 radiographic examinations of the spines of children in the sagittal plane. Thoracic and lumbar curvatures were evaluated using angular (apex angle [AA]) and linear (sagittal arrow [SA]) measurements based on the spinous processes. The same curvatures were also evaluated using the Cobb angle (CA) method, which is considered the gold standard. For concurrent validity (AA vs CA), Pearson's product-moment correlation coefficient, root-mean-square error, Pitman- Morgan test, and Bland-Altman analysis were used. For reproducibility (AA, SA, and CA), the intraclass correlation coefficient, standard error of measurement, and minimal detectable change measurements were used. A significant correlation was found between CA and AA measurements, as was a low root-mean-square error. The mean difference between the measurements was 0° for thoracic and lumbar curvatures, and the mean standard deviations of the differences were ±5.9° and 6.9°, respectively. The intraclass correlation coefficients of AA and SA were similar to or higher than the gold standard (CA). The standard error of measurement and minimal detectable change of the AA were always lower than the CA. This study determined the concurrent validity, as well as intra- and interrater reproducibility, of the radiographic measurements of kyphosis and lordosis in children. Copyright © 2017. Published by Elsevier Inc.

An Empirical State Error Covariance Matrix Orbit Determination Example

NASA Technical Reports Server (NTRS)

Frisbee, Joseph H., Jr.

2015-01-01

State estimation techniques serve effectively to provide mean state estimates. However, the state error covariance matrices provided as part of these techniques suffer from some degree of lack of confidence in their ability to adequately describe the uncertainty in the estimated states. A specific problem with the traditional form of state error covariance matrices is that they represent only a mapping of the assumed observation error characteristics into the state space. Any errors that arise from other sources (environment modeling, precision, etc.) are not directly represented in a traditional, theoretical state error covariance matrix. First, consider that an actual observation contains only measurement error and that an estimated observation contains all other errors, known and unknown. Then it follows that a measurement residual (the difference between expected and observed measurements) contains all errors for that measurement. Therefore, a direct and appropriate inclusion of the actual measurement residuals in the state error covariance matrix of the estimate will result in an empirical state error covariance matrix. This empirical state error covariance matrix will fully include all of the errors in the state estimate. The empirical error covariance matrix is determined from a literal reinterpretation of the equations involved in the weighted least squares estimation algorithm. It is a formally correct, empirical state error covariance matrix obtained through use of the average form of the weighted measurement residual variance performance index rather than the usual total weighted residual form. Based on its formulation, this matrix will contain the total uncertainty in the state estimate, regardless as to the source of the uncertainty and whether the source is anticipated or not. It is expected that the empirical error covariance matrix will give a better, statistical representation of the state error in poorly modeled systems or when sensor performance is suspect. In its most straight forward form, the technique only requires supplemental calculations to be added to existing batch estimation algorithms. In the current problem being studied a truth model making use of gravity with spherical, J2 and J4 terms plus a standard exponential type atmosphere with simple diurnal and random walk components is used. The ability of the empirical state error covariance matrix to account for errors is investigated under four scenarios during orbit estimation. These scenarios are: exact modeling under known measurement errors, exact modeling under corrupted measurement errors, inexact modeling under known measurement errors, and inexact modeling under corrupted measurement errors. For this problem a simple analog of a distributed space surveillance network is used. The sensors in this network make only range measurements and with simple normally distributed measurement errors. The sensors are assumed to have full horizon to horizon viewing at any azimuth. For definiteness, an orbit at the approximate altitude and inclination of the International Space Station is used for the study. The comparison analyses of the data involve only total vectors. No investigation of specific orbital elements is undertaken. The total vector analyses will look at the chisquare values of the error in the difference between the estimated state and the true modeled state using both the empirical and theoretical error covariance matrices for each of scenario.

Literacy, Numeracy, and Problem Solving in Technology-Rich Environments among U.S. Adults: Results from the Program for the International Assessment of Adult Competencies 2012. Appendix D: Standard Error Tables. First Look. NCES 2014-008

ERIC Educational Resources Information Center

National Center for Education Statistics, 2013

2013-01-01

This paper provides Appendix D, Standard Error tables, for the full report, entitled. "Literacy, Numeracy, and Problem Solving in Technology-Rich Environments among U.S. Adults: Results from the Program for the International Assessment of Adult Competencies 2012. First Look. NCES 2014-008." The full report presents results of the Program…

Static Scene Statistical Non-Uniformity Correction

DTIC Science & Technology

2015-03-01

Error NUC Non-Uniformity Correction RMSE Root Mean Squared Error RSD Relative Standard Deviation S3NUC Static Scene Statistical Non-Uniformity...Deviation ( RSD ) which normalizes the standard deviation, σ, to the mean estimated value, µ using the equation RS D = σ µ × 100. The RSD plot of the gain...estimates is shown in Figure 4.1(b). The RSD plot shows that after a sample size of approximately 10, the different photocount values and the inclusion

Evaluation of alternative model selection criteria in the analysis of unimodal response curves using CART

USGS Publications Warehouse

Ribic, C.A.; Miller, T.W.

1998-01-01

We investigated CART performance with a unimodal response curve for one continuous response and four continuous explanatory variables, where two variables were important (ie directly related to the response) and the other two were not. We explored performance under three relationship strengths and two explanatory variable conditions: equal importance and one variable four times as important as the other. We compared CART variable selection performance using three tree-selection rules ('minimum risk', 'minimum risk complexity', 'one standard error') to stepwise polynomial ordinary least squares (OLS) under four sample size conditions. The one-standard-error and minimum-risk-complexity methods performed about as well as stepwise OLS with large sample sizes when the relationship was strong. With weaker relationships, equally important explanatory variables and larger sample sizes, the one-standard-error and minimum-risk-complexity rules performed better than stepwise OLS. With weaker relationships and explanatory variables of unequal importance, tree-structured methods did not perform as well as stepwise OLS. Comparing performance within tree-structured methods, with a strong relationship and equally important explanatory variables, the one-standard-error-rule was more likely to choose the correct model than were the other tree-selection rules 1) with weaker relationships and equally important explanatory variables; and 2) under all relationship strengths when explanatory variables were of unequal importance and sample sizes were lower.

Reliability of anthropometric measurements in European preschool children: the ToyBox-study.

PubMed

De Miguel-Etayo, P; Mesana, M I; Cardon, G; De Bourdeaudhuij, I; Góźdź, M; Socha, P; Lateva, M; Iotova, V; Koletzko, B V; Duvinage, K; Androutsos, O; Manios, Y; Moreno, L A

2014-08-01

The ToyBox-study aims to develop and test an innovative and evidence-based obesity prevention programme for preschoolers in six European countries: Belgium, Bulgaria, Germany, Greece, Poland and Spain. In multicentre studies, anthropometric measurements using standardized procedures that minimize errors in the data collection are essential to maximize reliability of measurements. The aim of this paper is to describe the standardization process and reliability (intra- and inter-observer) of height, weight and waist circumference (WC) measurements in preschoolers. All technical procedures and devices were standardized and centralized training was given to the fieldworkers. At least seven children per country participated in the intra- and inter-observer reliability testing. Intra-observer technical error ranged from 0.00 to 0.03 kg for weight and from 0.07 to 0.20 cm for height, with the overall reliability being above 99%. A second training was organized for WC due to low reliability observed in the first training. Intra-observer technical error for WC ranged from 0.12 to 0.71 cm during the first training and from 0.05 to 1.11 cm during the second training, and reliability above 92% was achieved. Epidemiological surveys need standardized procedures and training of researchers to reduce measurement error. In the ToyBox-study, very good intra- and-inter-observer agreement was achieved for all anthropometric measurements performed. © 2014 World Obesity.

Estimates and Standard Errors for Ratios of Normalizing Constants from Multiple Markov Chains via Regeneration

PubMed Central

Doss, Hani; Tan, Aixin

2017-01-01

In the classical biased sampling problem, we have k densities π1(·), …, πk(·), each known up to a normalizing constant, i.e. for l = 1, …, k, πl(·) = νl(·)/ml, where νl(·) is a known function and ml is an unknown constant. For each l, we have an iid sample from πl,·and the problem is to estimate the ratios ml/ms for all l and all s. This problem arises frequently in several situations in both frequentist and Bayesian inference. An estimate of the ratios was developed and studied by Vardi and his co-workers over two decades ago, and there has been much subsequent work on this problem from many different perspectives. In spite of this, there are no rigorous results in the literature on how to estimate the standard error of the estimate. We present a class of estimates of the ratios of normalizing constants that are appropriate for the case where the samples from the πl’s are not necessarily iid sequences, but are Markov chains. We also develop an approach based on regenerative simulation for obtaining standard errors for the estimates of ratios of normalizing constants. These standard error estimates are valid for both the iid case and the Markov chain case. PMID:28706463

Estimates and Standard Errors for Ratios of Normalizing Constants from Multiple Markov Chains via Regeneration.

PubMed

Doss, Hani; Tan, Aixin

2014-09-01

In the classical biased sampling problem, we have k densities π 1 (·), …, π k (·), each known up to a normalizing constant, i.e. for l = 1, …, k , π l (·) = ν l (·)/ m l , where ν l (·) is a known function and m l is an unknown constant. For each l , we have an iid sample from π l , · and the problem is to estimate the ratios m l /m s for all l and all s . This problem arises frequently in several situations in both frequentist and Bayesian inference. An estimate of the ratios was developed and studied by Vardi and his co-workers over two decades ago, and there has been much subsequent work on this problem from many different perspectives. In spite of this, there are no rigorous results in the literature on how to estimate the standard error of the estimate. We present a class of estimates of the ratios of normalizing constants that are appropriate for the case where the samples from the π l 's are not necessarily iid sequences, but are Markov chains. We also develop an approach based on regenerative simulation for obtaining standard errors for the estimates of ratios of normalizing constants. These standard error estimates are valid for both the iid case and the Markov chain case.

High IQ May "Mask" the Diagnosis of ADHD by Compensating for Deficits in Executive Functions in Treatment-Naïve Adults With ADHD.

PubMed

Milioni, Ana Luiza Vidal; Chaim, Tiffany Moukbel; Cavallet, Mikael; de Oliveira, Nathalya Moleda; Annes, Marco; Dos Santos, Bernardo; Louzã, Mario; da Silva, Maria Aparecida; Miguel, Carmen Silvia; Serpa, Mauricio Henriques; Zanetti, Marcus V; Busatto, Geraldo; Cunha, Paulo Jannuzzi

2017-04-01

To evaluate and compare the performance of adults with ADHD with high and standard IQ in executive functions (EF) tasks. We investigated the neuropsychological performance of 51 adults with ADHD, compared with 33 healthy controls (HC) while performing a wide battery of neuropsychological tests that measure executive functioning. Adults with clinical diagnosis of ADHD were divided into two groups according to their IQ level (IQ ≥ 110-ADHD group with more elevated IQ, and IQ < 110-ADHD group with standard IQ). The ADHD group with standard IQ presented a worse executive functioning compared with the HC group in the following measures: Stroop 2 ( p = .000) and 3 ( p = .000), Trail Making Test (TMT) B ( p = .005), Wisconsin Card-Sorting Test (WCST)-perseverative errors ( p = .022) and failures to maintain set ( p = .020), Continuous Performance Test (CPT)-omission errors ( p = .005) and commission errors ( p = .000), and Frontal Assessment Battery (FAB)-conceptualization ( p = .016). The ADHD group with more elevated IQ presented only impairments in the CPT-commission errors ( p = .019) when compared with the control group. Adults with ADHD and more elevated IQ show less evidence of executive functioning deficits compared with those with ADHD and standard IQ, suggesting that a higher degree of intellectual efficiency may compensate deficits in executive functions, leading to problems in establishing a precise clinical diagnosis.

A fast Monte Carlo EM algorithm for estimation in latent class model analysis with an application to assess diagnostic accuracy for cervical neoplasia in women with AGC

PubMed Central

Kang, Le; Carter, Randy; Darcy, Kathleen; Kauderer, James; Liao, Shu-Yuan

2013-01-01

In this article we use a latent class model (LCM) with prevalence modeled as a function of covariates to assess diagnostic test accuracy in situations where the true disease status is not observed, but observations on three or more conditionally independent diagnostic tests are available. A fast Monte Carlo EM (MCEM) algorithm with binary (disease) diagnostic data is implemented to estimate parameters of interest; namely, sensitivity, specificity, and prevalence of the disease as a function of covariates. To obtain standard errors for confidence interval construction of estimated parameters, the missing information principle is applied to adjust information matrix estimates. We compare the adjusted information matrix based standard error estimates with the bootstrap standard error estimates both obtained using the fast MCEM algorithm through an extensive Monte Carlo study. Simulation demonstrates that the adjusted information matrix approach estimates the standard error similarly with the bootstrap methods under certain scenarios. The bootstrap percentile intervals have satisfactory coverage probabilities. We then apply the LCM analysis to a real data set of 122 subjects from a Gynecologic Oncology Group (GOG) study of significant cervical lesion (S-CL) diagnosis in women with atypical glandular cells of undetermined significance (AGC) to compare the diagnostic accuracy of a histology-based evaluation, a CA-IX biomarker-based test and a human papillomavirus (HPV) DNA test. PMID:24163493

Medication errors: problems and recommendations from a consensus meeting

PubMed Central

Agrawal, Abha; Aronson, Jeffrey K; Britten, Nicky; Ferner, Robin E; de Smet, Peter A; Fialová, Daniela; Fitzgerald, Richard J; Likić, Robert; Maxwell, Simon R; Meyboom, Ronald H; Minuz, Pietro; Onder, Graziano; Schachter, Michael; Velo, Giampaolo

2009-01-01

Here we discuss 15 recommendations for reducing the risks of medication errors: Provision of sufficient undergraduate learning opportunities to make medical students safe prescribers. Provision of opportunities for students to practise skills that help to reduce errors. Education of students about common types of medication errors and how to avoid them. Education of prescribers in taking accurate drug histories. Assessment in medical schools of prescribing knowledge and skills and demonstration that newly qualified doctors are safe prescribers. European harmonization of prescribing and safety recommendations and regulatory measures, with regular feedback about rational drug use. Comprehensive assessment of elderly patients for declining function. Exploration of low-dose regimens for elderly patients and preparation of special formulations as required. Training for all health-care professionals in drug use, adverse effects, and medication errors in elderly people. More involvement of pharmacists in clinical practice. Introduction of integrated prescription forms and national implementation in individual countries. Development of better monitoring systems for detecting medication errors, based on classification and analysis of spontaneous reports of previous reactions, and for investigating the possible role of medication errors when patients die. Use of IT systems, when available, to provide methods of avoiding medication errors; standardization, proper evaluation, and certification of clinical information systems. Nonjudgmental communication with patients about their concerns and elicitation of symptoms that they perceive to be adverse drug reactions. Avoidance of defensive reactions if patients mention symptoms resulting from medication errors. PMID:19594525

Evaluation of causes and frequency of medication errors during information technology downtime.

PubMed

Hanuscak, Tara L; Szeinbach, Sheryl L; Seoane-Vazquez, Enrique; Reichert, Brendan J; McCluskey, Charles F

2009-06-15

The causes and frequency of medication errors occurring during information technology downtime were evaluated. Individuals from a convenience sample of 78 hospitals who were directly responsible for supporting and maintaining clinical information systems (CISs) and automated dispensing systems (ADSs) were surveyed using an online tool between February 2007 and May 2007 to determine if medication errors were reported during periods of system downtime. The errors were classified using the National Coordinating Council for Medication Error Reporting and Prevention severity scoring index. The percentage of respondents reporting downtime was estimated. Of the 78 eligible hospitals, 32 respondents with CIS and ADS responsibilities completed the online survey for a response rate of 41%. For computerized prescriber order entry, patch installations and system upgrades caused an average downtime of 57% over a 12-month period. Lost interface and interface malfunction were reported for centralized and decentralized ADSs, with an average downtime response of 34% and 29%, respectively. The average downtime response was 31% for software malfunctions linked to clinical decision-support systems. Although patient harm did not result from 30 (54%) medication errors, the potential for harm was present for 9 (16%) of these errors. Medication errors occurred during CIS and ADS downtime despite the availability of backup systems and standard protocols to handle periods of system downtime. Efforts should be directed to reduce the frequency and length of down-time in order to minimize medication errors during such downtime.

Influence of survey strategy and interpolation model on DEM quality

NASA Astrophysics Data System (ADS)

Heritage, George L.; Milan, David J.; Large, Andrew R. G.; Fuller, Ian C.

