Assessing Principals' Quality Assurance Strategies in Osun State Secondary Schools, Nigeria

ERIC Educational Resources Information Center

Fasasi, Yunus Adebunmi; Oyeniran, Saheed

2014-01-01

This paper examined principals' quality assurance strategies in secondary schools in Osun State, Nigeria. The study adopted a descriptive survey research design. Stratified random sampling technique was used to select 10 male and 10 female principals, and 190 male and190 female teachers. "Secondary School Principal Quality Assurance…

Curriculum Review Evaluation on Entrepreneurial Education in Cross River State Higher Institutions

ERIC Educational Resources Information Center

Ambekeh, Udida Lucy

2013-01-01

This study investigated curriculum organization and delivery towards functional entrepreneurial education transformation of students in Higher Institutions in Cross River State -- Nigeria. To guide the conduct of this study, two research questions and one hypothesis were formulated. Proportionate stratified sampling technique was used in the…

Comparison of sampling strategies for object-based classification of urban vegetation from Very High Resolution satellite images

NASA Astrophysics Data System (ADS)

Rougier, Simon; Puissant, Anne; Stumpf, André; Lachiche, Nicolas

2016-09-01

Vegetation monitoring is becoming a major issue in the urban environment due to the services they procure and necessitates an accurate and up to date mapping. Very High Resolution satellite images enable a detailed mapping of the urban tree and herbaceous vegetation. Several supervised classifications with statistical learning techniques have provided good results for the detection of urban vegetation but necessitate a large amount of training data. In this context, this study proposes to investigate the performances of different sampling strategies in order to reduce the number of examples needed. Two windows based active learning algorithms from state-of-art are compared to a classical stratified random sampling and a third combining active learning and stratified strategies is proposed. The efficiency of these strategies is evaluated on two medium size French cities, Strasbourg and Rennes, associated to different datasets. Results demonstrate that classical stratified random sampling can in some cases be just as effective as active learning methods and that it should be used more frequently to evaluate new active learning methods. Moreover, the active learning strategies proposed in this work enables to reduce the computational runtime by selecting multiple windows at each iteration without increasing the number of windows needed.

Sensitivity of FIA Volume Estimates to Changes in Stratum Weights and Number of Strata

Treesearch

James A. Westfall; Michael Hoppus

2005-01-01

In the Northeast region, the USDA Forest Service Forest Inventory and Analysis (FIA) program utilizes stratified sampling techniques to improve the precision of population estimates. Recently, interpretation of aerial photographs was replaced with classified remotely sensed imagery to determine stratum weights and plot stratum assignments. However, stratum weights...

Primary Teacher Trainees Preparedness to Teach Science: A Gender Perspective

ERIC Educational Resources Information Center

Mutisya, Sammy M.

2015-01-01

The purpose of this study was to determine Primary Teacher Education (PTE) Trainees' perceptions regarding their preparedness to teach science in primary schools. A descriptive survey research design was used and stratified proportionate random sampling techniques used to select 177 males and 172 females. The study found out that more male trainee…

An Investigation on Secondary School Students' Attitude towards Science in Ogun State, Nigeria

ERIC Educational Resources Information Center

Sakariyau, A. O.; Taiwo, Michael O.; Ajagbe, Olalere W.

2016-01-01

The study investigated the attitudes of secondary school students towards science in Odeda Local Government Area of Ogun State, Nigeria. Two hundred senior secondary school students consisting of 84 males and 116 females were selected from five secondary schools using stratified random sampling techniques. A 20-item Attitude to Science…

Conflict Resolution Strategies in Non-Government Secondary Schools in Benue State, Nigeria

ERIC Educational Resources Information Center

Oboegbulem, Angie; Alfa, Idoko Alphonusu

2013-01-01

This study investigated perceived CRSs (conflict resolution strategies) for the resolution of conflicts in non-government secondary schools in Benue State, Nigeria. Three research questions and three hypotheses guided this study. Proportionate stratified random sampling technique was used in drawing 15% of the population which gave a total of 500…

Marital and Procreative Projections of Rural Louisiana Youth: A Historical Comparison.

ERIC Educational Resources Information Center

Smith, Kevin B.; Ohlendorf, George W.

Changes in marital and procreative projections among rural Louisiana high school youth between 1968 and 1972 were examined. In 1968 a proportionate, stratified, random cluster sampling technique was employed to secure data on seniors from 13 white and 7 black high schools. In 1972 public school integration and the establishment of private schools…

Winter bait stations as a multispecies survey tool

Treesearch

Lacy Robinson; Samuel A. Cushman; Michael K. Lucid

2017-01-01

Winter bait stations are becoming a commonly used technique for multispecies inventory and monitoring but a technical evaluation of their effectiveness is lacking. Bait stations have three components: carcass attractant, remote camera, and hair snare. Our 22,975 km2 mountainous study area was stratified with a 5 × 5 km sampling grid centered on northern Idaho and...

Demographic Determinants of Students Susceptibility to Peer Victimization in Secondary Schools in Osun State, Nigeria

ERIC Educational Resources Information Center

Adefunke, Ehindero Serifat

2015-01-01

This study examined age, sex, class and religion as determinants of students' susceptibility to peer victimization. One thousand five hundred students from 10 public secondary schools were selected by stratified sampling technique using class level as strata. A validated multi-dimensional peer victimization scale (MPVS) was used to collect data…

Students' and Human Rights Awareness in Secondary Schools' Environment in Delta State

ERIC Educational Resources Information Center

Akiri, Agharuwhe A.