2009-11-01

Accurate characterisation of morphology is critical to many studies in the field of geomorphology, particularly those dealing with changes over time. Digital elevation models (DEMs) are commonly used to represent morphology in three dimensions. The quality of the DEM is largely a function of the accuracy of individual survey points, field survey strategy, and the method of interpolation. Recommendations concerning field survey strategy and appropriate methods of interpolation are currently lacking. Furthermore, the majority of studies to date consider error to be uniform across a surface. This study quantifies survey strategy and interpolation error for a gravel bar on the River Nent, Blagill, Cumbria, UK. Five sampling strategies were compared: (i) cross section; (ii) bar outline only; (iii) bar and chute outline; (iv) bar and chute outline with spot heights; and (v) aerial LiDAR equivalent, derived from degraded terrestrial laser scan (TLS) data. Digital Elevation Models were then produced using five different common interpolation algorithms. Each resultant DEM was differentiated from a terrestrial laser scan of the gravel bar surface in order to define the spatial distribution of vertical and volumetric error. Overall triangulation with linear interpolation (TIN) or point kriging appeared to provide the best interpolators for the bar surface. Lowest error on average was found for the simulated aerial LiDAR survey strategy, regardless of interpolation technique. However, comparably low errors were also found for the bar-chute-spot sampling strategy when TINs or point kriging was used as the interpolator. The magnitude of the errors between survey strategy exceeded those found between interpolation technique for a specific survey strategy. Strong relationships between local surface topographic variation (as defined by the standard deviation of vertical elevations in a 0.2-m diameter moving window), and DEM errors were also found, with much greater errors found at slope breaks such as bank edges. A series of curves are presented that demonstrate these relationships for each interpolation and survey strategy. The simulated aerial LiDAR data set displayed the lowest errors across the flatter surfaces; however, sharp slope breaks are better modelled by the morphologically based survey strategy. The curves presented have general application to spatially distributed data of river beds and may be applied to standard deviation grids to predict spatial error within a surface, depending upon sampling strategy and interpolation algorithm.

Phase-demodulation error of a fiber-optic Fabry-Perot sensor with complex reflection coefficients.

PubMed

Kilpatrick, J M; MacPherson, W N; Barton, J S; Jones, J D

2000-03-20

The influence of reflector losses attracts little discussion in standard treatments of the Fabry-Perot interferometer yet may be an important factor contributing to errors in phase-stepped demodulation of fiber optic Fabry-Perot (FFP) sensors. We describe a general transfer function for FFP sensors with complex reflection coefficients and estimate systematic phase errors that arise when the asymmetry of the reflected fringe system is neglected, as is common in the literature. The measured asymmetric response of higher-finesse metal-dielectric FFP constructions corroborates a model that predicts systematic phase errors of 0.06 rad in three-step demodulation of a low-finesse FFP sensor (R = 0.05) with internal reflector losses of 25%.

Analytic aerotriangulation utilizing Skylab earth terrain camera (S-190B) photography. [from Charlotte, North Carolina to Rappahannock River in Virginia

NASA Technical Reports Server (NTRS)

Keller, M. (Principal Investigator)

1975-01-01

The author has identified the following significant results. Inherent errors in using nonmetric Skylab photography and office-identified photo control made it necessary to perform numerous block adjustment solutions involving different combinations of control and weights. The final block adjustment was executed holding to 14 of the office-identified photo control points. Solution accuracy was evaluated by comparing the analytically computed ground positions of the withheld photo control points with their known ground positions and also by determining the standard errors of these points from variance values. A horizontal position RMS error of 15 meters was attained. The maximum observed error in position at a control point was 25 meters.

Sinusoidal Siemens star spatial frequency response measurement errors due to misidentified target centers

DOE PAGES

Birch, Gabriel Carisle; Griffin, John Clark

2015-07-23

Numerous methods are available to measure the spatial frequency response (SFR) of an optical system. A recent change to the ISO 12233 photography resolution standard includes a sinusoidal Siemens star test target. We take the sinusoidal Siemens star proposed by the ISO 12233 standard, measure system SFR, and perform an analysis of errors induced by incorrectly identifying the center of a test target. We show a closed-form solution for the radial profile intensity measurement given an incorrectly determined center and describe how this error reduces the measured SFR of the system. As a result, using the closed-form solution, we proposemore » a two-step process by which test target centers are corrected and the measured SFR is restored to the nominal, correctly centered values.« less

Linewidth-tolerant 10-Gbit/s 16-QAM transmission using a pilot-carrier based phase-noise cancelling technique.

PubMed

Nakamura, Moriya; Kamio, Yukiyoshi; Miyazaki, Tetsuya

2008-07-07

We experimentally demonstrated linewidth-tolerant 10-Gbit/s (2.5-Gsymbol/s) 16-quadrature amplitude modulation (QAM) by using a distributed-feedback laser diode (DFB-LD) with a linewidth of 30 MHz. Error-free operation, a bit-error rate (BER) of <10(-9) was achieved in transmission over 120 km of standard single mode fiber (SSMF) without any dispersion compensation. The phase-noise canceling capability provided by a pilot-carrier and standard electronic pre-equalization to suppress inter-symbol interference (ISI) gave clear 16-QAM constellations and floor-less BER characteristics. We evaluated the BER characteristics by real-time measurement of six (three different thresholds for each I- and Q-component) symbol error rates (SERs) with simultaneous constellation observation.

Adiabatic gate teleportation.

PubMed

Bacon, Dave; Flammia, Steven T

2009-09-18

The difficulty in producing precisely timed and controlled quantum gates is a significant source of error in many physical implementations of quantum computers. Here we introduce a simple universal primitive, adiabatic gate teleportation, which is robust to timing errors and many control errors and maintains a constant energy gap throughout the computation above a degenerate ground state space. This construction allows for geometric robustness based upon the control of two independent qubit interactions. Further, our piecewise adiabatic evolution easily relates to the quantum circuit model, enabling the use of standard methods from fault-tolerance theory for establishing thresholds.

Human error and the search for blame

NASA Technical Reports Server (NTRS)

Denning, Peter J.

1989-01-01

Human error is a frequent topic in discussions about risks in using computer systems. A rational analysis of human error leads through the consideration of mistakes to standards that designers use to avoid mistakes that lead to known breakdowns. The irrational side, however, is more interesting. It conditions people to think that breakdowns are inherently wrong and that there is ultimately someone who is responsible. This leads to a search for someone to blame which diverts attention from: learning from the mistakes; seeing the limitations of current engineering methodology; and improving the discourse of design.

Helical gears with circular arc teeth: Generation, geometry, precision and adjustment to errors, computer aided simulation of conditions of meshing and bearing contact

NASA Technical Reports Server (NTRS)

Litvin, Faydor L.; Tsay, Chung-Biau

1987-01-01

The authors have proposed a method for the generation of circular arc helical gears which is based on the application of standard equipment, worked out all aspects of the geometry of the gears, proposed methods for the computer aided simulation of conditions of meshing and bearing contact, investigated the influence of manufacturing and assembly errors, and proposed methods for the adjustment of gears to these errors. The results of computer aided solutions are illustrated with computer graphics.

Cache-based error recovery for shared memory multiprocessor systems

NASA Technical Reports Server (NTRS)

Wu, Kun-Lung; Fuchs, W. Kent; Patel, Janak H.

1989-01-01

A multiprocessor cache-based checkpointing and recovery scheme for of recovering from transient processor errors in a shared-memory multiprocessor with private caches is presented. New implementation techniques that use checkpoint identifiers and recovery stacks to reduce performance degradation in processor utilization during normal execution are examined. This cache-based checkpointing technique prevents rollback propagation, provides for rapid recovery, and can be integrated into standard cache coherence protocols. An analytical model is used to estimate the relative performance of the scheme during normal execution. Extensions that take error latency into account are presented.

WE-A-17A-03: Catheter Digitization in High-Dose-Rate Brachytherapy with the Assistance of An Electromagnetic (EM) Tracking System

DOE Office of Scientific and Technical Information (OSTI.GOV)

Damato, AL; Bhagwat, MS; Buzurovic, I

Purpose: To investigate the use of a system using EM tracking, postprocessing and error-detection algorithms for measuring brachytherapy catheter locations and for detecting errors and resolving uncertainties in treatment-planning catheter digitization. Methods: An EM tracker was used to localize 13 catheters in a clinical surface applicator (A) and 15 catheters inserted into a phantom (B). Two pairs of catheters in (B) crossed paths at a distance <2 mm, producing an undistinguishable catheter artifact in that location. EM data was post-processed for noise reduction and reformatted to provide the dwell location configuration. CT-based digitization was automatically extracted from the brachytherapy planmore » DICOM files (CT). EM dwell digitization error was characterized in terms of the average and maximum distance between corresponding EM and CT dwells per catheter. The error detection rate (detected errors / all errors) was calculated for 3 types of errors: swap of two catheter numbers; incorrect catheter number identification superior to the closest position between two catheters (mix); and catheter-tip shift. Results: The averages ± 1 standard deviation of the average and maximum registration error per catheter were 1.9±0.7 mm and 3.0±1.1 mm for (A) and 1.6±0.6 mm and 2.7±0.8 mm for (B). The error detection rate was 100% (A and B) for swap errors, mix errors, and shift >4.5 mm (A) and >5.5 mm (B); errors were detected for shifts on average >2.0 mm (A) and >2.4 mm (B). Both mix errors associated with undistinguishable catheter artifacts were detected and at least one of the involved catheters was identified. Conclusion: We demonstrated the use of an EM tracking system for localization of brachytherapy catheters, detection of digitization errors and resolution of undistinguishable catheter artifacts. Automatic digitization may be possible with a registration between the imaging and the EM frame of reference. Research funded by the Kaye Family Award 2012.« less

The precision of a special purpose analog computer in clinical cardiac output determination.

PubMed Central

Sullivan, F J; Mroz, E A; Miller, R E

1975-01-01

Three hundred dye-dilution curves taken during our first year of clinical experience with the Waters CO-4 cardiac output computer were analyzed to estimate the errors involved in its use. Provided that calibration is accurate and 5.0 mg of dye are injected for each curve, then the percentage standard deviation of measurement using this computer is about 8.7%. Included in this are the errors inherent in the computer, errors due to baseline drift, errors in the injection of dye and acutal variation of cardiac output over a series of successive determinations. The size of this error is comparable to that involved in manual calculation. The mean value of five successive curves will be within 10% of the real value in 99 cases out of 100. Advances in methodology and equipment are discussed which make calibration simpler and more accurate, and which should also improve the quality of computer determination. A list of suggestions is given to minimize the errors involved in the clinical use of this equipment. Images Fig. 4. PMID:1089394

Object permanence in adult common marmosets (Callithrix jacchus): not everything is an "A-not-B" error that seems to be one.

PubMed

Kis, Anna; Gácsi, Márta; Range, Friederike; Virányi, Zsófia

2012-01-01

In this paper, we describe a behaviour pattern similar to the "A-not-B" error found in human infants and young apes in a monkey species, the common marmosets (Callithrix jacchus). In contrast to the classical explanation, recently it has been suggested that the "A-not-B" error committed by human infants is at least partially due to misinterpretation of the hider's ostensively communicated object hiding actions as potential 'teaching' demonstrations during the A trials. We tested whether this so-called Natural Pedagogy hypothesis would account for the A-not-B error that marmosets commit in a standard object permanence task, but found no support for the hypothesis in this species. Alternatively, we present evidence that lower level mechanisms, such as attention and motivation, play an important role in committing the "A-not-B" error in marmosets. We argue that these simple mechanisms might contribute to the effect of undeveloped object representational skills in other species including young non-human primates that commit the A-not-B error.

Flavour and identification threshold detection overview of Slovak adepts for certified testing.

PubMed

Vietoris, VladimIr; Barborova, Petra; Jancovicova, Jana; Eliasova, Lucia; Karvaj, Marian

2016-07-01

During certification process of sensory assessors of Slovak certification body we obtained results for basic taste thresholds and lifestyle habits. 500 adult people were screened during experiment with food industry background. For analysis of basic and non basic tastes, we used standardized procedure of ISO 8586-1:1993. In flavour test experiment, group of (26-35 y.o) produced the lowest error ratio (1.438), highest is (56+ y.o.) group with result (2.0). Average error value based on gender for women was (1.510) in comparison to men (1.477). People with allergies have the average error ratio (1.437) in comparison to people without allergies (1.511). Non-smokers produced less errors (1.484) against the smokers (1.576). Another flavour threshold identification test detected differences among age groups (by age are values increased). The highest number of errors made by men in metallic taste was (24%) the same as made by women (22%). Higher error ratio made by men occurred in salty taste (19%) against women (10%). Analysis detected some differences between allergic/non-allergic, smokers/non-smokers groups.

A Practical Methodology for Quantifying Random and Systematic Components of Unexplained Variance in a Wind Tunnel

NASA Technical Reports Server (NTRS)

Deloach, Richard; Obara, Clifford J.; Goodman, Wesley L.

2012-01-01

This paper documents a check standard wind tunnel test conducted in the Langley 0.3-Meter Transonic Cryogenic Tunnel (0.3M TCT) that was designed and analyzed using the Modern Design of Experiments (MDOE). The test designed to partition the unexplained variance of typical wind tunnel data samples into two constituent components, one attributable to ordinary random error, and one attributable to systematic error induced by covariate effects. Covariate effects in wind tunnel testing are discussed, with examples. The impact of systematic (non-random) unexplained variance on the statistical independence of sequential measurements is reviewed. The corresponding correlation among experimental errors is discussed, as is the impact of such correlation on experimental results generally. The specific experiment documented herein was organized as a formal test for the presence of unexplained variance in representative samples of wind tunnel data, in order to quantify the frequency with which such systematic error was detected, and its magnitude relative to ordinary random error. Levels of systematic and random error reported here are representative of those quantified in other facilities, as cited in the references.

Multipollutant measurement error in air pollution epidemiology studies arising from predicting exposures with penalized regression splines

PubMed Central

Bergen, Silas; Sheppard, Lianne; Kaufman, Joel D.; Szpiro, Adam A.

2016-01-01

Summary Air pollution epidemiology studies are trending towards a multi-pollutant approach. In these studies, exposures at subject locations are unobserved and must be predicted using observed exposures at misaligned monitoring locations. This induces measurement error, which can bias the estimated health effects and affect standard error estimates. We characterize this measurement error and develop an analytic bias correction when using penalized regression splines to predict exposure. Our simulations show bias from multi-pollutant measurement error can be severe, and in opposite directions or simultaneously positive or negative. Our analytic bias correction combined with a non-parametric bootstrap yields accurate coverage of 95% confidence intervals. We apply our methodology to analyze the association of systolic blood pressure with PM2.5 and NO2 in the NIEHS Sister Study. We find that NO2 confounds the association of systolic blood pressure with PM2.5 and vice versa. Elevated systolic blood pressure was significantly associated with increased PM2.5 and decreased NO2. Correcting for measurement error bias strengthened these associations and widened 95% confidence intervals. PMID:27789915

Modeling and Control of a Tailsitter with a Ducted Fan

NASA Astrophysics Data System (ADS)

Argyle, Matthew Elliott

There are two traditional aircraft categories: fixed-wing which have a long endurance and a high cruise airspeed and rotorcraft which can take-off and land vertically. The tailsitter is a type of aircraft that has the strengths of both platforms, with no additional mechanical complexity, because it takes off and lands vertically on its tail and can transition the entire aircraft horizontally into high-speed flight. In this dissertation, we develop the entire control system for a tailsitter with a ducted fan. The standard method to compute the quaternion-based attitude error does not generate ideal trajectories for a hovering tailsitter for some situations. In addition, the only approach in the literature to mitigate this breaks down for large attitude errors. We develop an alternative quaternion-based error method which generates better trajectories than the standard approach and can handle large errors. We also derive a hybrid backstepping controller with almost global asymptotic stability based on this error method. Many common altitude and airspeed control schemes for a fixed-wing airplane assume that the altitude and airspeed dynamics are decoupled which leads to errors. The Total Energy Control System (TECS) is an approach that controls the altitude and airspeed by manipulating the total energy rate and energy distribution rate, of the aircraft, in a manner which accounts for the dynamic coupling. In this dissertation, a nonlinear controller, which can handle inaccurate thrust and drag models, based on the TECS principles is derived. Simulation results show that the nonlinear controller has better performance than the standard PI TECS control schemes. Most constant altitude transitions are accomplished by generating an optimal trajectory, and potentially actuator inputs, based on a high fidelity model of the aircraft. While there are several approaches to mitigate the effects of modeling errors, these do not fully remove the accurate model requirement. In this dissertation, we develop two different approaches that can achieve near constant altitude transitions for some types of aircraft. The first method, based on multiple LQR controllers, requires a high fidelity model of the aircraft. However, the second method, based on the energy along the body axes, requires almost no aerodynamic information.

Integrity modelling of tropospheric delay models

NASA Astrophysics Data System (ADS)

Rózsa, Szabolcs; Bastiaan Ober, Pieter; Mile, Máté; Ambrus, Bence; Juni, Ildikó

2017-04-01

The effect of the neutral atmosphere on signal propagation is routinely estimated by various tropospheric delay models in satellite navigation. Although numerous studies can be found in the literature investigating the accuracy of these models, for safety-of-life applications it is crucial to study and model the worst case performance of these models using very low recurrence frequencies. The main objective of the INTegrity of TROpospheric models (INTRO) project funded by the ESA PECS programme is to establish a model (or models) of the residual error of existing tropospheric delay models for safety-of-life applications. Such models are required to overbound rare tropospheric delays and should thus include the tails of the error distributions. Their use should lead to safe error bounds on the user position and should allow computation of protection levels for the horizontal and vertical position errors. The current tropospheric model from the RTCA SBAS Minimal Operational Standards has an associated residual error that equals 0.12 meters in the vertical direction. This value is derived by simply extrapolating the observed distribution of the residuals into the tail (where no data is present) and then taking the point where the cumulative distribution has an exceedance level would be 10-7.While the resulting standard deviation is much higher than the estimated standard variance that best fits the data (0.05 meters), it surely is conservative for most applications. In the context of the INTRO project some widely used and newly developed tropospheric delay models (e.g. RTCA MOPS, ESA GALTROPO and GPT2W) were tested using 16 years of daily ERA-INTERIM Reanalysis numerical weather model data and the raytracing technique. The results showed that the performance of some of the widely applied models have a clear seasonal dependency and it is also affected by a geographical position. In order to provide a more realistic, but still conservative estimation of the residual error of tropospheric delays, the mathematical formulation of the overbounding models are currently under development. This study introduces the main findings of the residual error analysis of the studied tropospheric delay models, and discusses the preliminary analysis of the integrity model development for safety-of-life applications.

A novel artificial fish swarm algorithm for recalibration of fiber optic gyroscope error parameters.

PubMed

Gao, Yanbin; Guan, Lianwu; Wang, Tingjun; Sun, Yunlong

2015-05-05

The artificial fish swarm algorithm (AFSA) is one of the state-of-the-art swarm intelligent techniques, which is widely utilized for optimization purposes. Fiber optic gyroscope (FOG) error parameters such as scale factors, biases and misalignment errors are relatively unstable, especially with the environmental disturbances and the aging of fiber coils. These uncalibrated error parameters are the main reasons that the precision of FOG-based strapdown inertial navigation system (SINS) degraded. This research is mainly on the application of a novel artificial fish swarm algorithm (NAFSA) on FOG error coefficients recalibration/identification. First, the NAFSA avoided the demerits (e.g., lack of using artificial fishes' pervious experiences, lack of existing balance between exploration and exploitation, and high computational cost) of the standard AFSA during the optimization process. To solve these weak points, functional behaviors and the overall procedures of AFSA have been improved with some parameters eliminated and several supplementary parameters added. Second, a hybrid FOG error coefficients recalibration algorithm has been proposed based on NAFSA and Monte Carlo simulation (MCS) approaches. This combination leads to maximum utilization of the involved approaches for FOG error coefficients recalibration. After that, the NAFSA is verified with simulation and experiments and its priorities are compared with that of the conventional calibration method and optimal AFSA. Results demonstrate high efficiency of the NAFSA on FOG error coefficients recalibration.

Prevention of medication errors: detection and audit.

PubMed

Montesi, Germana; Lechi, Alessandro

2009-06-01

1. Medication errors have important implications for patient safety, and their identification is a main target in improving clinical practice errors, in order to prevent adverse events. 2. Error detection is the first crucial step. Approaches to this are likely to be different in research and routine care, and the most suitable must be chosen according to the setting. 3. The major methods for detecting medication errors and associated adverse drug-related events are chart review, computerized monitoring, administrative databases, and claims data, using direct observation, incident reporting, and patient monitoring. All of these methods have both advantages and limitations. 4. Reporting discloses medication errors, can trigger warnings, and encourages the diffusion of a culture of safe practice. Combining and comparing data from various and encourages the diffusion of a culture of safe practice sources increases the reliability of the system. 5. Error prevention can be planned by means of retroactive and proactive tools, such as audit and Failure Mode, Effect, and Criticality Analysis (FMECA). Audit is also an educational activity, which promotes high-quality care; it should be carried out regularly. In an audit cycle we can compare what is actually done against reference standards and put in place corrective actions to improve the performances of individuals and systems. 6. Patient safety must be the first aim in every setting, in order to build safer systems, learning from errors and reducing the human and fiscal costs.

Integration of Error Compensation of Coordinate Measuring Machines into Feature Measurement: Part I—Model Development

PubMed Central

Calvo, Roque; D’Amato, Roberto; Gómez, Emilio; Domingo, Rosario

2016-01-01

The development of an error compensation model for coordinate measuring machines (CMMs) and its integration into feature measurement is presented. CMMs are widespread and dependable instruments in industry and laboratories for dimensional measurement. From the tip probe sensor to the machine display, there is a complex transformation of probed point coordinates through the geometrical feature model that makes the assessment of accuracy and uncertainty measurement results difficult. Therefore, error compensation is not standardized, conversely to other simpler instruments. Detailed coordinate error compensation models are generally based on CMM as a rigid-body and it requires a detailed mapping of the CMM’s behavior. In this paper a new model type of error compensation is proposed. It evaluates the error from the vectorial composition of length error by axis and its integration into the geometrical measurement model. The non-explained variability by the model is incorporated into the uncertainty budget. Model parameters are analyzed and linked to the geometrical errors and uncertainty of CMM response. Next, the outstanding measurement models of flatness, angle, and roundness are developed. The proposed models are useful for measurement improvement with easy integration into CMM signal processing, in particular in industrial environments where built-in solutions are sought. A battery of implementation tests are presented in Part II, where the experimental endorsement of the model is included. PMID:27690052

Testing the effect of computer-generated hologram fabrication error in a cylindrical interferometry system

NASA Astrophysics Data System (ADS)

Wang, Qingquan; Yu, Yingjie; Mou, Kebing

2017-10-01

This paper presents a method of testing the effect of computer-generated hologram (CGH) fabrication error in a cylindrical interferometry system. An experimental system is developed for calibrating the effect of this error. In the calibrating system, a mirror with high surface accuracy is placed at the focal axis of the cylindrical wave. After transmitting through the CGH, the reflected cylindrical wave can be transformed into a plane wave again, and then the plane wave interferes with the reference plane wave. Finally, the double-pass transmitted wavefront of the CGH, representing the effect of the CGH fabrication error in the experimental system, is obtained by analyzing the interferogram. The mathematical model of misalignment aberration removal in the calibration system is described, and the feasibility is demonstrated via the simulation system established in Zemax. With the mathematical polynomial, most of the possible misalignment errors can be estimated with the least-squares fitting algorithm, and then the double-pass transmitted wavefront of the CGH can be obtained by subtracting the misalignment errors from the result extracted from the real experimental system. Compared to the standard double-pass transmitted wavefront given by Diffraction International Ltd., which manufactured the CGH used in the experimental system, the result is desirable. We conclude that the proposed method is effective in calibrating the effect of the CGH error in the cylindrical interferometry system for the measurement of cylindricity error.

Applying lessons from social psychology to transform the culture of error disclosure.

PubMed

Han, Jason; LaMarra, Denise; Vapiwala, Neha

2017-10-01

The ability to carry out prompt and effective error disclosure has been described in the literature as an essential skill among physicians that can lead to improved patient satisfaction, staff well-being and hospital outcomes. However, few studies have addressed the social psychology principles that may influence physician behaviour. The authors provide an overview of recent administrative measures designed to encourage physicians to disclose error, but note that deliberate practice, buttressed with lessons from social psychology, is needed to implement further productive behavioural changes. Two main cognitive biases that may hinder error disclosure are identified, namely: fundamental attribution error, and forecasting error. Strategies to overcome these maladaptive cognitive patterns are discussed. The authors note that interactions with standardised patients (SPs) can be used to simulate hospital encounters and help teach important behavioural considerations. Virtual reality is introduced as an immersive, realistic and easily scalable technology that can supplement traditional curricula. Lastly, the authors highlight the importance of establishing a professional standard of competence, potentially by incorporating difficult patient encounters, including disclosure of error, into medical licensing examinations that assess clinical skills. Existing curricula that cover physician error disclosure may benefit from reviewing the social psychology literature. These lessons, incorporated into SP programmes and emerging technological platforms, may improve training and evaluative methods for all medical trainees. © 2017 John Wiley & Sons Ltd and The Association for the Study of Medical Education.

Type I error rates of rare single nucleotide variants are inflated in tests of association with non-normally distributed traits using simple linear regression methods.

PubMed

Schwantes-An, Tae-Hwi; Sung, Heejong; Sabourin, Jeremy A; Justice, Cristina M; Sorant, Alexa J M; Wilson, Alexander F

2016-01-01

In this study, the effects of (a) the minor allele frequency of the single nucleotide variant (SNV), (b) the degree of departure from normality of the trait, and (c) the position of the SNVs on type I error rates were investigated in the Genetic Analysis Workshop (GAW) 19 whole exome sequence data. To test the distribution of the type I error rate, 5 simulated traits were considered: standard normal and gamma distributed traits; 2 transformed versions of the gamma trait (log 10 and rank-based inverse normal transformations); and trait Q1 provided by GAW 19. Each trait was tested with 313,340 SNVs. Tests of association were performed with simple linear regression and average type I error rates were determined for minor allele frequency classes. Rare SNVs (minor allele frequency < 0.05) showed inflated type I error rates for non-normally distributed traits that increased as the minor allele frequency decreased. The inflation of average type I error rates increased as the significance threshold decreased. Normally distributed traits did not show inflated type I error rates with respect to the minor allele frequency for rare SNVs. There was no consistent effect of transformation on the uniformity of the distribution of the location of SNVs with a type I error.

Increased instrument intelligence--can it reduce laboratory error?

PubMed

Jekelis, Albert W

2005-01-01

Recent literature has focused on the reduction of laboratory errors and the potential impact on patient management. This study assessed the intelligent, automated preanalytical process-control abilities in newer generation analyzers as compared with older analyzers and the impact on error reduction. Three generations of immuno-chemistry analyzers were challenged with pooled human serum samples for a 3-week period. One of the three analyzers had an intelligent process of fluidics checks, including bubble detection. Bubbles can cause erroneous results due to incomplete sample aspiration. This variable was chosen because it is the most easily controlled sample defect that can be introduced. Traditionally, lab technicians have had to visually inspect each sample for the presence of bubbles. This is time consuming and introduces the possibility of human error. Instruments with bubble detection may be able to eliminate the human factor and reduce errors associated with the presence of bubbles. Specific samples were vortexed daily to introduce a visible quantity of bubbles, then immediately placed in the daily run. Errors were defined as a reported result greater than three standard deviations below the mean and associated with incomplete sample aspiration of the analyte of the individual analyzer Three standard deviations represented the target limits of proficiency testing. The results of the assays were examined for accuracy and precision. Efficiency, measured as process throughput, was also measured to associate a cost factor and potential impact of the error detection on the overall process. The analyzer performance stratified according to their level of internal process control The older analyzers without bubble detection reported 23 erred results. The newest analyzer with bubble detection reported one specimen incorrectly. The precision and accuracy of the nonvortexed specimens were excellent and acceptable for all three analyzers. No errors were found in the nonvortexed specimens. There were no significant differences in overall process time for any of the analyzers when tests were arranged in an optimal configuration. The analyzer with advanced fluidic intelligence demostrated the greatest ability to appropriately deal with an incomplete aspiration by not processing and reporting a result for the sample. This study suggests that preanalytical process-control capabilities could reduce errors. By association, it implies that similar intelligent process controls could favorably impact the error rate and, in the case of this instrument, do it without negatively impacting process throughput. Other improvements may be realized as a result of having an intelligent error-detection process including further reduction in misreported results, fewer repeats, less operator intervention, and less reagent waste.

Systematic errors in regional climate model RegCM over Europe and sensitivity to variations in PBL parameterizations

NASA Astrophysics Data System (ADS)

Güttler, I.

2012-04-01

Systematic errors in near-surface temperature (T2m), total cloud cover (CLD), shortwave albedo (ALB) and surface net longwave (SNL) and shortwave energy flux (SNS) are detected in simulations of RegCM on 50 km resolution over the European CORDEX domain when forced with ERA-Interim reanalysis. Simulated T2m is compared to CRU 3.0 and other variables to GEWEX-SRB 3.0 dataset. Most of systematic errors found in SNL and SNS are consistent with errors in T2m, CLD and ALB: they include prevailing negative errors in T2m and positive errors in CLD present during most of the year. Errors in T2m and CLD can be associated with the overestimation of SNL and SNS in most simulations. Impact of errors in albedo are primarily confined to north Africa, where e.g. underestimation of albedo in JJA is consistent with associated surface heating and positive SNS and T2m errors. Sensitivity to the choice of the PBL scheme and various parameters in PBL schemes is examined from an ensemble of 20 simulations. The recently implemented prognostic PBL scheme performs over Europe with a mixed success when compared to standard diagnostic scheme with a general increase of errors in T2m and CLD over all of the domain. Nevertheless, the improvements in T2m can be found in e.g. north-eastern Europe during DJF and western Europe during JJA where substantial warm biases existed in simulations with the diagnostic scheme. The most detectable impact, in terms of the JJA T2m errors over western Europe, comes form the variation in the formulation of mixing length. In order to reduce the above errors an update of the RegCM albedo values and further work in customizing PBL scheme is suggested.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Passarge, M; Fix, M K; Manser, P

Purpose: To create and test an accurate EPID-frame-based VMAT QA metric to detect gross dose errors in real-time and to provide information about the source of error. Methods: A Swiss cheese model was created for an EPID-based real-time QA process. The system compares a treatmentplan- based reference set of EPID images with images acquired over each 2° gantry angle interval. The metric utilizes a sequence of independent consecutively executed error detection Methods: a masking technique that verifies infield radiation delivery and ensures no out-of-field radiation; output normalization checks at two different stages; global image alignment to quantify rotation, scaling andmore » translation; standard gamma evaluation (3%, 3 mm) and pixel intensity deviation checks including and excluding high dose gradient regions. Tolerances for each test were determined. For algorithm testing, twelve different types of errors were selected to modify the original plan. Corresponding predictions for each test case were generated, which included measurement-based noise. Each test case was run multiple times (with different noise per run) to assess the ability to detect introduced errors. Results: Averaged over five test runs, 99.1% of all plan variations that resulted in patient dose errors were detected within 2° and 100% within 4° (∼1% of patient dose delivery). Including cases that led to slightly modified but clinically equivalent plans, 91.5% were detected by the system within 2°. Based on the type of method that detected the error, determination of error sources was achieved. Conclusion: An EPID-based during-treatment error detection system for VMAT deliveries was successfully designed and tested. The system utilizes a sequence of methods to identify and prevent gross treatment delivery errors. The system was inspected for robustness with realistic noise variations, demonstrating that it has the potential to detect a large majority of errors in real-time and indicate the error source. J. V. Siebers receives funding support from Varian Medical Systems.« less

Stratospheric Assimilation of Chemical Tracer Observations Using a Kalman Filter. Pt. 2; Chi-Square Validated Results and Analysis of Variance and Correlation Dynamics

NASA Technical Reports Server (NTRS)

Menard, Richard; Chang, Lang-Ping

1998-01-01

A Kalman filter system designed for the assimilation of limb-sounding observations of stratospheric chemical tracers, which has four tunable covariance parameters, was developed in Part I (Menard et al. 1998) The assimilation results of CH4 observations from the Cryogenic Limb Array Etalon Sounder instrument (CLAES) and the Halogen Observation Experiment instrument (HALOE) on board of the Upper Atmosphere Research Satellite are described in this paper. A robust (chi)(sup 2) criterion, which provides a statistical validation of the forecast and observational error covariances, was used to estimate the tunable variance parameters of the system. In particular, an estimate of the model error variance was obtained. The effect of model error on the forecast error variance became critical after only three days of assimilation of CLAES observations, although it took 14 days of forecast to double the initial error variance. We further found that the model error due to numerical discretization as arising in the standard Kalman filter algorithm, is comparable in size to the physical model error due to wind and transport modeling errors together. Separate assimilations of CLAES and HALOE observations were compared to validate the state estimate away from the observed locations. A wave-breaking event that took place several thousands of kilometers away from the HALOE observation locations was well captured by the Kalman filter due to highly anisotropic forecast error correlations. The forecast error correlation in the assimilation of the CLAES observations was found to have a structure similar to that in pure forecast mode except for smaller length scales. Finally, we have conducted an analysis of the variance and correlation dynamics to determine their relative importance in chemical tracer assimilation problems. Results show that the optimality of a tracer assimilation system depends, for the most part, on having flow-dependent error correlation rather than on evolving the error variance.

SU-E-T-257: Output Constancy: Reducing Measurement Variations in a Large Practice Group

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hedrick, K; Fitzgerald, T; Miller, R

2014-06-01

Purpose: To standardize output constancy check procedures in a large medical physics practice group covering multiple sites, in order to identify and reduce small systematic errors caused by differences in equipment and the procedures of multiple physicists. Methods: A standardized machine output constancy check for both photons and electrons was instituted within the practice group in 2010. After conducting annual TG-51 measurements in water and adjusting the linac to deliver 1.00 cGy/MU at Dmax, an acrylic phantom (comparable at all sites) and PTW farmer ion chamber are used to obtain monthly output constancy reference readings. From the collected charge reading,more » measurements of air pressure and temperature, and chamber Ndw and Pelec, a value we call the Kacrylic factor is determined, relating the chamber reading in acrylic to the dose in water with standard set-up conditions. This procedure easily allows for multiple equipment combinations to be used at any site. The Kacrylic factors and output results from all sites and machines are logged monthly in a central database and used to monitor trends in calibration and output. Results: The practice group consists of 19 sites, currently with 34 Varian and 8 Elekta linacs (24 Varian and 5 Elekta linacs in 2010). Over the past three years, the standard deviation of Kacrylic factors measured on all machines decreased by 20% for photons and high energy electrons as systematic errors were found and reduced. Low energy electrons showed very little change in the distribution of Kacrylic values. Small errors in linac beam data were found by investigating outlier Kacrylic values. Conclusion: While the use of acrylic phantoms introduces an additional source of error through small differences in depth and effective depth, the new standardized procedure eliminates potential sources of error from using many different phantoms and results in more consistent output constancy measurements.« less

Comparative study of standard space and real space analysis of quantitative MR brain data.