2013-01-01

The paper reviewed the concept of human rights, possible origin and relevance to human society in general and the school system in particular. It evaluated people's level of awareness of these rights amongst students and teachers of secondary schools in Delta Central Senatorial District. The stratified random sampling technique was adopted to…

New Horizon of Spiritual Well-Being and Hope among Cancer Patients: A Psychological Aspect

ERIC Educational Resources Information Center

Liaquat, Sidra; Sultan, Sarwat; Hussain, Irshad

2013-01-01

The purpose of this study was to address the importance of spiritual well-being and hope among cancer patients diagnosed with its different stages. Through stratified sampling techniques, 120 cancer patients from four stages evenly divided into male and female participated in this study. Spiritual Well-being Scale (Paloutzian & Ellison, 1982)…

Computerized stratified random site-selection approaches for design of a ground-water-quality sampling network

USGS Publications Warehouse

Scott, J.C.

1990-01-01

Computer software was written to randomly select sites for a ground-water-quality sampling network. The software uses digital cartographic techniques and subroutines from a proprietary geographic information system. The report presents the approaches, computer software, and sample applications. It is often desirable to collect ground-water-quality samples from various areas in a study region that have different values of a spatial characteristic, such as land-use or hydrogeologic setting. A stratified network can be used for testing hypotheses about relations between spatial characteristics and water quality, or for calculating statistical descriptions of water-quality data that account for variations that correspond to the spatial characteristic. In the software described, a study region is subdivided into areal subsets that have a common spatial characteristic to stratify the population into several categories from which sampling sites are selected. Different numbers of sites may be selected from each category of areal subsets. A population of potential sampling sites may be defined by either specifying a fixed population of existing sites, or by preparing an equally spaced population of potential sites. In either case, each site is identified with a single category, depending on the value of the spatial characteristic of the areal subset in which the site is located. Sites are selected from one category at a time. One of two approaches may be used to select sites. Sites may be selected randomly, or the areal subsets in the category can be grouped into cells and sites selected randomly from each cell.

Jet-mixing of initially-stratified liquid-liquid pipe flows: experiments and numerical simulations

NASA Astrophysics Data System (ADS)

Wright, Stuart; Ibarra-Hernandes, Roberto; Xie, Zhihua; Markides, Christos; Matar, Omar

2016-11-01

Low pipeline velocities lead to stratification and so-called 'phase slip' in horizontal liquid-liquid flows due to differences in liquid densities and viscosities. Stratified flows have no suitable single point for sampling, from which average phase properties (e.g. fractions) can be established. Inline mixing, achieved by static mixers or jets in cross-flow (JICF), is often used to overcome liquid-liquid stratification by establishing unstable two-phase dispersions for sampling. Achieving dispersions in liquid-liquid pipeline flows using JICF is the subject of this experimental and modelling work. The experimental facility involves a matched refractive index liquid-liquid-solid system, featuring an ETFE test section, and experimental liquids which are silicone oil and a 51-wt% glycerol solution. The matching then allows the dispersed fluid phase fractions and velocity fields to be established through advanced optical techniques, namely PLIF (for phase) and PTV or PIV (for velocity fields). CFD codes using the volume of a fluid (VOF) method are then used to demonstrate JICF breakup and dispersion in stratified pipeline flows. A number of simple jet configurations are described and their dispersion effectiveness is compared with the experimental results. Funding from Cameron for Ph.D. studentship (SW) gratefully acknowledged.

A SWOT Analysis of Male and Female Students' Performance in Chemistry: A Comparative Study

ERIC Educational Resources Information Center

Ezeudu, Florence O.; Chiaha, Gertrude-Theresa Uzoamaka; Anazor, Lynda Chioma; Eze, Justina Uzoamaka; Omeke, Faith Chinwe

2015-01-01

The purpose of this study was to do a SWOT analysis and compare performances of male and female students in chemistry. Four research questions and four null hypotheses guided the study. Two boys', two girls' and two coeducational schools involving 1319 males and 1831 females, were selected by a stratified, deliberate sampling technique. A…

Outcomes of Parental Use of Psychological Aggression on Children: A Structural Model from Sri Lanka

ERIC Educational Resources Information Center

de Zoysa, Piyanjali; Newcombe, Peter A.; Rajapakse, Lalini

2010-01-01

The objective of this study was to explore the existence and, if so, the nature of the association between parental use of psychological aggression and psychological maladjustment in a 12-year-old Sri Lankan school population. A stratified random sampling technique was used to select 1,226 children from Colombo district schools. Three instruments,…

Recreation use of upper Pemigewasset and Swift River Drainages, New Hampshire

Treesearch

Ronald J. Glass; Gerald S. Walton

1995-01-01

In-stream recreation use of the upper Pemigewasset and Swift River Drainages was estimated by a technique based on modified, stratified sampling. Results are reported by category of stream segment, season, day of week, time of day, and activity. "Weekend and holiday" use exceeded weekday use during spring and fall, but weekdays had the heaviest use during the...

Estimates of recreational stream use in the White River drainage, Vermont

Treesearch

Ronald J. Glass; Gerald Walton; Herbert E. Echelberger; Herbert E. Echelberger

1992-01-01

An observation technique that incorporates Godified, stratified sampling was used to estimate in-stream recreation use in the White River Drainage in Vermont. Results were reported by season, day of week, time of day, kind of activity, and portion of stream. Summer had the highest use followed by spring and fall. Except in fall, weekends and holidays received...

Individual and Familial Correlates of Career Salience among Upwardly Mobile College Women. Final Report.

ERIC Educational Resources Information Center

Guttmacher, Mary Johnson

A case study was conducted using a sample of 271 women selected from a state college by a stratified random cluster technique that approximates proportional representation of women in all four classes and all college majors. The data source was an extensive questionnaire designed to measure the attitudes and behavior of interest. The major…

Self-Efficacy, Risk-Taking Behavior and Mental Health as Predictors of Personal Growth Initiative among University Undergraduates

ERIC Educational Resources Information Center

Ogunyemi, Ajibola O.; Mabekoje, Sesan Ola

2007-01-01

Introduction: This study sought to determine the combined and relative efficacy of self-efficacy, risk-taking behaviour and mental health on personal growth initiative of university undergraduates. Method: The expo-facto research design was used to conduct the study. Stratified random sampling technique was used to select 425 participants from 6…

Assesment of Perceived Academic and Incentive Needs of Senior Secondary School Biology Teachers in Kwara State, Nigeria

ERIC Educational Resources Information Center

Ahmed, Mulkah Adebisi; Moradeyo, Ismail; Abimbola, Isaac Olakanmi

2016-01-01

The study investigated the Assessment of perceived academic and incentive needs of senior secondary school biology teachers in Kwara State, Nigeria. Stratified random sampling technique was used to select two hundred and fifty (250) biology teachers from the three senatorial district of Kwara State. A questionnaire was prepared, validated and used…

A statistically valid method for using FIA plots to guide spectral class rejection in producing stratification maps

Treesearch

Michael L. Hoppus; Andrew J. Lister

2002-01-01

A Landsat TM classification method (iterative guided spectral class rejection) produced a forest cover map of southern West Virginia that provided the stratification layer for producing estimates of timberland area from Forest Service FIA ground plots using a stratified sampling technique. These same high quality and expensive FIA ground plots provided ground reference...

Public Perception of the Millennium Development Goals on Access to Safe Drinking Water in Cross River State, Nigeria

ERIC Educational Resources Information Center

Eni, David D.; Ojong, William M.

2014-01-01

This study evaluated the public perception of Millennium Development Goals (MDGs) of environmental sustainability with focus on the MDG target which has to do with reducing the proportion of people without access to safe drinking water in Cross River State, Nigeria. The stratified and systematic sampling techniques were adopted for the study,…

Teachers' Opinions on the Incorporation of Environmental Education in the Nigerian Primary School Curriculum

ERIC Educational Resources Information Center

Jekayinfa, Alice Arinlade; Yusuf, Abdul Raheem

2008-01-01

This paper presents the report of a research carried out in Kwara Sate of Nigeria to seek the opinions of teachers on the incorporation of Environmental Education (EE) in the Nigerian Primary School Curriculum. The descriptive survey method was employed for the study. 200 teachers were selected through stratified random sampling technique to cater…

Factors Associated with Nurses' Intention to Report Child Abuse: A National Survey of Taiwanese Nurses

ERIC Educational Resources Information Center

Feng, J.Y.; Levine, M.

2005-01-01

Objective:The objectives were to determine the experiences of Taiwanese nurses with a new child abuse reporting law and to assess attitudinal correlates of nurses' intention to report. Method: A stratified quota sampling technique was used to select registered nurses working in pediatric, psychiatric and emergency care units in Taiwan. A total of…

Monitoring and identification of spatiotemporal landscape changes in multiple remote sensing images by using a stratified conditional Latin hypercube sampling approach and geostatistical simulation.

PubMed

Lin, Yu-Pin; Chu, Hone-Jay; Huang, Yu-Long; Tang, Chia-Hsi; Rouhani, Shahrokh

2011-06-01

This study develops a stratified conditional Latin hypercube sampling (scLHS) approach for multiple, remotely sensed, normalized difference vegetation index (NDVI) images. The objective is to sample, monitor, and delineate spatiotemporal landscape changes, including spatial heterogeneity and variability, in a given area. The scLHS approach, which is based on the variance quadtree technique (VQT) and the conditional Latin hypercube sampling (cLHS) method, selects samples in order to delineate landscape changes from multiple NDVI images. The images are then mapped for calibration and validation by using sequential Gaussian simulation (SGS) with the scLHS selected samples. Spatial statistical results indicate that in terms of their statistical distribution, spatial distribution, and spatial variation, the statistics and variograms of the scLHS samples resemble those of multiple NDVI images more closely than those of cLHS and VQT samples. Moreover, the accuracy of simulated NDVI images based on SGS with scLHS samples is significantly better than that of simulated NDVI images based on SGS with cLHS samples and VQT samples, respectively. However, the proposed approach efficiently monitors the spatial characteristics of landscape changes, including the statistics, spatial variability, and heterogeneity of NDVI images. In addition, SGS with the scLHS samples effectively reproduces spatial patterns and landscape changes in multiple NDVI images.

Sources of Malaria Information among Pregnant Women in Ebonyi State and Implications for Malaria Health Education

ERIC Educational Resources Information Center

Amari-Omaka, Lois Nnenna; Obande-Ogbuinya, Nkiru Edith

2016-01-01

The purpose of this study was to determine sources of malaria information among pregnant women in Ebonyi state and implications for malaria education. The cross sectional research design was adopted and stratified sampling technique was used to select a total of five hundred and four (504) pregnant women from 12 hospitals in the state. A self…

A Comparative Study of Students' Access to and Utilization of Learning Resources in Selected Public and Private Universities in Southwest, Nigeria

ERIC Educational Resources Information Center

Lawal, B. O.; Viatonu, Olumuyiwa

2017-01-01

The study investigated students' access to and utilization of some learning resources in selected public and private universities in southwest Nigeria. Stratified random sampling technique was used to select 585 (295 public and 290 private) students from 12 (six public and six private) universities in southwest Nigeria. Two instruments--Cost and…