PubMed

Aribisala, Benjamin S; He, Jiabao; Blamire, Andrew M

2011-06-01

To compare the robustness of region of interest (ROI) analysis of magnetic resonance imaging (MRI) brain data in real space with analysis in standard space and to test the hypothesis that standard space image analysis introduces more partial volume effect errors compared to analysis of the same dataset in real space. Twenty healthy adults with no history or evidence of neurological diseases were recruited; high-resolution T(1)-weighted, quantitative T(1), and B(0) field-map measurements were collected. Algorithms were implemented to perform analysis in real and standard space and used to apply a simple standard ROI template to quantitative T(1) datasets. Regional relaxation values and histograms for both gray and white matter tissues classes were then extracted and compared. Regional mean T(1) values for both gray and white matter were significantly lower using real space compared to standard space analysis. Additionally, regional T(1) histograms were more compact in real space, with smaller right-sided tails indicating lower partial volume errors compared to standard space analysis. Standard space analysis of quantitative MRI brain data introduces more partial volume effect errors biasing the analysis of quantitative data compared to analysis of the same dataset in real space. Copyright © 2011 Wiley-Liss, Inc.

Optical storage media data integrity studies

NASA Technical Reports Server (NTRS)

Podio, Fernando L.

1994-01-01

Optical disk-based information systems are being used in private industry and many Federal Government agencies for on-line and long-term storage of large quantities of data. The storage devices that are part of these systems are designed with powerful, but not unlimited, media error correction capacities. The integrity of data stored on optical disks does not only depend on the life expectancy specifications for the medium. Different factors, including handling and storage conditions, may result in an increase of medium errors in size and frequency. Monitoring the potential data degradation is crucial, especially for long term applications. Efforts are being made by the Association for Information and Image Management Technical Committee C21, Storage Devices and Applications, to specify methods for monitoring and reporting to the user medium errors detected by the storage device while writing, reading or verifying the data stored in that medium. The Computer Systems Laboratory (CSL) of the National Institute of Standard and Technology (NIST) has a leadership role in the development of these standard techniques. In addition, CSL is researching other data integrity issues, including the investigation of error-resilient compression algorithms. NIST has conducted care and handling experiments on optical disk media with the objective of identifying possible causes of degradation. NIST work in data integrity and related standards activities is described.

Cost effectiveness of the US Geological Survey's stream-gaging programs in New Hampshire and Vermont

USGS Publications Warehouse

Smath, J.A.; Blackey, F.E.

1986-01-01

Data uses and funding sources were identified for the 73 continuous stream gages currently (1984) being operated. Eight stream gages were identified as having insufficient reason to continue their operation. Parts of New Hampshire and Vermont were identified as needing additional hydrologic data. New gages should be established in these regions as funds become available. Alternative methods for providing hydrologic data at the stream gaging stations currently being operated were found to lack the accuracy that is required for their intended use. The current policy for operation of the stream gages requires a net budget of $297,000/yr. The average standard error of estimation of the streamflow records is 17.9%. This overall level of accuracy could be maintained with a budget of $285,000 if resources were redistributed among gages. Cost-effective analysis indicates that with the present budget, the average standard error could be reduced to 16.6%. A minimum budget of $278,000 is required to operate the present stream gaging program. Below this level, the gages and recorders would not receive the proper service and maintenance. At the minimum budget, the average standard error would be 20.4%. The loss of correlative data is a significant component of the error in streamflow records, especially at lower budgetary levels. (Author 's abstract)

47 CFR 1.1167 - Error claims related to regulatory fees.

Code of Federal Regulations, 2010 CFR

2010-10-01

...) Challenges to determinations or an insufficient regulatory fee payment or delinquent fees should be made in writing. A challenge to a determination that a party is delinquent in paying a standard regulatory fee... 47 Telecommunication 1 2010-10-01 2010-10-01 false Error claims related to regulatory fees. 1.1167...

Variability in Pretest-Posttest Correlation Coefficients by Student Achievement Level. NCEE 2011-4033

ERIC Educational Resources Information Center

Cole, Russell; Haimson, Joshua; Perez-Johnson, Irma; May, Henry

2011-01-01

State assessments are increasingly used as outcome measures for education evaluations. The scaling of state assessments produces variability in measurement error, with the conditional standard error of measurement increasing as average student ability moves toward the tails of the achievement distribution. This report examines the variability in…

Estimating the Autocorrelated Error Model with Trended Data: Further Results,

DTIC Science & Technology

1979-11-01

Perhaps the most serious deficiency of OLS in the presence of autocorrelation is not inefficiency but bias in its estimated standard errors--a bias...k for all t has variance var(b) = o2/ Tk2 2This refutes Maeshiro’s (1976) conjecture that "an estimator utilizing relevant extraneous information

Taboo, Constraint, and Responsibility in Educational Research.

ERIC Educational Resources Information Center

Jensen, Arthur R.

A controversial educational researcher lists personal experiences which seem to have ethical implications for his profession. His list includes: (1) a claim that one of his articles contained 53 errors, but after two years, the American Psychological Association (APA) Committee on Ethical Standards had only received a list of 53 non-errors; (2) a…

A Cognitive Approach to Brailling Errors

ERIC Educational Resources Information Center

Wells-Jensen, Sheri; Schwartz, Aaron; Gosche, Bradley

2007-01-01

This article analyzes a corpus of 1,600 brailling errors made by one expert braillist. It presents a testable model of braille writing and shows that the subject braillist stores standard braille contractions as part of the orthographic representation of words, rather than imposing contractions on a serially ordered string of letters. (Contains 1…

Student Distractor Choices on the Mathematics Virginia Standards of Learning Middle School Assessments

ERIC Educational Resources Information Center

Lewis, Virginia Vimpeny

2011-01-01

Number Concepts; Measurement; Geometry; Probability; Statistics; and Patterns, Functions and Algebra. Procedural Errors were further categorized into the following content categories: Computation; Measurement; Statistics; and Patterns, Functions, and Algebra. The results of the analysis showed the main sources of error for 6th, 7th, and 8th…

Quality Control of an OSCE Using Generalizability Theory and Many-Faceted Rasch Measurement

ERIC Educational Resources Information Center

Iramaneerat, Cherdsak; Yudkowsky, Rachel; Myford, Carol M.; Downing, Steven M.

2008-01-01

An Objective Structured Clinical Examination (OSCE) is an effective method for evaluating competencies. However, scores obtained from an OSCE are vulnerable to many potential measurement errors that cases, items, or standardized patients (SPs) can introduce. Monitoring these sources of errors is an important quality control mechanism to ensure…

Computation Error Analysis: Students with Mathematics Difficulty Compared to Typically Achieving Students

ERIC Educational Resources Information Center

Nelson, Gena; Powell, Sarah R.

2018-01-01

Though proficiency with computation is highly emphasized in national mathematics standards, students with mathematics difficulty (MD) continue to struggle with computation. To learn more about the differences in computation error patterns between typically achieving students and students with MD, we assessed 478 third-grade students on a measure…

Optimal estimation of suspended-sediment concentrations in streams

USGS Publications Warehouse

Holtschlag, D.J.

2001-01-01

Optimal estimators are developed for computation of suspended-sediment concentrations in streams. The estimators are a function of parameters, computed by use of generalized least squares, which simultaneously account for effects of streamflow, seasonal variations in average sediment concentrations, a dynamic error component, and the uncertainty in concentration measurements. The parameters are used in a Kalman filter for on-line estimation and an associated smoother for off-line estimation of suspended-sediment concentrations. The accuracies of the optimal estimators are compared with alternative time-averaging interpolators and flow-weighting regression estimators by use of long-term daily-mean suspended-sediment concentration and streamflow data from 10 sites within the United States. For sampling intervals from 3 to 48 days, the standard errors of on-line and off-line optimal estimators ranged from 52.7 to 107%, and from 39.5 to 93.0%, respectively. The corresponding standard errors of linear and cubic-spline interpolators ranged from 48.8 to 158%, and from 50.6 to 176%, respectively. The standard errors of simple and multiple regression estimators, which did not vary with the sampling interval, were 124 and 105%, respectively. Thus, the optimal off-line estimator (Kalman smoother) had the lowest error characteristics of those evaluated. Because suspended-sediment concentrations are typically measured at less than 3-day intervals, use of optimal estimators will likely result in significant improvements in the accuracy of continuous suspended-sediment concentration records. Additional research on the integration of direct suspended-sediment concentration measurements and optimal estimators applied at hourly or shorter intervals is needed.

Smooth Approximation l 0-Norm Constrained Affine Projection Algorithm and Its Applications in Sparse Channel Estimation

PubMed Central

2014-01-01

We propose a smooth approximation l 0-norm constrained affine projection algorithm (SL0-APA) to improve the convergence speed and the steady-state error of affine projection algorithm (APA) for sparse channel estimation. The proposed algorithm ensures improved performance in terms of the convergence speed and the steady-state error via the combination of a smooth approximation l 0-norm (SL0) penalty on the coefficients into the standard APA cost function, which gives rise to a zero attractor that promotes the sparsity of the channel taps in the channel estimation and hence accelerates the convergence speed and reduces the steady-state error when the channel is sparse. The simulation results demonstrate that our proposed SL0-APA is superior to the standard APA and its sparsity-aware algorithms in terms of both the convergence speed and the steady-state behavior in a designated sparse channel. Furthermore, SL0-APA is shown to have smaller steady-state error than the previously proposed sparsity-aware algorithms when the number of nonzero taps in the sparse channel increases. PMID:24790588

Computer-socket manufacturing error: How much before it is clinically apparent?

PubMed Central

Sanders, Joan E.; Severance, Michael R.; Allyn, Kathryn J.

2015-01-01

The purpose of this research was to pursue quality standards for computer-manufacturing of prosthetic sockets for people with transtibial limb loss. Thirty-three duplicates of study participants’ normally used sockets were fabricated using central fabrication facilities. Socket-manufacturing errors were compared with clinical assessments of socket fit. Of the 33 sockets tested, 23 were deemed clinically to need modification. All 13 sockets with mean radial error (MRE) greater than 0.25 mm were clinically unacceptable, and 11 of those were deemed in need of sizing reduction. Of the remaining 20 sockets, 5 sockets with interquartile range (IQR) greater than 0.40 mm were deemed globally or regionally oversized and in need of modification. Of the remaining 15 sockets, 5 sockets with closed contours of elevated surface normal angle error (SNAE) were deemed clinically to need shape modification at those closed contour locations. The remaining 10 sockets were deemed clinically acceptable and not in need modification. MRE, IQR, and SNAE may serve as effective metrics to characterize quality of computer-manufactured prosthetic sockets, helping facilitate the development of quality standards for the socket manufacturing industry. PMID:22773260

ALT space shuttle barometric altimeter altitude analysis

NASA Technical Reports Server (NTRS)

Killen, R.

1978-01-01

The accuracy was analyzed of the barometric altimeters onboard the space shuttle orbiter. Altitude estimates from the air data systems including the operational instrumentation and the developmental flight instrumentation were obtained for each of the approach and landing test flights. By comparing the barometric altitude estimates to altitudes derived from radar tracking data filtered through a Kalman filter and fully corrected for atmospheric refraction, the errors in the barometric altitudes were shown to be 4 to 5 percent of the Kalman altitudes. By comparing the altitude determined from the true atmosphere derived from weather balloon data to the altitude determined from the U.S. Standard Atmosphere of 1962, it was determined that the assumption of the Standard Atmosphere equations contributes roughly 75 percent of the total error in the baro estimates. After correcting the barometric altitude estimates using an average summer model atmosphere computed for the average latitude of the space shuttle landing sites, the residual error in the altitude estimates was reduced to less than 373 feet. This corresponds to an error of less than 1.5 percent for altitudes above 4000 feet for all flights.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bishop, L.; Hill, W.J.

A method is proposed to estimate the effect of long-term variations in total ozone on the error incurred in determining a trend in total ozone due to man-made effects. When this method is applied to data from Arosa, Switzerland over the years 1932--1980, a component of the standard error of the trend estimate equal to 0.6 percent per decade is obtained. If this estimate of long-term trend variability at Arosa is not too different from global long-term trend variability, then the threshold ( +- 2 standard errors) for detecting an ozone trend in the 1970's that is outside of whatmore » could be expected from natural variation alone and hence be man-made would range from 1.35% (Reinsel et al, 1981) to 1.8%. The latter value is obtained by combining the Reinsel et al result with the result here, assuming that the error variations that both studies measure are independent and additive. Estimates for long-term trend variation over other time periods are also derived. Simulations that measure the precision of the estimate of long-term variability are reported.« less

Optimization of the moving-bed biofilm sequencing batch reactor (MBSBR) to control aeration time by kinetic computational modeling: Simulated sugar-industry wastewater treatment.

PubMed

Faridnasr, Maryam; Ghanbari, Bastam; Sassani, Ardavan

2016-05-01

A novel approach was applied for optimization of a moving-bed biofilm sequencing batch reactor (MBSBR) to treat sugar-industry wastewater (BOD5=500-2500 and COD=750-3750 mg/L) at 2-4 h of cycle time (CT). Although the experimental data showed that MBSBR reached high BOD5 and COD removal performances, it failed to achieve the standard limits at the mentioned CTs. Thus, optimization of the reactor was rendered by kinetic computational modeling and using statistical error indicator normalized root mean square error (NRMSE). The results of NRMSE revealed that Stover-Kincannon (error=6.40%) and Grau (error=6.15%) models provide better fits to the experimental data and may be used for CT optimization in the reactor. The models predicted required CTs of 4.5, 6.5, 7 and 7.5 h for effluent standardization of 500, 1000, 1500 and 2500 mg/L influent BOD5 concentrations, respectively. Similar pattern of the experimental data also confirmed these findings. Copyright © 2016 Elsevier Ltd. All rights reserved.

A parallel row-based algorithm with error control for standard-cell replacement on a hypercube multiprocessor

NASA Technical Reports Server (NTRS)

Sargent, Jeff Scott

1988-01-01

A new row-based parallel algorithm for standard-cell placement targeted for execution on a hypercube multiprocessor is presented. Key features of this implementation include a dynamic simulated-annealing schedule, row-partitioning of the VLSI chip image, and two novel new approaches to controlling error in parallel cell-placement algorithms; Heuristic Cell-Coloring and Adaptive (Parallel Move) Sequence Control. Heuristic Cell-Coloring identifies sets of noninteracting cells that can be moved repeatedly, and in parallel, with no buildup of error in the placement cost. Adaptive Sequence Control allows multiple parallel cell moves to take place between global cell-position updates. This feedback mechanism is based on an error bound derived analytically from the traditional annealing move-acceptance profile. Placement results are presented for real industry circuits and the performance is summarized of an implementation on the Intel iPSC/2 Hypercube. The runtime of this algorithm is 5 to 16 times faster than a previous program developed for the Hypercube, while producing equivalent quality placement. An integrated place and route program for the Intel iPSC/2 Hypercube is currently being developed.

Monte Carlo simulation of errors in the anisotropy of magnetic susceptibility - A second-rank symmetric tensor. [for grains in sedimentary and volcanic rocks

NASA Technical Reports Server (NTRS)

Lienert, Barry R.

1991-01-01

Monte Carlo perturbations of synthetic tensors to evaluate the Hext/Jelinek elliptical confidence regions for anisotropy of magnetic susceptibility (AMS) eigenvectors are used. When the perturbations are 33 percent of the minimum anisotropy, both the shapes and probability densities of the resulting eigenvector distributions agree with the elliptical distributions predicted by the Hext/Jelinek equations. When the perturbation size is increased to 100 percent of the minimum eigenvalue difference, the major axis of the 95 percent confidence ellipse underestimates the observed eigenvector dispersion by about 10 deg. The observed distributions of the principal susceptibilities (eigenvalues) are close to being normal, with standard errors that agree well with the calculated Hext/Jelinek errors. The Hext/Jelinek ellipses are also able to describe the AMS dispersions due to instrumental noise and provide reasonable limits for the AMS dispersions observed in two Hawaiian basaltic dikes. It is concluded that the Hext/Jelinek method provides a satisfactory description of the errors in AMS data and should be a standard part of any AMS data analysis.

Effects of Tropospheric Spatio-Temporal Correlated Noise on the Analysis of Space Geodetic Data

NASA Technical Reports Server (NTRS)

Romero-Wolf, A.; Jacobs, C. S.; Ratcliff, J. T.

2012-01-01

The standard VLBI analysis models the distribution of measurement noise as Gaussian. Because the price of recording bits is steadily decreasing, thermal errors will soon no longer dominate. As a result, it is expected that troposphere and instrumentation/clock errors will increasingly become more dominant. Given that both of these errors have correlated spectra, properly modeling the error distributions will become increasingly relevant for optimal analysis. We discuss the advantages of modeling the correlations between tropospheric delays using a Kolmogorov spectrum and the frozen flow assumption pioneered by Treuhaft and Lanyi. We then apply these correlated noise spectra to the weighting of VLBI data analysis for two case studies: X/Ka-band global astrometry and Earth orientation. In both cases we see improved results when the analyses are weighted with correlated noise models vs. the standard uncorrelated models. The X/Ka astrometric scatter improved by approx.10% and the systematic Delta delta vs. delta slope decreased by approx. 50%. The TEMPO Earth orientation results improved by 17% in baseline transverse and 27% in baseline vertical.