An improved algorithm of image processing technique for film thickness measurement in a horizontal stratified gas-liquid two-phase flow

NASA Astrophysics Data System (ADS)

Kuntoro, Hadiyan Yusuf; Hudaya, Akhmad Zidni; Dinaryanto, Okto; Majid, Akmal Irfan; Deendarlianto

2016-06-01

Due to the importance of the two-phase flow researches for the industrial safety analysis, many researchers developed various methods and techniques to study the two-phase flow phenomena on the industrial cases, such as in the chemical, petroleum and nuclear industries cases. One of the developing methods and techniques is image processing technique. This technique is widely used in the two-phase flow researches due to the non-intrusive capability to process a lot of visualization data which are contain many complexities. Moreover, this technique allows to capture direct-visual information data of the flow which are difficult to be captured by other methods and techniques. The main objective of this paper is to present an improved algorithm of image processing technique from the preceding algorithm for the stratified flow cases. The present algorithm can measure the film thickness (hL) of stratified flow as well as the geometrical properties of the interfacial waves with lower processing time and random-access memory (RAM) usage than the preceding algorithm. Also, the measurement results are aimed to develop a high quality database of stratified flow which is scanty. In the present work, the measurement results had a satisfactory agreement with the previous works.

An improved algorithm of image processing technique for film thickness measurement in a horizontal stratified gas-liquid two-phase flow

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

Kuntoro, Hadiyan Yusuf, E-mail: hadiyan.y.kuntoro@mail.ugm.ac.id; Majid, Akmal Irfan; Deendarlianto, E-mail: deendarlianto@ugm.ac.id

Due to the importance of the two-phase flow researches for the industrial safety analysis, many researchers developed various methods and techniques to study the two-phase flow phenomena on the industrial cases, such as in the chemical, petroleum and nuclear industries cases. One of the developing methods and techniques is image processing technique. This technique is widely used in the two-phase flow researches due to the non-intrusive capability to process a lot of visualization data which are contain many complexities. Moreover, this technique allows to capture direct-visual information data of the flow which are difficult to be captured by other methodsmore » and techniques. The main objective of this paper is to present an improved algorithm of image processing technique from the preceding algorithm for the stratified flow cases. The present algorithm can measure the film thickness (h{sub L}) of stratified flow as well as the geometrical properties of the interfacial waves with lower processing time and random-access memory (RAM) usage than the preceding algorithm. Also, the measurement results are aimed to develop a high quality database of stratified flow which is scanty. In the present work, the measurement results had a satisfactory agreement with the previous works.« less

An integrated study of earth resources in the state of California using remote sensing techniques

NASA Technical Reports Server (NTRS)

Colwell, R. N. (Principal Investigator)

1975-01-01

The author has identified the following significant results. A weighted stratified double sample design using hardcopy LANDSAT-1 and ground data was utilized in developmental studies for snow water content estimation. Study results gave a correlation coefficient of 0.80 between LANDSAT sample units estimates of snow water content and ground subsamples. A basin snow water content estimate allowable error was given as 1.00 percent at the 99 percent confidence level with the same budget level utilized in conventional snow surveys. Several evapotranspiration estimation models were selected for efficient application at each level of data to be sampled. An area estimation procedure for impervious surface types of differing impermeability adjacent to stream channels was developed. This technique employs a double sample of 1:125,000 color infrared hightflight transparency data with ground or large scale photography.

Computer-aided boundary delineation of agricultural lands

NASA Technical Reports Server (NTRS)

Cheng, Thomas D.; Angelici, Gary L.; Slye, Robert E.; Ma, Matt

1989-01-01

The National Agricultural Statistics Service of the United States Department of Agriculture (USDA) presently uses labor-intensive aerial photographic interpretation techniques to divide large geographical areas into manageable-sized units for estimating domestic crop and livestock production. Prototype software, the computer-aided stratification (CAS) system, was developed to automate the procedure, and currently runs on a Sun-based image processing system. With a background display of LANDSAT Thematic Mapper and United States Geological Survey Digital Line Graph data, the operator uses a cursor to delineate agricultural areas, called sampling units, which are assigned to strata of land-use and land-cover types. The resultant stratified sampling units are used as input into subsequent USDA sampling procedures. As a test, three counties in Missouri were chosen for application of the CAS procedures. Subsequent analysis indicates that CAS was five times faster in creating sampling units than the manual techniques were.

Number of pins in two-stage stratified sampling for estimating herbage yield

Treesearch

William G. O' Regan; C. Eugene Conrad

1975-01-01

In a two-stage stratified procedure for sampling herbage yield, plots are stratified by a pin frame in stage one, and clipped. In stage two, clippings from selected plots are sorted, dried, and weighed. Sample size and distribution of plots between the two stages are determined by equations. A way to compute the effect of number of pins on the variance of estimated...

FDTD scattered field formulation for scatterers in stratified dispersive media.

PubMed

Olkkonen, Juuso

2010-03-01

We introduce a simple scattered field (SF) technique that enables finite difference time domain (FDTD) modeling of light scattering from dispersive objects residing in stratified dispersive media. The introduced SF technique is verified against the total field scattered field (TFSF) technique. As an application example, we study surface plasmon polariton enhanced light transmission through a 100 nm wide slit in a silver film.

Guidance and Counselling: What Is the Level of Human and Physical Resource Preparedness in Providing Effective Services in Secondary Schools in Bureti Sub County, Kericho County, Kenya?