Evaluation of Natural Language Processing (NLP) Systems to Annotate Drug Product Labeling with MedDRA Terminology.

PubMed

Ly, Thomas; Pamer, Carol; Dang, Oanh; Brajovic, Sonja; Haider, Shahrukh; Botsis, Taxiarchis; Milward, David; Winter, Andrew; Lu, Susan; Ball, Robert

2018-05-31

The FDA Adverse Event Reporting System (FAERS) is a primary data source for identifying unlabeled adverse events (AEs) in a drug or biologic drug product's postmarketing phase. Many AE reports must be reviewed by drug safety experts to identify unlabeled AEs, even if the reported AEs are previously identified, labeled AEs. Integrating the labeling status of drug product AEs into FAERS could increase report triage and review efficiency. Medical Dictionary for Regulatory Activities (MedDRA) is the standard for coding AE terms in FAERS cases. However, drug manufacturers are not required to use MedDRA to describe AEs in product labels. We hypothesized that natural language processing (NLP) tools could assist in automating the extraction and MedDRA mapping of AE terms in drug product labels. We evaluated the performance of three NLP systems, (ETHER, I2E, MetaMap) for their ability to extract AE terms from drug labels and translate the terms to MedDRA Preferred Terms (PTs). Pharmacovigilance-based annotation guidelines for extracting AE terms from drug labels were developed for this study. We compared each system's output to MedDRA PT AE lists, manually mapped by FDA pharmacovigilance experts using the guidelines, for ten drug product labels known as the "gold standard AE list" (GSL) dataset. Strict time and configuration conditions were imposed in order to test each system's capabilities under conditions of no human intervention and minimal system configuration. Each NLP system's output was evaluated for precision, recall and F measure in comparison to the GSL. A qualitative error analysis (QEA) was conducted to categorize a random sample of each NLP system's false positive and false negative errors. A total of 417, 278, and 250 false positive errors occurred in the ETHER, I2E, and MetaMap outputs, respectively. A total of 100, 80, and 187 false negative errors occurred in ETHER, I2E, and MetaMap outputs, respectively. Precision ranged from 64% to 77%, recall from 64% to 83% and F measure from 67% to 79%. I2E had the highest precision (77%), recall (83%) and F measure (79%). ETHER had the lowest precision (64%). MetaMap had the lowest recall (64%). The QEA found that the most prevalent false positive errors were context errors such as "Context error/General term", "Context error/Instructions or monitoring parameters", "Context error/Medical history preexisting condition underlying condition risk factor or contraindication", and "Context error/AE manifestations or secondary complication". The most prevalent false negative errors were in the "Incomplete or missed extraction" error category. Missing AE terms were typically due to long terms, or terms containing non-contiguous words which do not correspond exactly to MedDRA synonyms. MedDRA mapping errors were a minority of errors for ETHER and I2E but were the most prevalent false positive errors for MetaMap. The results demonstrate that it may be feasible to use NLP tools to extract and map AE terms to MedDRA PTs. However, the NLP tools we tested would need to be modified or reconfigured to lower the error rates to support their use in a regulatory setting. Tools specific for extracting AE terms from drug labels and mapping the terms to MedDRA PTs may need to be developed to support pharmacovigilance. Conducting research using additional NLP systems on a larger, diverse GSL would also be informative. Copyright © 2018. Published by Elsevier Inc.

Correlation Between Analog Noise Measurements and the Expected Bit Error Rate of a Digital Signal Propagating Through Passive Components

NASA Technical Reports Server (NTRS)

Warner, Joseph D.; Theofylaktos, Onoufrios

2012-01-01

A method of determining the bit error rate (BER) of a digital circuit from the measurement of the analog S-parameters of the circuit has been developed. The method is based on the measurement of the noise and the standard deviation of the noise in the S-parameters. Once the standard deviation and the mean of the S-parameters are known, the BER of the circuit can be calculated using the normal Gaussian function.

Determining the Magnetic Properties of 1 kg Mass Standards

PubMed Central

Davis, Richard S.

1995-01-01

Magnetic interactions may lead to errors in precision mass metrology. An analytical description of such magnetic errors is presented in which the roles of both the volume magnetic susceptibility and permanent magnetization are discussed. The same formalism is then used to describe in detail the calibration and operation of a susceptometer developed at the Bureau International des Poids et Mesures (BIPM). The device has been optimized for the determination of the magnetic properties of 1 kg mass standards. PMID:29151735

Galilean-invariant preconditioned central-moment lattice Boltzmann method without cubic velocity errors for efficient steady flow simulations

NASA Astrophysics Data System (ADS)

Hajabdollahi, Farzaneh; Premnath, Kannan N.

2018-05-01

Lattice Boltzmann (LB) models used for the computation of fluid flows represented by the Navier-Stokes (NS) equations on standard lattices can lead to non-Galilean-invariant (GI) viscous stress involving cubic velocity errors. This arises from the dependence of their third-order diagonal moments on the first-order moments for standard lattices, and strategies have recently been introduced to restore Galilean invariance without such errors using a modified collision operator involving corrections to either the relaxation times or the moment equilibria. Convergence acceleration in the simulation of steady flows can be achieved by solving the preconditioned NS equations, which contain a preconditioning parameter that can be used to tune the effective sound speed, and thereby alleviating the numerical stiffness. In the present paper, we present a GI formulation of the preconditioned cascaded central-moment LB method used to solve the preconditioned NS equations, which is free of cubic velocity errors on a standard lattice, for steady flows. A Chapman-Enskog analysis reveals the structure of the spurious non-GI defect terms and it is demonstrated that the anisotropy of the resulting viscous stress is dependent on the preconditioning parameter, in addition to the fluid velocity. It is shown that partial correction to eliminate the cubic velocity defects is achieved by scaling the cubic velocity terms in the off-diagonal third-order moment equilibria with the square of the preconditioning parameter. Furthermore, we develop additional corrections based on the extended moment equilibria involving gradient terms with coefficients dependent locally on the fluid velocity and the preconditioning parameter. Such parameter dependent corrections eliminate the remaining truncation errors arising from the degeneracy of the diagonal third-order moments and fully restore Galilean invariance without cubic defects for the preconditioned LB scheme on a standard lattice. Several conclusions are drawn from the analysis of the structure of the non-GI errors and the associated corrections, with particular emphasis on their dependence on the preconditioning parameter. The GI preconditioned central-moment LB method is validated for a number of complex flow benchmark problems and its effectiveness to achieve convergence acceleration and improvement in accuracy is demonstrated.

Comparison of Meropenem MICs and Susceptibilities for Carbapenemase-Producing Klebsiella pneumoniae Isolates by Various Testing Methods▿

PubMed Central

Bulik, Catharine C.; Fauntleroy, Kathy A.; Jenkins, Stephen G.; Abuali, Mayssa; LaBombardi, Vincent J.; Nicolau, David P.; Kuti, Joseph L.

2010-01-01

We describe the levels of agreement between broth microdilution, Etest, Vitek 2, Sensititre, and MicroScan methods to accurately define the meropenem MIC and categorical interpretation of susceptibility against carbapenemase-producing Klebsiella pneumoniae (KPC). A total of 46 clinical K. pneumoniae isolates with KPC genotypes, all modified Hodge test and blaKPC positive, collected from two hospitals in NY were included. Results obtained by each method were compared with those from broth microdilution (the reference method), and agreement was assessed based on MICs and Clinical Laboratory Standards Institute (CLSI) interpretative criteria using 2010 susceptibility breakpoints. Based on broth microdilution, 0%, 2.2%, and 97.8% of the KPC isolates were classified as susceptible, intermediate, and resistant to meropenem, respectively. Results from MicroScan demonstrated the most agreement with those from broth microdilution, with 95.6% agreement based on the MIC and 2.2% classified as minor errors, and no major or very major errors. Etest demonstrated 82.6% agreement with broth microdilution MICs, a very major error rate of 2.2%, and a minor error rate of 2.2%. Vitek 2 MIC agreement was 30.4%, with a 23.9% very major error rate and a 39.1% minor error rate. Sensititre demonstrated MIC agreement for 26.1% of isolates, with a 3% very major error rate and a 26.1% minor error rate. Application of FDA breakpoints had little effect on minor error rates but increased very major error rates to 58.7% for Vitek 2 and Sensititre. Meropenem MIC results and categorical interpretations for carbapenemase-producing K. pneumoniae differ by methodology. Confirmation of testing results is encouraged when an accurate MIC is required for antibiotic dosing optimization. PMID:20484603

Geolocation error tracking of ZY-3 three line cameras

NASA Astrophysics Data System (ADS)

Pan, Hongbo

2017-01-01

The high-accuracy geolocation of high-resolution satellite images (HRSIs) is a key issue for mapping and integrating multi-temporal, multi-sensor images. In this manuscript, we propose a new geometric frame for analysing the geometric error of a stereo HRSI, in which the geolocation error can be divided into three parts: the epipolar direction, cross base direction, and height direction. With this frame, we proved that the height error of three line cameras (TLCs) is independent of nadir images, and that the terrain effect has a limited impact on the geolocation errors. For ZY-3 error sources, the drift error in both the pitch and roll angle and its influence on the geolocation accuracy are analysed. Epipolar and common tie-point constraints are proposed to study the bundle adjustment of HRSIs. Epipolar constraints explain that the relative orientation can reduce the number of compensation parameters in the cross base direction and have a limited impact on the height accuracy. The common tie points adjust the pitch-angle errors to be consistent with each other for TLCs. Therefore, free-net bundle adjustment of a single strip cannot significantly improve the geolocation accuracy. Furthermore, the epipolar and common tie-point constraints cause the error to propagate into the adjacent strip when multiple strips are involved in the bundle adjustment, which results in the same attitude uncertainty throughout the whole block. Two adjacent strips-Orbit 305 and Orbit 381, covering 7 and 12 standard scenes separately-and 308 ground control points (GCPs) were used for the experiments. The experiments validate the aforementioned theory. The planimetric and height root mean square errors were 2.09 and 1.28 m, respectively, when two GCPs were settled at the beginning and end of the block.

A modified technique to reduce tibial keel cutting errors during an Oxford unicompartmental knee arthroplasty.

PubMed

Inui, Hiroshi; Taketomi, Shuji; Tahara, Keitarou; Yamagami, Ryota; Sanada, Takaki; Tanaka, Sakae

2017-03-01

Bone cutting errors can cause malalignment of unicompartmental knee arthroplasties (UKA). Although the extent of tibial malalignment due to horizontal cutting errors has been well reported, there is a lack of studies evaluating malalignment as a consequence of keel cutting errors, particularly in the Oxford UKA. The purpose of this study was to examine keel cutting errors during Oxford UKA placement using a navigation system and to clarify whether two different tibial keel cutting techniques would have different error rates. The alignment of the tibial cut surface after a horizontal osteotomy and the surface of the tibial trial component was measured with a navigation system. Cutting error was defined as the angular difference between these measurements. The following two techniques were used: the standard "pushing" technique in 83 patients (group P) and a modified "dolphin" technique in 41 patients (group D). In all 123 patients studied, the mean absolute keel cutting error was 1.7° and 1.4° in the coronal and sagittal planes, respectively. In group P, there were 22 outlier patients (27 %) in the coronal plane and 13 (16 %) in the sagittal plane. Group D had three outlier patients (8 %) in the coronal plane and none (0 %) in the sagittal plane. Significant differences were observed in the outlier ratio of these techniques in both the sagittal (P = 0.014) and coronal (P = 0.008) planes. Our study demonstrated overall keel cutting errors of 1.7° in the coronal plane and 1.4° in the sagittal plane. The "dolphin" technique was found to significantly reduce keel cutting errors on the tibial side. This technique will be useful for accurate component positioning and therefore improve the longevity of Oxford UKAs. Retrospective comparative study, Level III.

tPA Prescription and Administration Errors within a Regional Stroke System

PubMed Central

Chung, Lee S; Tkach, Aleksander; Lingenfelter, Erin M; Dehoney, Sarah; Rollo, Jeannie; de Havenon, Adam; DeWitt, Lucy Dana; Grantz, Matthew Ryan; Wang, Haimei; Wold, Jana J; Hannon, Peter M; Weathered, Natalie R; Majersik, Jennifer J

2015-01-01

Background IV tPA utilization in acute ischemic stroke (AIS) requires weight-based dosing and a standardized infusion rate. In our regional network, we have tried to minimize tPA dosing errors. We describe the frequency and types of tPA administration errors made in our comprehensive stroke center (CSC) and at community hospitals (CHs) prior to transfer. Methods Using our stroke quality database, we extracted clinical and pharmacy information on all patients who received IV tPA from 2010–11 at the CSC or CH prior to transfer. All records were analyzed for the presence of inclusion/exclusion criteria deviations or tPA errors in prescription, reconstitution, dispensing, or administration, and analyzed for association with outcomes. Results We identified 131 AIS cases treated with IV tPA: 51% female; mean age 68; 32% treated at CSC, 68% at CH (including 26% by telestroke) from 22 CHs. tPA prescription and administration errors were present in 64% of all patients (41% CSC, 75% CH, p<0.001), the most common being incorrect dosage for body weight (19% CSC, 55% CH, p<0.001). Of the 27 overdoses, there were 3 deaths due to systemic hemorrhage or ICH. Nonetheless, outcomes (parenchymal hematoma, mortality, mRS) did not differ between CSC and CH patients nor between those with and without errors. Conclusion Despite focus on minimization of tPA administration errors in AIS patients, such errors were very common in our regional stroke system. Although an association between tPA errors and stroke outcomes was not demonstrated, quality assurance mechanisms are still necessary to reduce potentially dangerous, avoidable errors. PMID:26698642

[Error prevention through management of complications in urology: standard operating procedures from commercial aviation as a model].

PubMed

Kranz, J; Sommer, K-J; Steffens, J

2014-05-01

Patient safety and risk/complication management rank among the current megatrends in modern medicine, which has undoubtedly become more complex. In time-critical, error-prone and difficult situations, which often occur repeatedly in everyday clinical practice, guidelines are inappropriate for acting rapidly and intelligently. With the establishment and consistent use of standard operating procedures like in commercial aviation, a possible strategic approach is available. These medical aids to decision-making - quick reference cards - are short, optimized instructions that enable a standardized procedure in case of medical claims.

Formulation of the proper equations for developing standards in coherent dual polarisation SAR imaging

NASA Astrophysics Data System (ADS)

Boerner, W.-M.; Kostinski, A. B.

1988-08-01

Crucial inconsistencies in the basic equations of radar polarimetry which are common in the literature were detected. The formulations of the polarization state definitions given in the IEEE/ANSI Standards 149-1979 are in error. These and other inconsistencies and conceptual errors are discussed. The correct formulae for the proposed revision of the polarimetric standards together with a well-defined and consistent procedure for measuring target scattering matrices in monostatic and bistatic arrangements are given. The proposed procedure can be applied to an arbitrary measurement process in any general elliptical polarization basis.

Glaucoma and Driving: On-Road Driving Characteristics

PubMed Central

Wood, Joanne M.; Black, Alex A.; Mallon, Kerry; Thomas, Ravi; Owsley, Cynthia

2016-01-01

Purpose To comprehensively investigate the types of driving errors and locations that are most problematic for older drivers with glaucoma compared to those without glaucoma using a standardized on-road assessment. Methods Participants included 75 drivers with glaucoma (mean = 73.2±6.0 years) with mild to moderate field loss (better-eye MD = -1.21 dB; worse-eye MD = -7.75 dB) and 70 age-matched controls without glaucoma (mean = 72.6 ± 5.0 years). On-road driving performance was assessed in a dual-brake vehicle by an occupational therapist using a standardized scoring system which assessed the types of driving errors and the locations where they were made and the number of critical errors that required an instructor intervention. Driving safety was rated on a 10-point scale. Self-reported driving ability and difficulties were recorded using the Driving Habits Questionnaire. Results Drivers with glaucoma were rated as significantly less safe, made more driving errors, and had almost double the rate of critical errors than those without glaucoma. Driving errors involved lane positioning and planning/approach, and were significantly more likely to occur at traffic lights and yield/give-way intersections. There were few between group differences in self-reported driving ability. Conclusions Older drivers with glaucoma with even mild to moderate field loss exhibit impairments in driving ability, particularly during complex driving situations that involve tactical problems with lane-position, planning ahead and observation. These results, together with the fact that these drivers self-report their driving to be relatively good, reinforce the need for evidence-based on-road assessments for evaluating driving fitness. PMID:27472221

Glaucoma and Driving: On-Road Driving Characteristics.

PubMed

Wood, Joanne M; Black, Alex A; Mallon, Kerry; Thomas, Ravi; Owsley, Cynthia

2016-01-01

To comprehensively investigate the types of driving errors and locations that are most problematic for older drivers with glaucoma compared to those without glaucoma using a standardized on-road assessment. Participants included 75 drivers with glaucoma (mean = 73.2±6.0 years) with mild to moderate field loss (better-eye MD = -1.21 dB; worse-eye MD = -7.75 dB) and 70 age-matched controls without glaucoma (mean = 72.6 ± 5.0 years). On-road driving performance was assessed in a dual-brake vehicle by an occupational therapist using a standardized scoring system which assessed the types of driving errors and the locations where they were made and the number of critical errors that required an instructor intervention. Driving safety was rated on a 10-point scale. Self-reported driving ability and difficulties were recorded using the Driving Habits Questionnaire. Drivers with glaucoma were rated as significantly less safe, made more driving errors, and had almost double the rate of critical errors than those without glaucoma. Driving errors involved lane positioning and planning/approach, and were significantly more likely to occur at traffic lights and yield/give-way intersections. There were few between group differences in self-reported driving ability. Older drivers with glaucoma with even mild to moderate field loss exhibit impairments in driving ability, particularly during complex driving situations that involve tactical problems with lane-position, planning ahead and observation. These results, together with the fact that these drivers self-report their driving to be relatively good, reinforce the need for evidence-based on-road assessments for evaluating driving fitness.

Counting-backward test for executive function in idiopathic normal pressure hydrocephalus.

PubMed

Kanno, S; Saito, M; Hayashi, A; Uchiyama, M; Hiraoka, K; Nishio, Y; Hisanaga, K; Mori, E

2012-10-01

The aim of this study was to develop and validate a bedside test for executive function in patients with idiopathic normal pressure hydrocephalus (INPH). Twenty consecutive patients with INPH and 20 patients with Alzheimer's disease (AD) were enrolled in this study. We developed the counting-backward test for evaluating executive function in patients with INPH. Two indices that are considered to be reflective of the attention deficits and response suppression underlying executive dysfunction in INPH were calculated: the first-error score and the reverse-effect index. Performance on both the counting-backward test and standard neuropsychological tests for executive function was assessed in INPH and AD patients. The first-error score, reverse-effect index and the scores from the standard neuropsychological tests for executive function were significantly lower for individuals in the INPH group than in the AD group. The two indices for the counting-backward test in the INPH group were strongly correlated with the total scores for Frontal Assessment Battery and Phonemic Verbal Fluency. The first-error score was also significantly correlated with the error rate of the Stroop colour-word test and the score of the go/no-go test. In addition, we found that the first-error score highly distinguished patients with INPH from those with AD using these tests. The counting-backward test is useful for evaluating executive dysfunction in INPH and for differentiating between INPH and AD patients. In particular, the first-error score may reflect deficits in the response suppression related to executive dysfunction in INPH. © 2012 John Wiley & Sons A/S.

Cortical regions involved in semantic processing investigated by repetitive navigated transcranial magnetic stimulation and object naming.

PubMed

Sollmann, Nico; Tanigawa, Noriko; Tussis, Lorena; Hauck, Theresa; Ille, Sebastian; Maurer, Stefanie; Negwer, Chiara; Zimmer, Claus; Ringel, Florian; Meyer, Bernhard; Krieg, Sandro M

2015-04-01

Knowledge about the cortical representation of semantic processing is mainly derived from functional magnetic resonance imaging (fMRI) or direct cortical stimulation (DCS) studies. Because DCS is regarded as the gold standard in terms of language mapping but can only be used during awake surgery due to its invasive character, repetitive navigated transcranial magnetic stimulation (rTMS)—a non-invasive modality that uses a similar technique as DCS—seems highly feasible for use in the investigation of semantic processing in the healthy human brain. A total number of 100 (50 left-hemispheric and 50 right-hemispheric) rTMS-based language mappings were performed in 50 purely right-handed, healthy volunteers during an object-naming task. All rTMS-induced semantic naming errors were then counted and evaluated systematically. Furthermore, since the distribution of stimulations within both hemispheres varied between individuals and cortical regions stimulated, all elicited errors were standardized and subsequently related to their cortical sites by projecting the mapping results into the cortical parcellation system (CPS). Overall, the most left-hemispheric semantic errors were observed after targeting the rTMS to the posterior middle frontal gyrus (pMFG; standardized error rate: 7.3‰), anterior supramarginal gyrus (aSMG; 5.6‰), and ventral postcentral gyrus (vPoG; 5.0‰). In contrast to that, the highest right-hemispheric error rates occurred after stimulation of the posterior superior temporal gyrus (pSTG; 12.4‰), middle superior temporal gyrus (mSTG; 6.2‰), and anterior supramarginal gyrus (aSMG; 6.2‰). Although error rates were low, the rTMS-based approach of investigating semantic processing during object naming shows convincing results compared to the current literature. Therefore, rTMS seems a valuable, safe, and reliable tool for the investigation of semantic processing within the healthy human brain. Copyright © 2015 Elsevier Ltd. All rights reserved.

Error behaviors associated with loss of competency in Alzheimer's disease.

PubMed

Marson, D C; Annis, S M; McInturff, B; Bartolucci, A; Harrell, L E

1999-12-10

To investigate qualitative behavioral changes associated with declining medical decision-making capacity (competency) in patients with AD. Qualitative measures can yield clinical information about functional changes in neurologic disease not available through quantitative measures. Normal older controls (n = 21) and patients with mild and moderate probable AD (n = 72) were compared using a standardized competency measure and neuropsychological measures. A system of 16 qualitative error scores representing conceptual domains of language, executive dysfunction, affective dysfunction, and compensatory responses was used to analyze errors produced on the competency measure. Patterns of errors were examined across groups. Relationships between error behaviors and competency performance were determined, and neurocognitive correlates of specific error behaviors were identified. AD patients demonstrated more miscomprehension, factual confusion, intrusions, incoherent responses, nonresponsive answers, loss of task, and delegation than controls. Errors in the executive domain (loss of task, nonresponsive answer, and loss of detachment) were key predictors of declining competency performance by AD patients. Neuropsychological analyses in the AD group generally confirmed the conceptual domain assignments of the qualitative scores. Loss of task, nonresponsive answers, and loss of detachment were key behavioral changes associated with declining competency of AD patients and with neurocognitive measures of executive dysfunction. These findings support the growing linkage between executive dysfunction and competency loss.

Combined proportional and additive residual error models in population pharmacokinetic modelling.

PubMed

Proost, Johannes H

2017-11-15

In pharmacokinetic modelling, a combined proportional and additive residual error model is often preferred over a proportional or additive residual error model. Different approaches have been proposed, but a comparison between approaches is still lacking. The theoretical background of the methods is described. Method VAR assumes that the variance of the residual error is the sum of the statistically independent proportional and additive components; this method can be coded in three ways. Method SD assumes that the standard deviation of the residual error is the sum of the proportional and additive components. Using datasets from literature and simulations based on these datasets, the methods are compared using NONMEM. The different coding of methods VAR yield identical results. Using method SD, the values of the parameters describing residual error are lower than for method VAR, but the values of the structural parameters and their inter-individual variability are hardly affected by the choice of the method. Both methods are valid approaches in combined proportional and additive residual error modelling, and selection may be based on OFV. When the result of an analysis is used for simulation purposes, it is essential that the simulation tool uses the same method as used during analysis. Copyright © 2017 Elsevier B.V. All rights reserved.

An Enhanced MEMS Error Modeling Approach Based on Nu-Support Vector Regression

PubMed Central

Bhatt, Deepak; Aggarwal, Priyanka; Bhattacharya, Prabir; Devabhaktuni, Vijay

2012-01-01

Micro Electro Mechanical System (MEMS)-based inertial sensors have made possible the development of a civilian land vehicle navigation system by offering a low-cost solution. However, the accurate modeling of the MEMS sensor errors is one of the most challenging tasks in the design of low-cost navigation systems. These sensors exhibit significant errors like biases, drift, noises; which are negligible for higher grade units. Different conventional techniques utilizing the Gauss Markov model and neural network method have been previously utilized to model the errors. However, Gauss Markov model works unsatisfactorily in the case of MEMS units due to the presence of high inherent sensor errors. On the other hand, modeling the random drift utilizing Neural Network (NN) is time consuming, thereby affecting its real-time implementation. We overcome these existing drawbacks by developing an enhanced Support Vector Machine (SVM) based error model. Unlike NN, SVMs do not suffer from local minimisation or over-fitting problems and delivers a reliable global solution. Experimental results proved that the proposed SVM approach reduced the noise standard deviation by 10–35% for gyroscopes and 61–76% for accelerometers. Further, positional error drifts under static conditions improved by 41% and 80% in comparison to NN and GM approaches. PMID:23012552

DOE Office of Scientific and Technical Information (OSTI.GOV)

Morley, Steven

The PyForecastTools package provides Python routines for calculating metrics for model validation, forecast verification and model comparison. For continuous predictands the package provides functions for calculating bias (mean error, mean percentage error, median log accuracy, symmetric signed bias), and for calculating accuracy (mean squared error, mean absolute error, mean absolute scaled error, normalized RMSE, median symmetric accuracy). Convenience routines to calculate the component parts (e.g. forecast error, scaled error) of each metric are also provided. To compare models the package provides: generic skill score; percent better. Robust measures of scale including median absolute deviation, robust standard deviation, robust coefficient ofmore » variation and the Sn estimator are all provided by the package. Finally, the package implements Python classes for NxN contingency tables. In the case of a multi-class prediction, accuracy and skill metrics such as proportion correct and the Heidke and Peirce skill scores are provided as object methods. The special case of a 2x2 contingency table inherits from the NxN class and provides many additional metrics for binary classification: probability of detection, probability of false detection, false alarm ration, threat score, equitable threat score, bias. Confidence intervals for many of these quantities can be calculated using either the Wald method or Agresti-Coull intervals.« less

Errors in laboratory medicine: practical lessons to improve patient safety.

PubMed

Howanitz, Peter J

2005-10-01

Patient safety is influenced by the frequency and seriousness of errors that occur in the health care system. Error rates in laboratory practices are collected routinely for a variety of performance measures in all clinical pathology laboratories in the United States, but a list of critical performance measures has not yet been recommended. The most extensive databases describing error rates in pathology were developed and are maintained by the College of American Pathologists (CAP). These databases include the CAP's Q-Probes and Q-Tracks programs, which provide information on error rates from more than 130 interlaboratory studies. To define critical performance measures in laboratory medicine, describe error rates of these measures, and provide suggestions to decrease these errors, thereby ultimately improving patient safety. A review of experiences from Q-Probes and Q-Tracks studies supplemented with other studies cited in the literature. Q-Probes studies are carried out as time-limited studies lasting 1 to 4 months and have been conducted since 1989. In contrast, Q-Tracks investigations are ongoing studies performed on a yearly basis and have been conducted only since 1998. Participants from institutions throughout the world simultaneously conducted these studies according to specified scientific designs. The CAP has collected and summarized data for participants about these performance measures, including the significance of errors, the magnitude of error rates, tactics for error reduction, and willingness to implement each of these performance measures. A list of recommended performance measures, the frequency of errors when these performance measures were studied, and suggestions to improve patient safety by reducing these errors. Error rates for preanalytic and postanalytic performance measures were higher than for analytic measures. Eight performance measures were identified, including customer satisfaction, test turnaround times, patient identification, specimen acceptability, proficiency testing, critical value reporting, blood product wastage, and blood culture contamination. Error rate benchmarks for these performance measures were cited and recommendations for improving patient safety presented. Not only has each of the 8 performance measures proven practical, useful, and important for patient care, taken together, they also fulfill regulatory requirements. All laboratories should consider implementing these performance measures and standardizing their own scientific designs, data analysis, and error reduction strategies according to findings from these published studies.

Special electronic distance meter calibration for precise engineering surveying industrial applications

NASA Astrophysics Data System (ADS)

Braun, Jaroslav; Štroner, Martin; Urban, Rudolf

2015-05-01

All surveying instruments and their measurements suffer from some errors. To refine the measurement results, it is necessary to use procedures restricting influence of the instrument errors on the measured values or to implement numerical corrections. In precise engineering surveying industrial applications the accuracy of the distances usually realized on relatively short distance is a key parameter limiting the resulting accuracy of the determined values (coordinates, etc.). To determine the size of systematic and random errors of the measured distances were made test with the idea of the suppression of the random error by the averaging of the repeating measurement, and reducing systematic errors influence of by identifying their absolute size on the absolute baseline realized in geodetic laboratory at the Faculty of Civil Engineering CTU in Prague. The 16 concrete pillars with forced centerings were set up and the absolute distances between the points were determined with a standard deviation of 0.02 millimetre using a Leica Absolute Tracker AT401. For any distance measured by the calibrated instruments (up to the length of the testing baseline, i.e. 38.6 m) can now be determined the size of error correction of the distance meter in two ways: Firstly by the interpolation on the raw data, or secondly using correction function derived by previous FFT transformation usage. The quality of this calibration and correction procedure was tested on three instruments (Trimble S6 HP, Topcon GPT-7501, Trimble M3) experimentally using Leica Absolute Tracker AT401. By the correction procedure was the standard deviation of the measured distances reduced significantly to less than 0.6 mm. In case of Topcon GPT-7501 is the nominal standard deviation 2 mm, achieved (without corrections) 2.8 mm and after corrections 0.55 mm; in case of Trimble M3 is nominal standard deviation 3 mm, achieved (without corrections) 1.1 mm and after corrections 0.58 mm; and finally in case of Trimble S6 is nominal standard deviation 1 mm, achieved (without corrections) 1.2 mm and after corrections 0.51 mm. Proposed procedure of the calibration and correction is in our opinion very suitable for increasing of the accuracy of the electronic distance measurement and allows the use of the common surveying instrument to achieve uncommonly high precision.

First-principles energetics of water clusters and ice: A many-body analysis

NASA Astrophysics Data System (ADS)

Gillan, M. J.; Alfè, D.; Bartók, A. P.; Csányi, G.

2013-12-01

Standard forms of density-functional theory (DFT) have good predictive power for many materials, but are not yet fully satisfactory for cluster, solid, and liquid forms of water. Recent work has stressed the importance of DFT errors in describing dispersion, but we note that errors in other parts of the energy may also contribute. We obtain information about the nature of DFT errors by using a many-body separation of the total energy into its 1-body, 2-body, and beyond-2-body components to analyze the deficiencies of the popular PBE and BLYP approximations for the energetics of water clusters and ice structures. The errors of these approximations are computed by using accurate benchmark energies from the coupled-cluster technique of molecular quantum chemistry and from quantum Monte Carlo calculations. The systems studied are isomers of the water hexamer cluster, the crystal structures Ih, II, XV, and VIII of ice, and two clusters extracted from ice VIII. For the binding energies of these systems, we use the machine-learning technique of Gaussian Approximation Potentials to correct successively for 1-body and 2-body errors of the DFT approximations. We find that even after correction for these errors, substantial beyond-2-body errors remain. The characteristics of the 2-body and beyond-2-body errors of PBE are completely different from those of BLYP, but the errors of both approximations disfavor the close approach of non-hydrogen-bonded monomers. We note the possible relevance of our findings to the understanding of liquid water.

A Model of Self-Monitoring Blood Glucose Measurement Error.

PubMed

Vettoretti, Martina; Facchinetti, Andrea; Sparacino, Giovanni; Cobelli, Claudio

2017-07-01

A reliable model of the probability density function (PDF) of self-monitoring of blood glucose (SMBG) measurement error would be important for several applications in diabetes, like testing in silico insulin therapies. In the literature, the PDF of SMBG error is usually described by a Gaussian function, whose symmetry and simplicity are unable to properly describe the variability of experimental data. Here, we propose a new methodology to derive more realistic models of SMBG error PDF. The blood glucose range is divided into zones where error (absolute or relative) presents a constant standard deviation (SD). In each zone, a suitable PDF model is fitted by maximum-likelihood to experimental data. Model validation is performed by goodness-of-fit tests. The method is tested on two databases collected by the One Touch Ultra 2 (OTU2; Lifescan Inc, Milpitas, CA) and the Bayer Contour Next USB (BCN; Bayer HealthCare LLC, Diabetes Care, Whippany, NJ). In both cases, skew-normal and exponential models are used to describe the distribution of errors and outliers, respectively. Two zones were identified: zone 1 with constant SD absolute error; zone 2 with constant SD relative error. Goodness-of-fit tests confirmed that identified PDF models are valid and superior to Gaussian models used so far in the literature. The proposed methodology allows to derive realistic models of SMBG error PDF. These models can be used in several investigations of present interest in the scientific community, for example, to perform in silico clinical trials to compare SMBG-based with nonadjunctive CGM-based insulin treatments.

Pilot error in air carrier accidents: does age matter?

PubMed

Li, Guohua; Grabowski, Jurek G; Baker, Susan P; Rebok, George W

2006-07-01

The relationship between pilot age and safety performance has been the subject of research and controversy since the "Age 60 Rule" became effective in 1960. This study aimed to examine age-related differences in the prevalence and patterns of pilot error in air carrier accidents. Investigation reports from the National Transportation Safety Board for accidents involving Part 121 operations in the United States between 1983 and 2002 were reviewed to identify pilot error and other contributing factors. Accident circumstances and the presence and type of pilot error were analyzed in relation to pilot age using Chi-square tests. Of the 558 air carrier accidents studied, 25% resulted from turbulence, 21% from mechanical failure, 16% from taxiing events, 13% from loss of control at landing or takeoff, and 25% from other causes. Accidents involving older pilots were more likely to be caused by turbulence, whereas accidents involving younger pilots were more likely to be taxiing events. Pilot error was a contributing factor in 34%, 38%, 35%, and 34% of the accidents involving pilots ages 25-34 yr, 35-44 yr, 45-54 yr, and 55-59 yr, respectively (p = 0.87). The patterns of pilot error were similar across age groups. Overall, 26% of the pilot errors identified were inattentiveness, 22% flawed decisions, 22% mishandled aircraft kinetics, and 11% poor crew interactions. The prevalence and patterns of pilot error in air carrier accidents do not seem to change with pilot age. The lack of association between pilot age and error may be due to the "safe worker effect" resulting from the rigorous selection processes and certification standards for professional pilots.