ERIC Educational Resources Information Center

Cheruiyot, David Kipkorir; Orodho, John Aluko

2015-01-01

The gist of this study was to examine the human and resource preparedness to provide effective guidance and counselling (G&C) services in secondary schools in Bureti Sub County, Kericho County, Kenya. The study used combinations of descriptive survey and correlation research designs. Stratified sampling technique was employed to select 20…

Sampling Methods in Cardiovascular Nursing Research: An Overview.

PubMed

Kandola, Damanpreet; Banner, Davina; O'Keefe-McCarthy, Sheila; Jassal, Debbie

2014-01-01

Cardiovascular nursing research covers a wide array of topics from health services to psychosocial patient experiences. The selection of specific participant samples is an important part of the research design and process. The sampling strategy employed is of utmost importance to ensure that a representative sample of participants is chosen. There are two main categories of sampling methods: probability and non-probability. Probability sampling is the random selection of elements from the population, where each element of the population has an equal and independent chance of being included in the sample. There are five main types of probability sampling including simple random sampling, systematic sampling, stratified sampling, cluster sampling, and multi-stage sampling. Non-probability sampling methods are those in which elements are chosen through non-random methods for inclusion into the research study and include convenience sampling, purposive sampling, and snowball sampling. Each approach offers distinct advantages and disadvantages and must be considered critically. In this research column, we provide an introduction to these key sampling techniques and draw on examples from the cardiovascular research. Understanding the differences in sampling techniques may aid nurses in effective appraisal of research literature and provide a reference pointfor nurses who engage in cardiovascular research.

Distribution-Preserving Stratified Sampling for Learning Problems.

PubMed

Cervellera, Cristiano; Maccio, Danilo

2017-06-09

The need for extracting a small sample from a large amount of real data, possibly streaming, arises routinely in learning problems, e.g., for storage, to cope with computational limitations, obtain good training/test/validation sets, and select minibatches for stochastic gradient neural network training. Unless we have reasons to select the samples in an active way dictated by the specific task and/or model at hand, it is important that the distribution of the selected points is as similar as possible to the original data. This is obvious for unsupervised learning problems, where the goal is to gain insights on the distribution of the data, but it is also relevant for supervised problems, where the theory explains how the training set distribution influences the generalization error. In this paper, we analyze the technique of stratified sampling from the point of view of distances between probabilities. This allows us to introduce an algorithm, based on recursive binary partition of the input space, aimed at obtaining samples that are distributed as much as possible as the original data. A theoretical analysis is proposed, proving the (greedy) optimality of the procedure together with explicit error bounds. An adaptive version of the algorithm is also introduced to cope with streaming data. Simulation tests on various data sets and different learning tasks are also provided.

Accuracy Sampling Design Bias on Coarse Spatial Resolution Land Cover Data in the Great Lakes Region (United States and Canada)

EPA Science Inventory

A number of articles have investigated the impact of sampling design on remotely sensed landcover accuracy estimates. Gong and Howarth (1990) found significant differences for Kappa accuracy values when comparing purepixel sampling, stratified random sampling, and stratified sys...

Financing Adult Education: How Adequate Are Current Sources in Facilitating Access and Participation in Centres in Murang'a South Sub-County, Murang'a County, Kenya?

ERIC Educational Resources Information Center

Maina, Ndonga James; Orodho, John Aluko

2016-01-01

The thrust of this study was to examine the level of adequacy of current sources in facilitating access and participation in adult education centres in Murang'a South Sub-County, Murang'a County, Kenya. The study adopted the descriptive survey design. Combinations of purposive and stratified random sampling techniques were used to select 82…

A stratified random survey of the proportion of poor quality oral artesunate sold at medicine outlets in the Lao PDR – implications for therapeutic failure and drug resistance

PubMed Central

Sengaloundeth, Sivong; Green, Michael D; Fernández, Facundo M; Manolin, Ot; Phommavong, Khamlieng; Insixiengmay, Vongsavanh; Hampton, Christina Y; Nyadong, Leonard; Mildenhall, Dallas C; Hostetler, Dana; Khounsaknalath, Lamphet; Vongsack, Latsamy; Phompida, Samlane; Vanisaveth, Viengxay; Syhakhang, Lamphone; Newton, Paul N

2009-01-01

Background Counterfeit oral artesunate has been a major public health problem in mainland SE Asia, impeding malaria control. A countrywide stratified random survey was performed to determine the availability and quality of oral artesunate in pharmacies and outlets (shops selling medicines) in the Lao PDR (Laos). Methods In 2003, 'mystery' shoppers were asked to buy artesunate tablets from 180 outlets in 12 of the 18 Lao provinces. Outlets were selected using stratified random sampling by investigators not involved in sampling. Samples were analysed for packaging characteristics, by the Fast Red Dye test, high-performance liquid chromatography (HPLC), mass spectrometry (MS), X-ray diffractometry and pollen analysis. Results Of 180 outlets sampled, 25 (13.9%) sold oral artesunate. Outlets selling artesunate were more commonly found in the more malarious southern Laos. Of the 25 outlets, 22 (88%; 95%CI 68–97%) sold counterfeit artesunate, as defined by packaging and chemistry. No artesunate was detected in the counterfeits by any of the chemical analysis techniques and analysis of the packaging demonstrated seven different counterfeit types. There was complete agreement between the Fast Red dye test, HPLC and MS analysis. A wide variety of wrong active ingredients were found by MS. Of great concern, 4/27 (14.8%) fakes contained detectable amounts of artemisinin (0.26–115.7 mg/tablet). Conclusion This random survey confirms results from previous convenience surveys that counterfeit artesunate is a severe public health problem. The presence of artemisinin in counterfeits may encourage malaria resistance to artemisinin derivatives. With increasing accessibility of artemisinin-derivative combination therapy (ACT) in Laos, the removal of artesunate monotherapy from pharmacies may be an effective intervention. PMID:19638225

A stratified random survey of the proportion of poor quality oral artesunate sold at medicine outlets in the Lao PDR - implications for therapeutic failure and drug resistance.