Failure mode and effective analysis ameliorate awareness of medical errors: a 4-year prospective observational study in critically ill children.

PubMed

Daverio, Marco; Fino, Giuliana; Luca, Brugnaro; Zaggia, Cristina; Pettenazzo, Andrea; Parpaiola, Antonella; Lago, Paola; Amigoni, Angela

2015-12-01

Errors in are estimated to occur with an incidence of 3.7-16.6% in hospitalized patients. The application of systems for detection of adverse events is becoming a widespread reality in healthcare. Incident reporting (IR) and failure mode and effective analysis (FMEA) are strategies widely used to detect errors, but no studies have combined them in the setting of a pediatric intensive care unit (PICU). The aim of our study was to describe the trend of IR in a PICU and evaluate the effect of FMEA application on the number and severity of the errors detected. With this prospective observational study, we evaluated the frequency IR documented in standard IR forms completed from January 2009 to December 2012 in the PICU of Woman's and Child's Health Department of Padova. On the basis of their severity, errors were classified as: without outcome (55%), with minor outcome (16%), with moderate outcome (10%), and with major outcome (3%); 16% of reported incidents were 'near misses'. We compared the data before and after the introduction of FMEA. Sixty-nine errors were registered, 59 (86%) concerning drug therapy (83% during prescription). Compared to 2009-2010, in 2011-2012, we noted an increase of reported errors (43 vs 26) with a reduction of their severity (21% vs 8% 'near misses' and 65% vs 38% errors with no outcome). With the introduction of FMEA, we obtained an increased awareness in error reporting. Application of these systems will improve the quality of healthcare services. © 2015 John Wiley & Sons Ltd.

Cognitive tests predict real-world errors: the relationship between drug name confusion rates in laboratory-based memory and perception tests and corresponding error rates in large pharmacy chains.

PubMed

Schroeder, Scott R; Salomon, Meghan M; Galanter, William L; Schiff, Gordon D; Vaida, Allen J; Gaunt, Michael J; Bryson, Michelle L; Rash, Christine; Falck, Suzanne; Lambert, Bruce L

2017-05-01

Drug name confusion is a common type of medication error and a persistent threat to patient safety. In the USA, roughly one per thousand prescriptions results in the wrong drug being filled, and most of these errors involve drug names that look or sound alike. Prior to approval, drug names undergo a variety of tests to assess their potential for confusability, but none of these preapproval tests has been shown to predict real-world error rates. We conducted a study to assess the association between error rates in laboratory-based tests of drug name memory and perception and real-world drug name confusion error rates. Eighty participants, comprising doctors, nurses, pharmacists, technicians and lay people, completed a battery of laboratory tests assessing visual perception, auditory perception and short-term memory of look-alike and sound-alike drug name pairs (eg, hydroxyzine/hydralazine). Laboratory test error rates (and other metrics) significantly predicted real-world error rates obtained from a large, outpatient pharmacy chain, with the best-fitting model accounting for 37% of the variance in real-world error rates. Cross-validation analyses confirmed these results, showing that the laboratory tests also predicted errors from a second pharmacy chain, with 45% of the variance being explained by the laboratory test data. Across two distinct pharmacy chains, there is a strong and significant association between drug name confusion error rates observed in the real world and those observed in laboratory-based tests of memory and perception. Regulators and drug companies seeking a validated preapproval method for identifying confusing drug names ought to consider using these simple tests. By using a standard battery of memory and perception tests, it should be possible to reduce the number of confusing look-alike and sound-alike drug name pairs that reach the market, which will help protect patients from potentially harmful medication errors. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.

Prescribing errors in adult congenital heart disease patients admitted to a pediatric cardiovascular intensive care unit.

PubMed

Echeta, Genevieve; Moffett, Brady S; Checchia, Paul; Benton, Mary Kay; Klouda, Leda; Rodriguez, Fred H; Franklin, Wayne

2014-01-01

Adults with congenital heart disease (CHD) are often cared for at pediatric hospitals. There are no data describing the incidence or type of medication prescribing errors in adult patients admitted to a pediatric cardiovascular intensive care unit (CVICU). A review of patients >18 years of age admitted to the pediatric CVICU at our institution from 2009 to 2011 occurred. A comparator group <18 years of age but >70 kg (a typical adult weight) was identified. Medication prescribing errors were determined according to a commonly used adult drug reference. An independent panel consisting of a physician specializing in the care of adult CHD patients, a nurse, and a pharmacist evaluated all errors. Medication prescribing orders were classified as appropriate, underdose, overdose, or nonstandard (dosing per weight instead of standard adult dosing), and severity of error was classified. Eighty-five adult (74 patients) and 33 pediatric admissions (32 patients) met study criteria (mean age 27.5 ± 9.4 years, 53% male vs. 14.9 ± 1.8 years, 63% male). A cardiothoracic surgical procedure occurred in 81.4% of admissions. Adult admissions weighed less than pediatric admissions (72.8 ± 22.4 kg vs. 85.6 ± 14.9 kg, P < .01) but hospital length of stay was similar. (Adult 6 days [range 1-216 days]; pediatric 5 days [Range 2-123 days], P = .52.) A total of 112 prescribing errors were identified and they occurred less often in adults (42.4% of admissions vs. 66.7% of admissions, P = .02). Adults had a lower mean number of errors (0.7 errors per adult admission vs. 1.7 errors per pediatric admission, P < .01). Prescribing errors occurred most commonly with antimicrobials (n = 27). Underdosing was the most common category of prescribing error. Most prescribing errors were determined to have not caused harm to the patient. Prescribing errors occur frequently in adult patients admitted to a pediatric CVICU but occur more often in pediatric patients of adult weight. © 2013 Wiley Periodicals, Inc.

Distribution of the two-sample t-test statistic following blinded sample size re-estimation.

PubMed

Lu, Kaifeng

2016-05-01

We consider the blinded sample size re-estimation based on the simple one-sample variance estimator at an interim analysis. We characterize the exact distribution of the standard two-sample t-test statistic at the final analysis. We describe a simulation algorithm for the evaluation of the probability of rejecting the null hypothesis at given treatment effect. We compare the blinded sample size re-estimation method with two unblinded methods with respect to the empirical type I error, the empirical power, and the empirical distribution of the standard deviation estimator and final sample size. We characterize the type I error inflation across the range of standardized non-inferiority margin for non-inferiority trials, and derive the adjusted significance level to ensure type I error control for given sample size of the internal pilot study. We show that the adjusted significance level increases as the sample size of the internal pilot study increases. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

Corsica: A Multi-Mission Absolute Calibration Site

NASA Astrophysics Data System (ADS)

Bonnefond, P.; Exertier, P.; Laurain, O.; Guinle, T.; Femenias, P.

2013-09-01

In collaboration with the CNES and NASA oceanographic projects (TOPEX/Poseidon and Jason), the OCA (Observatoire de la Côte d'Azur) developed a verification site in Corsica since 1996, operational since 1998. CALibration/VALidation embraces a wide variety of activities, ranging from the interpretation of information from internal-calibration modes of the sensors to validation of the fully corrected estimates of the reflector heights using in situ data. Now, Corsica is, like the Harvest platform (NASA side) [14], an operating calibration site able to support a continuous monitoring with a high level of accuracy: a 'point calibration' which yields instantaneous bias estimates with a 10-day repeatability of 30 mm (standard deviation) and mean errors of 4 mm (standard error). For a 35-day repeatability (ERS, Envisat), due to a smaller time series, the standard error is about the double ( 7 mm).In this paper, we will present updated results of the absolute Sea Surface Height (SSH) biases for TOPEX/Poseidon (T/P), Jason-1, Jason-2, ERS-2 and Envisat.

Comparison of rate one-half, equivalent constraint length 24, binary convolutional codes for use with sequential decoding on the deep-space channel

NASA Technical Reports Server (NTRS)

Massey, J. L.

1976-01-01

Virtually all previously-suggested rate 1/2 binary convolutional codes with KE = 24 are compared. Their distance properties are given; and their performance, both in computation and in error probability, with sequential decoding on the deep-space channel is determined by simulation. Recommendations are made both for the choice of a specific KE = 24 code as well as for codes to be included in future coding standards for the deep-space channel. A new result given in this report is a method for determining the statistical significance of error probability data when the error probability is so small that it is not feasible to perform enough decoding simulations to obtain more than a very small number of decoding errors.

Route Learning Impairment in Temporal Lobe Epilepsy

PubMed Central

Bell, Brian D.

2012-01-01

Memory impairment on neuropsychological tests is relatively common in temporal lobe epilepsy (TLE) patients. But memory rarely has been evaluated in more naturalistic settings. This study assessed TLE (n = 19) and control (n = 32) groups on a real-world route learning (RL) test. Compared to the controls, the TLE group committed significantly more total errors across the three RL test trials. RL errors correlated significantly with standardized auditory and visual memory and visual-perceptual test scores in the TLE group. In the TLE subset for whom hippocampal data were available (n = 14), RL errors also correlated significantly with left hippocampal volume. This is one of the first studies to demonstrate real-world memory impairment in TLE patients and its association with both mesial temporal lobe integrity and standardized memory test performance. The results support the ecological validity of clinical neuropsychological assessment. PMID:23041173

Virtual occlusal definition for orthognathic surgery.

PubMed

Liu, X J; Li, Q Q; Zhang, Z; Li, T T; Xie, Z; Zhang, Y

2016-03-01

Computer-assisted surgical simulation is being used increasingly in orthognathic surgery. However, occlusal definition is still undertaken using model surgery with subsequent digitization via surface scanning or cone beam computed tomography. A software tool has been developed and a workflow set up in order to achieve a virtual occlusal definition. The results of a validation study carried out on 60 models of normal occlusion are presented. Inter- and intra-user correlation tests were used to investigate the reproducibility of the manual setting point procedure. The errors between the virtually set positions (test) and the digitized manually set positions (gold standard) were compared. The consistency in virtual set positions performed by three individual users was investigated by one way analysis of variance test. Inter- and intra-observer correlation coefficients for manual setting points were all greater than 0.95. Overall, the median error between the test and the gold standard positions was 1.06mm. Errors did not differ among teeth (F=0.371, P>0.05). The errors were not significantly different from 1mm (P>0.05). There were no significant differences in the errors made by the three independent users (P>0.05). In conclusion, this workflow for virtual occlusal definition was found to be reliable and accurate. Copyright © 2015 International Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.

Multiple imputation to account for measurement error in marginal structural models

PubMed Central

Edwards, Jessie K.; Cole, Stephen R.; Westreich, Daniel; Crane, Heidi; Eron, Joseph J.; Mathews, W. Christopher; Moore, Richard; Boswell, Stephen L.; Lesko, Catherine R.; Mugavero, Michael J.

2015-01-01

Background Marginal structural models are an important tool for observational studies. These models typically assume that variables are measured without error. We describe a method to account for differential and non-differential measurement error in a marginal structural model. Methods We illustrate the method estimating the joint effects of antiretroviral therapy initiation and current smoking on all-cause mortality in a United States cohort of 12,290 patients with HIV followed for up to 5 years between 1998 and 2011. Smoking status was likely measured with error, but a subset of 3686 patients who reported smoking status on separate questionnaires composed an internal validation subgroup. We compared a standard joint marginal structural model fit using inverse probability weights to a model that also accounted for misclassification of smoking status using multiple imputation. Results In the standard analysis, current smoking was not associated with increased risk of mortality. After accounting for misclassification, current smoking without therapy was associated with increased mortality [hazard ratio (HR): 1.2 (95% CI: 0.6, 2.3)]. The HR for current smoking and therapy (0.4 (95% CI: 0.2, 0.7)) was similar to the HR for no smoking and therapy (0.4; 95% CI: 0.2, 0.6). Conclusions Multiple imputation can be used to account for measurement error in concert with methods for causal inference to strengthen results from observational studies. PMID:26214338

Evaluation of centroiding algorithm error for Nano-JASMINE

NASA Astrophysics Data System (ADS)

Hara, Takuji; Gouda, Naoteru; Yano, Taihei; Yamada, Yoshiyuki

2014-08-01

The Nano-JASMINE mission has been designed to perform absolute astrometric measurements with unprecedented accuracy; the end-of-mission parallax standard error is required to be of the order of 3 milli arc seconds for stars brighter than 7.5 mag in the zw-band(0.6μm-1.0μm) .These requirements set a stringent constraint on the accuracy of the estimation of the location of the stellar image on the CCD for each observation. However each stellar images have individual shape depend on the spectral energy distribution of the star, the CCD properties, and the optics and its associated wave front errors. So it is necessity that the centroiding algorithm performs a high accuracy in any observables. Referring to the study of Gaia, we use LSF fitting method for centroiding algorithm, and investigate systematic error of the algorithm for Nano-JASMINE. Furthermore, we found to improve the algorithm by restricting sample LSF when we use a Principle Component Analysis. We show that centroiding algorithm error decrease after adapted the method.

Uncertainties in the cluster-cluster correlation function

NASA Astrophysics Data System (ADS)

Ling, E. N.; Frenk, C. S.; Barrow, J. D.

1986-12-01

The bootstrap resampling technique is applied to estimate sampling errors and significance levels of the two-point correlation functions determined for a subset of the CfA redshift survey of galaxies and a redshift sample of 104 Abell clusters. The angular correlation function for a sample of 1664 Abell clusters is also calculated. The standard errors in xi(r) for the Abell data are found to be considerably larger than quoted 'Poisson errors'. The best estimate for the ratio of the correlation length of Abell clusters (richness class R greater than or equal to 1, distance class D less than or equal to 4) to that of CfA galaxies is 4.2 + 1.4 or - 1.0 (68 percentile error). The enhancement of cluster clustering over galaxy clustering is statistically significant in the presence of resampling errors. The uncertainties found do not include the effects of possible systematic biases in the galaxy and cluster catalogs and could be regarded as lower bounds on the true uncertainty range.

Spectral combination of spherical gravitational curvature boundary-value problems

NASA Astrophysics Data System (ADS)

PitoÅák, Martin; Eshagh, Mehdi; Šprlák, Michal; Tenzer, Robert; Novák, Pavel

2018-04-01

Four solutions of the spherical gravitational curvature boundary-value problems can be exploited for the determination of the Earth's gravitational potential. In this article we discuss the combination of simulated satellite gravitational curvatures, i.e., components of the third-order gravitational tensor, by merging these solutions using the spectral combination method. For this purpose, integral estimators of biased- and unbiased-types are derived. In numerical studies, we investigate the performance of the developed mathematical models for the gravitational field modelling in the area of Central Europe based on simulated satellite measurements. Firstly, we verify the correctness of the integral estimators for the spectral downward continuation by a closed-loop test. Estimated errors of the combined solution are about eight orders smaller than those from the individual solutions. Secondly, we perform a numerical experiment by considering the Gaussian noise with the standard deviation of 6.5× 10-17 m-1s-2 in the input data at the satellite altitude of 250 km above the mean Earth sphere. This value of standard deviation is equivalent to a signal-to-noise ratio of 10. Superior results with respect to the global geopotential model TIM-r5 are obtained by the spectral downward continuation of the vertical-vertical-vertical component with the standard deviation of 2.104 m2s-2, but the root mean square error is the largest and reaches 9.734 m2s-2. Using the spectral combination of all gravitational curvatures the root mean square error is more than 400 times smaller but the standard deviation reaches 17.234 m2s-2. The combination of more components decreases the root mean square error of the corresponding solutions while the standard deviations of the combined solutions do not improve as compared to the solution from the vertical-vertical-vertical component. The presented method represents a weight mean in the spectral domain that minimizes the root mean square error of the combined solutions and improves standard deviation of the solution based only on the least accurate components.

Intraobserver reliability of contact pachymetry in children.

PubMed

Weise, Katherine K; Kaminski, Brett; Melia, Michele; Repka, Michael X; Bradfield, Yasmin S; Davitt, Bradley V; Johnson, David A; Kraker, Raymond T; Manny, Ruth E; Matta, Noelle S; Schloff, Susan

2013-04-01

Central corneal thickness (CCT) is an important measurement in the treatment and management of pediatric glaucoma and potentially of refractive error, but data regarding reliability of CCT measurement in children are limited. The purpose of this study was to evaluate the reliability of CCT measurement with the use of handheld contact pachymetry in children. We conducted a multicenter intraobserver test-retest reliability study of more than 3,400 healthy eyes in children aged from newborn to 17 years by using a handheld contact pachymeter (Pachmate DGH55; DGH Technology Inc, Exton, PA) in 2 clinical settings--with the use of topical anesthesia in the office and with the patient under general anesthesia in a surgical facility. The overall standard error of measurement, including only measurements with standard deviation ≤5 μm, was 8 μm; the corresponding coefficient of repeatability, or limits within which 95% of test-retest differences fell, was ±22.3 μm. However, standard error of measurement increased as CCT increased, from 6.8 μm for CCT less than 525 μm, to 12.9 μm for CCT 625 μm and greater. The standard error of measurement including measurements with standard deviation >5 μm was 10.5 μm. Age, sex, race/ethnicity group, and examination setting did not influence the magnitude of test-retest differences. CCT measurement reliability in children via the Pachmate DGH55 handheld contact pachymeter is similar to that reported for adults. Because thicker CCT measurements are less reliable than thinner measurements, a second measure may be helpful when the first exceeds 575 μm. Reliability is also improved by disregarding measurements with instrument-reported standard deviations >5 μm. Copyright © 2013 American Association for Pediatric Ophthalmology and Strabismus. Published by Mosby, Inc. All rights reserved.