PubMed

Sengaloundeth, Sivong; Green, Michael D; Fernández, Facundo M; Manolin, Ot; Phommavong, Khamlieng; Insixiengmay, Vongsavanh; Hampton, Christina Y; Nyadong, Leonard; Mildenhall, Dallas C; Hostetler, Dana; Khounsaknalath, Lamphet; Vongsack, Latsamy; Phompida, Samlane; Vanisaveth, Viengxay; Syhakhang, Lamphone; Newton, Paul N

2009-07-28

Counterfeit oral artesunate has been a major public health problem in mainland SE Asia, impeding malaria control. A countrywide stratified random survey was performed to determine the availability and quality of oral artesunate in pharmacies and outlets (shops selling medicines) in the Lao PDR (Laos). In 2003, 'mystery' shoppers were asked to buy artesunate tablets from 180 outlets in 12 of the 18 Lao provinces. Outlets were selected using stratified random sampling by investigators not involved in sampling. Samples were analysed for packaging characteristics, by the Fast Red Dye test, high-performance liquid chromatography (HPLC), mass spectrometry (MS), X-ray diffractometry and pollen analysis. Of 180 outlets sampled, 25 (13.9%) sold oral artesunate. Outlets selling artesunate were more commonly found in the more malarious southern Laos. Of the 25 outlets, 22 (88%; 95%CI 68-97%) sold counterfeit artesunate, as defined by packaging and chemistry. No artesunate was detected in the counterfeits by any of the chemical analysis techniques and analysis of the packaging demonstrated seven different counterfeit types. There was complete agreement between the Fast Red dye test, HPLC and MS analysis. A wide variety of wrong active ingredients were found by MS. Of great concern, 4/27 (14.8%) fakes contained detectable amounts of artemisinin (0.26-115.7 mg/tablet). This random survey confirms results from previous convenience surveys that counterfeit artesunate is a severe public health problem. The presence of artemisinin in counterfeits may encourage malaria resistance to artemisinin derivatives. With increasing accessibility of artemisinin-derivative combination therapy (ACT) in Laos, the removal of artesunate monotherapy from pharmacies may be an effective intervention.

The use of single-date MODIS imagery for estimating large-scale urban impervious surface fraction with spectral mixture analysis and machine learning techniques

NASA Astrophysics Data System (ADS)

Deng, Chengbin; Wu, Changshan

2013-12-01

Urban impervious surface information is essential for urban and environmental applications at the regional/national scales. As a popular image processing technique, spectral mixture analysis (SMA) has rarely been applied to coarse-resolution imagery due to the difficulty of deriving endmember spectra using traditional endmember selection methods, particularly within heterogeneous urban environments. To address this problem, we derived endmember signatures through a least squares solution (LSS) technique with known abundances of sample pixels, and integrated these endmember signatures into SMA for mapping large-scale impervious surface fraction. In addition, with the same sample set, we carried out objective comparative analyses among SMA (i.e. fully constrained and unconstrained SMA) and machine learning (i.e. Cubist regression tree and Random Forests) techniques. Analysis of results suggests three major conclusions. First, with the extrapolated endmember spectra from stratified random training samples, the SMA approaches performed relatively well, as indicated by small MAE values. Second, Random Forests yields more reliable results than Cubist regression tree, and its accuracy is improved with increased sample sizes. Finally, comparative analyses suggest a tentative guide for selecting an optimal approach for large-scale fractional imperviousness estimation: unconstrained SMA might be a favorable option with a small number of samples, while Random Forests might be preferred if a large number of samples are available.

Sampling estimators of total mill receipts for use in timber product output studies

Treesearch

John P. Brown; Richard G. Oderwald

2012-01-01

Data from the 2001 timber product output study for Georgia was explored to determine new methods for stratifying mills and finding suitable sampling estimators. Estimators for roundwood receipts totals comprised several types: simple random sample, ratio, stratified sample, and combined ratio. Two stratification methods were examined: the Dalenius-Hodges (DH) square...

Impact of Jos Crises on Pattern of Students/Teachers' Population in Schools and Its Implication on the Quality of Teaching and Peaceful Co-Existence in Nigeria

ERIC Educational Resources Information Center

Jacob, Sunday

2015-01-01

This study examined the pattern of students/teachers' population in schools as a result of the crises witnessed in Jos and its consequences on quality of teaching as well as peaceful living in Jos. Stratified simple random sampling technique was used to select the 18 schools that were used for this study. Questionnaire was used to collect…

Comparison of Self-Efficacy and Self-Regulation between the Students with School Refusal Behavior (SRB) and the Students without (SRB), and the Relationships of These Variables to Academic Performance

ERIC Educational Resources Information Center

Khanehkeshi, Ali; Ahmedi, Farahnaz Azizi Tas

2013-01-01

The purpose of this study was to compare self-efficacy and self-regulation between the students with SRB and students with NSRB, and the relationship of these variables to academic performance. Using a random stratified sampling technique 60 girl students who had school refusal behavior (SRB) and 60 of students without SRB were selected from 8…

Scan-stratified case-control sampling for modeling blood-brain barrier integrity in multiple sclerosis.

PubMed

Pomann, Gina-Maria; Sweeney, Elizabeth M; Reich, Daniel S; Staicu, Ana-Maria; Shinohara, Russell T

2015-09-10

Multiple sclerosis (MS) is an immune-mediated neurological disease that causes morbidity and disability. In patients with MS, the accumulation of lesions in the white matter of the brain is associated with disease progression and worse clinical outcomes. Breakdown of the blood-brain barrier in newer lesions is indicative of more active disease-related processes and is a primary outcome considered in clinical trials of treatments for MS. Such abnormalities in active MS lesions are evaluated in vivo using contrast-enhanced structural MRI, during which patients receive an intravenous infusion of a costly magnetic contrast agent. In some instances, the contrast agents can have toxic effects. Recently, local image regression techniques have been shown to have modest performance for assessing the integrity of the blood-brain barrier based on imaging without contrast agents. These models have centered on the problem of cross-sectional classification in which patients are imaged at a single study visit and pre-contrast images are used to predict post-contrast imaging. In this paper, we extend these methods to incorporate historical imaging information, and we find the proposed model to exhibit improved performance. We further develop scan-stratified case-control sampling techniques that reduce the computational burden of local image regression models, while respecting the low proportion of the brain that exhibits abnormal vascular permeability. Copyright © 2015 John Wiley & Sons, Ltd.

Sampling designs for HIV molecular epidemiology with application to Honduras.

PubMed

Shepherd, Bryan E; Rossini, Anthony J; Soto, Ramon Jeremias; De Rivera, Ivette Lorenzana; Mullins, James I

2005-11-01

Proper sampling is essential to characterize the molecular epidemiology of human immunodeficiency virus (HIV). HIV sampling frames are difficult to identify, so most studies use convenience samples. We discuss statistically valid and feasible sampling techniques that overcome some of the potential for bias due to convenience sampling and ensure better representation of the study population. We employ a sampling design called stratified cluster sampling. This first divides the population into geographical and/or social strata. Within each stratum, a population of clusters is chosen from groups, locations, or facilities where HIV-positive individuals might be found. Some clusters are randomly selected within strata and individuals are randomly selected within clusters. Variation and cost help determine the number of clusters and the number of individuals within clusters that are to be sampled. We illustrate the approach through a study designed to survey the heterogeneity of subtype B strains in Honduras.

[Comparison study on sampling methods of Oncomelania hupensis snail survey in marshland schistosomiasis epidemic areas in China].

PubMed

An, Zhao; Wen-Xin, Zhang; Zhong, Yao; Yu-Kuan, Ma; Qing, Liu; Hou-Lang, Duan; Yi-di, Shang

2016-06-29

To optimize and simplify the survey method of Oncomelania hupensis snail in marshland endemic region of schistosomiasis and increase the precision, efficiency and economy of the snail survey. A quadrate experimental field was selected as the subject of 50 m×50 m size in Chayegang marshland near Henghu farm in the Poyang Lake region and a whole-covered method was adopted to survey the snails. The simple random sampling, systematic sampling and stratified random sampling methods were applied to calculate the minimum sample size, relative sampling error and absolute sampling error. The minimum sample sizes of the simple random sampling, systematic sampling and stratified random sampling methods were 300, 300 and 225, respectively. The relative sampling errors of three methods were all less than 15%. The absolute sampling errors were 0.221 7, 0.302 4 and 0.047 8, respectively. The spatial stratified sampling with altitude as the stratum variable is an efficient approach of lower cost and higher precision for the snail survey.

Interactive boundary delineation of agricultural lands using graphics workstations

NASA Technical Reports Server (NTRS)

Cheng, Thomas D.; Angelici, Gary L.; Slye, Robert E.; Ma, Matt

1992-01-01

A review is presented of the computer-assisted stratification and sampling (CASS) system developed to delineate the boundaries of sample units for survey procedures. CASS stratifies the sampling units by land-cover and land-use type, employing image-processing software and hardware. This procedure generates coverage areas and the boundaries of stratified sampling units that are utilized for subsequent sampling procedures from which agricultural statistics are developed.

The multicategory case of the sequential Bayesian pixel selection and estimation procedure

NASA Technical Reports Server (NTRS)

Pore, M. D.; Dennis, T. B. (Principal Investigator)

1980-01-01

A Bayesian technique for stratified proportion estimation and a sampling based on minimizing the mean squared error of this estimator were developed and tested on LANDSAT multispectral scanner data using the beta density function to model the prior distribution in the two-class case. An extention of this procedure to the k-class case is considered. A generalization of the beta function is shown to be a density function for the general case which allows the procedure to be extended.

Design of dry sand soil stratified sampler

NASA Astrophysics Data System (ADS)

Li, Erkang; Chen, Wei; Feng, Xiao; Liao, Hongbo; Liang, Xiaodong

2018-04-01

This paper presents a design of a stratified sampler for dry sand soil, which can be used for stratified sampling of loose sand under certain conditions. Our group designed the mechanical structure of a portable, single - person, dry sandy soil stratified sampler. We have set up a mathematical model for the sampler. It lays the foundation for further development of design research.

Forest resource inventory assessment in Gunung Rara Forest Reserve, Sabah, using stratified field sampling

Treesearch

Kamaruzaman Jusoff

2000-01-01

The objective of this paper is to assess the current timber volume by stratified sampling on a proposed plantation area. The study area is located in Gunung Rara Forest Reserve in the district of Tawau, Sabah, Malaysia.

Differences in Mathematics Teachers' Perceived Preparedness to Demonstrate Competence in Secondary School Mathematics Content by Teacher Characteristics

ERIC Educational Resources Information Center

Ng'eno, J. K.; Chesimet, M. C.