Effect of anatomical fractionation on the enzymatic hydrolysis of acid and alkaline pretreated corn stover.

PubMed

Duguid, K B; Montross, M D; Radtke, C W; Crofcheck, C L; Wendt, L M; Shearer, S A

2009-11-01

Due to concerns with biomass collection systems and soil sustainability there are opportunities to investigate the optimal plant fractions to collect for conversion. An ideal feedstock would require a low severity pretreatment to release a maximum amount of sugar during enzymatic hydrolysis. Corn stover fractions were separated manually and analyzed for glucan, xylan, acid soluble lignin, acid insoluble lignin, and ash composition. The stover fractions were also pretreated with either 0%, 0.4%, or 0.8% NaOH for 2 h at room temperature, washed, autoclaved and saccharified. In addition, dilute sulfuric acid pretreated samples underwent simultaneous saccharification and fermentation (SSF) to ethanol. In general, the two pretreatments produced similar trends with cobs, husks, and leaves responding best to the pretreatments, the tops of stalks responding slightly less, and the bottom of the stalks responding the least. For example, corn husks pretreated with 0.8% NaOH released over 90% (standard error of 3.8%) of the available glucan, while only 45% (standard error of 1.1%) of the glucan was produced from identically treated stalk bottoms. Estimates of the theoretical ethanol yield using acid pretreatment followed by SSF were 65% (standard error of 15.9%) for husks and 29% (standard error of 1.8%) for stalk bottoms. This suggests that integration of biomass collection systems to remove sustainable feedstocks could be integrated with the processes within a biorefinery to minimize overall ethanol production costs.

Cost effectiveness of the US Geological Survey's stream-gaging program in New York

USGS Publications Warehouse

Wolcott, S.W.; Gannon, W.B.; Johnston, W.H.

1986-01-01

The U.S. Geological Survey conducted a 5-year nationwide analysis to define and document the most cost effective means of obtaining streamflow data. This report describes the stream gaging network in New York and documents the cost effectiveness of its operation; it also identifies data uses and funding sources for the 174 continuous-record stream gages currently operated (1983). Those gages as well as 189 crest-stage, stage-only, and groundwater gages are operated with a budget of $1.068 million. One gaging station was identified as having insufficient reason for continuous operation and was converted to a crest-stage gage. Current operation of the 363-station program requires a budget of $1.068 million/yr. The average standard error of estimation of continuous streamflow data is 13.4%. Results indicate that this degree of accuracy could be maintained with a budget of approximately $1.006 million if the gaging resources were redistributed among the gages. The average standard error for 174 stations was calculated for five hypothetical budgets. A minimum budget of $970,000 would be needed to operated the 363-gage program; a budget less than this does not permit proper servicing and maintenance of the gages and recorders. Under the restrictions of a minimum budget, the average standard error would be 16.0%. The maximum budget analyzed was $1.2 million, which would decrease the average standard error to 9.4%. (Author 's abstract)

Effects of sharing information on drug administration errors in pediatric wards: a pre–post intervention study

PubMed Central

Chua, Siew-Siang; Choo, Sim-Mei; Sulaiman, Che Zuraini; Omar, Asma; Thong, Meow-Keong

2017-01-01

Background and purpose Drug administration errors are more likely to reach the patient than other medication errors. The main aim of this study was to determine whether the sharing of information on drug administration errors among health care providers would reduce such problems. Patients and methods This study involved direct, undisguised observations of drug administrations in two pediatric wards of a major teaching hospital in Kuala Lumpur, Malaysia. This study consisted of two phases: Phase 1 (pre-intervention) and Phase 2 (post-intervention). Data were collected by two observers over a 40-day period in both Phase 1 and Phase 2 of the study. Both observers were pharmacy graduates: Observer 1 just completed her undergraduate pharmacy degree, whereas Observer 2 was doing her one-year internship as a provisionally registered pharmacist in the hospital under study. A drug administration error was defined as a discrepancy between the drug regimen received by the patient and that intended by the prescriber and also drug administration procedures that did not follow standard hospital policies and procedures. Results from Phase 1 of the study were analyzed, presented and discussed with the ward staff before commencement of data collection in Phase 2. Results A total of 1,284 and 1,401 doses of drugs were administered in Phase 1 and Phase 2, respectively. The rate of drug administration errors reduced significantly from Phase 1 to Phase 2 (44.3% versus 28.6%, respectively; P<0.001). Logistic regression analysis showed that the adjusted odds of drug administration errors in Phase 1 of the study were almost three times that in Phase 2 (P<0.001). The most common types of errors were incorrect administration technique and incorrect drug preparation. Nasogastric and intravenous routes of drug administration contributed significantly to the rate of drug administration errors. Conclusion This study showed that sharing of the types of errors that had occurred was significantly associated with a reduction in drug administration errors. PMID:28356748

Large Sample Confidence Limits for Goodman and Kruskal's Proportional Prediction Measure TAU-b

ERIC Educational Resources Information Center

Berry, Kenneth J.; Mielke, Paul W.

1976-01-01

A Fortran Extended program which computes Goodman and Kruskal's Tau-b, its asymmetrical counterpart, Tau-a, and three sets of confidence limits for each coefficient under full multinomial and proportional stratified sampling is presented. A correction of an error in the calculation of the large sample standard error of Tau-b is discussed.…

The Influence of Item Calibration Error on Variable-Length Computerized Adaptive Testing

ERIC Educational Resources Information Center

Patton, Jeffrey M.; Cheng, Ying; Yuan, Ke-Hai; Diao, Qi

2013-01-01

Variable-length computerized adaptive testing (VL-CAT) allows both items and test length to be "tailored" to examinees, thereby achieving the measurement goal (e.g., scoring precision or classification) with as few items as possible. Several popular test termination rules depend on the standard error of the ability estimate, which in turn depends…

A Note on the Specification of Error Structures in Latent Interaction Models

ERIC Educational Resources Information Center

Mao, Xiulin; Harring, Jeffrey R.; Hancock, Gregory R.

2015-01-01

Latent interaction models have motivated a great deal of methodological research, mainly in the area of estimating such models. Product-indicator methods have been shown to be competitive with other methods of estimation in terms of parameter bias and standard error accuracy, and their continued popularity in empirical studies is due, in part, to…

An Investigation of the Standard Errors of Expected A Posteriori Ability Estimates.

ERIC Educational Resources Information Center

De Ayala, R. J.; And Others

Expected a posteriori has a number of advantages over maximum likelihood estimation or maximum a posteriori (MAP) estimation methods. These include ability estimates (thetas) for all response patterns, less regression towards the mean than MAP ability estimates, and a lower average squared error. R. D. Bock and R. J. Mislevy (1982) state that the…

Do Cognitive Patterns of Strengths and Weaknesses Differentially Predict Errors on Reading, Writing, and Spelling?

ERIC Educational Resources Information Center

Liu, Xiaochen; Marchis, Lavinia; DeBiase, Emily; Breaux, Kristina C.; Courville, Troy; Pan, Xingyu; Hatcher, Ryan C.; Koriakin, Taylor; Choi, Dowon; Kaufman, Alan S.

2017-01-01

This study investigated the relationship between specific cognitive patterns of strengths and weaknesses (PSWs) and the errors children make in reading, writing, and spelling tests from the Kaufman Test of Educational Achievement-Third Edition (KTEA-3). Participants were selected from the KTEA-3 standardization sample based on five cognitive…

Patterns of Cognitive Strengths and Weaknesses and Relationships to Math Errors

ERIC Educational Resources Information Center

Koriakin, Taylor; White, Erica; Breaux, Kristina C.; DeBiase, Emily; O'Brien, Rebecca; Howell, Meiko; Costa, Michael; Liu, Xiaochen; Pan, Xingyu; Courville, Troy

2017-01-01

This study investigated cognitive patterns of strengths and weaknesses (PSW) and their relationship to patterns of math errors on the Kaufman Test of Educational Achievement (KTEA-3). Participants, ages 5 to 18, were selected from the KTEA-3 standardization sample if they met one of two PSW profiles: high crystallized ability (Gc) paired with low…

Correcting quantum errors with entanglement.

PubMed

Brun, Todd; Devetak, Igor; Hsieh, Min-Hsiu

2006-10-20

We show how entanglement shared between encoder and decoder can simplify the theory of quantum error correction. The entanglement-assisted quantum codes we describe do not require the dual-containing constraint necessary for standard quantum error-correcting codes, thus allowing us to "quantize" all of classical linear coding theory. In particular, efficient modern classical codes that attain the Shannon capacity can be made into entanglement-assisted quantum codes attaining the hashing bound (closely related to the quantum capacity). For systems without large amounts of shared entanglement, these codes can also be used as catalytic codes, in which a small amount of initial entanglement enables quantum communication.

Bioethics for clinicians: 23. Disclosure of medical error

PubMed Central

Hébert, Philip C.; Levin, Alex V.; Robertson, Gerald

2001-01-01

ADVERSE EVENTS AND MEDICAL ERRORS ARE NOT UNCOMMON. In this article we review the literature on such events and discuss the ethical, legal and practical aspects of whether and how they should be disclosed to patients. Ethics, professional policy and the law, as well as the relevant empirical literature, suggest that timely and candid disclosure should be standard practice. Candour about error may lessen, rather than increase, the medicolegal liability of the health care professionals and may help to alleviate the patient's concerns. Guidelines for disclosure to patients, and their families if necessary, are proposed. PMID:11233873

Practical scheme for error control using feedback

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sarovar, Mohan; Milburn, Gerard J.; Ahn, Charlene

2004-05-01

We describe a scheme for quantum-error correction that employs feedback and weak measurement rather than the standard tools of projective measurement and fast controlled unitary gates. The advantage of this scheme over previous protocols [for example, Ahn et al. Phys. Rev. A 65, 042301 (2001)], is that it requires little side processing while remaining robust to measurement inefficiency, and is therefore considerably more practical. We evaluate the performance of our scheme by simulating the correction of bit flips. We also consider implementation in a solid-state quantum-computation architecture and estimate the maximal error rate that could be corrected with current technology.

''Towards a High-Performance and Robust Implementation of MPI-IO on Top of GPFS''

DOE Office of Scientific and Technical Information (OSTI.GOV)

Prost, J.P.; Tremann, R.; Blackwore, R.

2000-01-11

MPI-IO/GPFS is a prototype implementation of the I/O chapter of the Message Passing Interface (MPI) 2 standard. It uses the IBM General Parallel File System (GPFS), with prototyped extensions, as the underlying file system. this paper describes the features of this prototype which support its high performance and robustness. The use of hints at the file system level and at the MPI-IO level allows tailoring the use of the file system to the application needs. Error handling in collective operations provides robust error reporting and deadlock prevention in case of returning errors.

Validation Relaxation: A Quality Assurance Strategy for Electronic Data Collection

PubMed Central

Gordon, Nicholas; Griffiths, Thomas; Kraemer, John D; Siedner, Mark J

2017-01-01

Background The use of mobile devices for data collection in developing world settings is becoming increasingly common and may offer advantages in data collection quality and efficiency relative to paper-based methods. However, mobile data collection systems can hamper many standard quality assurance techniques due to the lack of a hardcopy backup of data. Consequently, mobile health data collection platforms have the potential to generate datasets that appear valid, but are susceptible to unidentified database design flaws, areas of miscomprehension by enumerators, and data recording errors. Objective We describe the design and evaluation of a strategy for estimating data error rates and assessing enumerator performance during electronic data collection, which we term “validation relaxation.” Validation relaxation involves the intentional omission of data validation features for select questions to allow for data recording errors to be committed, detected, and monitored. Methods We analyzed data collected during a cluster sample population survey in rural Liberia using an electronic data collection system (Open Data Kit). We first developed a classification scheme for types of detectable errors and validation alterations required to detect them. We then implemented the following validation relaxation techniques to enable data error conduct and detection: intentional redundancy, removal of “required” constraint, and illogical response combinations. This allowed for up to 11 identifiable errors to be made per survey. The error rate was defined as the total number of errors committed divided by the number of potential errors. We summarized crude error rates and estimated changes in error rates over time for both individuals and the entire program using logistic regression. Results The aggregate error rate was 1.60% (125/7817). Error rates did not differ significantly between enumerators (P=.51), but decreased for the cohort with increasing days of application use, from 2.3% at survey start (95% CI 1.8%-2.8%) to 0.6% at day 45 (95% CI 0.3%-0.9%; OR=0.969; P<.001). The highest error rate (84/618, 13.6%) occurred for an intentional redundancy question for a birthdate field, which was repeated in separate sections of the survey. We found low error rates (0.0% to 3.1%) for all other possible errors. Conclusions A strategy of removing validation rules on electronic data capture platforms can be used to create a set of detectable data errors, which can subsequently be used to assess group and individual enumerator error rates, their trends over time, and categories of data collection that require further training or additional quality control measures. This strategy may be particularly useful for identifying individual enumerators or systematic data errors that are responsive to enumerator training and is best applied to questions for which errors cannot be prevented through training or software design alone. Validation relaxation should be considered as a component of a holistic data quality assurance strategy. PMID:28821474

Validation Relaxation: A Quality Assurance Strategy for Electronic Data Collection.

PubMed

Kenny, Avi; Gordon, Nicholas; Griffiths, Thomas; Kraemer, John D; Siedner, Mark J

2017-08-18

The use of mobile devices for data collection in developing world settings is becoming increasingly common and may offer advantages in data collection quality and efficiency relative to paper-based methods. However, mobile data collection systems can hamper many standard quality assurance techniques due to the lack of a hardcopy backup of data. Consequently, mobile health data collection platforms have the potential to generate datasets that appear valid, but are susceptible to unidentified database design flaws, areas of miscomprehension by enumerators, and data recording errors. We describe the design and evaluation of a strategy for estimating data error rates and assessing enumerator performance during electronic data collection, which we term "validation relaxation." Validation relaxation involves the intentional omission of data validation features for select questions to allow for data recording errors to be committed, detected, and monitored. We analyzed data collected during a cluster sample population survey in rural Liberia using an electronic data collection system (Open Data Kit). We first developed a classification scheme for types of detectable errors and validation alterations required to detect them. We then implemented the following validation relaxation techniques to enable data error conduct and detection: intentional redundancy, removal of "required" constraint, and illogical response combinations. This allowed for up to 11 identifiable errors to be made per survey. The error rate was defined as the total number of errors committed divided by the number of potential errors. We summarized crude error rates and estimated changes in error rates over time for both individuals and the entire program using logistic regression. The aggregate error rate was 1.60% (125/7817). Error rates did not differ significantly between enumerators (P=.51), but decreased for the cohort with increasing days of application use, from 2.3% at survey start (95% CI 1.8%-2.8%) to 0.6% at day 45 (95% CI 0.3%-0.9%; OR=0.969; P<.001). The highest error rate (84/618, 13.6%) occurred for an intentional redundancy question for a birthdate field, which was repeated in separate sections of the survey. We found low error rates (0.0% to 3.1%) for all other possible errors. A strategy of removing validation rules on electronic data capture platforms can be used to create a set of detectable data errors, which can subsequently be used to assess group and individual enumerator error rates, their trends over time, and categories of data collection that require further training or additional quality control measures. This strategy may be particularly useful for identifying individual enumerators or systematic data errors that are responsive to enumerator training and is best applied to questions for which errors cannot be prevented through training or software design alone. Validation relaxation should be considered as a component of a holistic data quality assurance strategy. ©Avi Kenny, Nicholas Gordon, Thomas Griffiths, John D Kraemer, Mark J Siedner. Originally published in the Journal of Medical Internet Research (http://www.jmir.org), 18.08.2017.

On using summary statistics from an external calibration sample to correct for covariate measurement error.

PubMed

Guo, Ying; Little, Roderick J; McConnell, Daniel S

2012-01-01

Covariate measurement error is common in epidemiologic studies. Current methods for correcting measurement error with information from external calibration samples are insufficient to provide valid adjusted inferences. We consider the problem of estimating the regression of an outcome Y on covariates X and Z, where Y and Z are observed, X is unobserved, but a variable W that measures X with error is observed. Information about measurement error is provided in an external calibration sample where data on X and W (but not Y and Z) are recorded. We describe a method that uses summary statistics from the calibration sample to create multiple imputations of the missing values of X in the regression sample, so that the regression coefficients of Y on X and Z and associated standard errors can be estimated using simple multiple imputation combining rules, yielding valid statistical inferences under the assumption of a multivariate normal distribution. The proposed method is shown by simulation to provide better inferences than existing methods, namely the naive method, classical calibration, and regression calibration, particularly for correction for bias and achieving nominal confidence levels. We also illustrate our method with an example using linear regression to examine the relation between serum reproductive hormone concentrations and bone mineral density loss in midlife women in the Michigan Bone Health and Metabolism Study. Existing methods fail to adjust appropriately for bias due to measurement error in the regression setting, particularly when measurement error is substantial. The proposed method corrects this deficiency.