2016-01-01

A sample of 300 mathematics teachers drawn from a population of 1500 participated in this study. The participants were selected using systematic random sampling and stratified random sampling (stratified by qualification and gender). The data was collected using self-report questionnaires for mathematics teachers. One tool was used to collect…

Differentials in colostrum feeding among lactating women of block RS Pura of J and K: A lesson for nursing practice.

PubMed

Raina, Sunil Kumar; Mengi, Vijay; Singh, Gurdeep

2012-07-01

Breast feeding is universally and traditionally practicised in India. Experts advocate breast feeding as the best method of feeding young infants. To assess the role of various factors in determining colostrum feeding in block R. S. Pura of district Jammu. A stratified two-stage design with villages as the primary sampling unit and lactating mothers as secondary sampling unit. Villages were divided into different clusters on the basis of population and sampling units were selected by a simple random technique. Breastfeeding is almost universal in R. S. Pura. Differentials in discarding the first milk were not found to be important among various socioeconomic groups and the phenomenon appeared more general than specific.

A comparison of selection at list time and time-stratified sampling for estimating suspended sediment loads

Treesearch

Robert B. Thomas; Jack Lewis

1993-01-01

Time-stratified sampling of sediment for estimating suspended load is introduced and compared to selection at list time (SALT) sampling. Both methods provide unbiased estimates of load and variance. The magnitude of the variance of the two methods is compared using five storm populations of suspended sediment flux derived from turbidity data. Under like conditions,...

Stemflow estimation in a redwood forest using model-based stratified random sampling

Treesearch

Jack Lewis

2003-01-01

Model-based stratified sampling is illustrated by a case study of stemflow volume in a redwood forest. The approach is actually a model-assisted sampling design in which auxiliary information (tree diameter) is utilized in the design of stratum boundaries to optimize the efficiency of a regression or ratio estimator. The auxiliary information is utilized in both the...

Group investigation with scientific approach in mathematics learning

NASA Astrophysics Data System (ADS)

Indarti, D.; Mardiyana; Pramudya, I.

2018-03-01

The aim of this research is to find out the effect of learning model toward mathematics achievement. This research is quasi-experimental research. The population of research is all VII grade students of Karanganyar regency in the academic year of 2016/2017. The sample of this research was taken using stratified cluster random sampling technique. Data collection was done based on mathematics achievement test. The data analysis technique used one-way ANOVA following the normality test with liliefors method and homogeneity test with Bartlett method. The results of this research is the mathematics learning using Group Investigation learning model with scientific approach produces the better mathematics learning achievement than learning with conventional model on material of quadrilateral. Group Investigation learning model with scientific approach can be used by the teachers in mathematics learning, especially in the material of quadrilateral, which is can improve the mathematics achievement.

Geospatial techniques for developing a sampling frame of watersheds across a region

USGS Publications Warehouse

Gresswell, Robert E.; Bateman, Douglas S.; Lienkaemper, George; Guy, T.J.

2004-01-01

Current land-management decisions that affect the persistence of native salmonids are often influenced by studies of individual sites that are selected based on judgment and convenience. Although this approach is useful for some purposes, extrapolating results to areas that were not sampled is statistically inappropriate because the sampling design is usually biased. Therefore, in recent investigations of coastal cutthroat trout (Oncorhynchus clarki clarki) located above natural barriers to anadromous salmonids, we used a methodology for extending the statistical scope of inference. The purpose of this paper is to apply geospatial tools to identify a population of watersheds and develop a probability-based sampling design for coastal cutthroat trout in western Oregon, USA. The population of mid-size watersheds (500-5800 ha) west of the Cascade Range divide was derived from watershed delineations based on digital elevation models. Because a database with locations of isolated populations of coastal cutthroat trout did not exist, a sampling frame of isolated watersheds containing cutthroat trout had to be developed. After the sampling frame of watersheds was established, isolated watersheds with coastal cutthroat trout were stratified by ecoregion and erosion potential based on dominant bedrock lithology (i.e., sedimentary and igneous). A stratified random sample of 60 watersheds was selected with proportional allocation in each stratum. By comparing watershed drainage areas of streams in the general population to those in the sampling frame and the resulting sample (n = 60), we were able to evaluate the how representative the subset of watersheds was in relation to the population of watersheds. Geospatial tools provided a relatively inexpensive means to generate the information necessary to develop a statistically robust, probability-based sampling design.

Sampling Strategies for Evaluating the Rate of Adventitious Transgene Presence in Non-Genetically Modified Crop Fields.

PubMed

Makowski, David; Bancal, Rémi; Bensadoun, Arnaud; Monod, Hervé; Messéan, Antoine

2017-09-01

According to E.U. regulations, the maximum allowable rate of adventitious transgene presence in non-genetically modified (GM) crops is 0.9%. We compared four sampling methods for the detection of transgenic material in agricultural non-GM maize fields: random sampling, stratified sampling, random sampling + ratio reweighting, random sampling + regression reweighting. Random sampling involves simply sampling maize grains from different locations selected at random from the field concerned. The stratified and reweighting sampling methods make use of an auxiliary variable corresponding to the output of a gene-flow model (a zero-inflated Poisson model) simulating cross-pollination as a function of wind speed, wind direction, and distance to the closest GM maize field. With the stratified sampling method, an auxiliary variable is used to define several strata with contrasting transgene presence rates, and grains are then sampled at random from each stratum. With the two methods involving reweighting, grains are first sampled at random from various locations within the field, and the observations are then reweighted according to the auxiliary variable. Data collected from three maize fields were used to compare the four sampling methods, and the results were used to determine the extent to which transgene presence rate estimation was improved by the use of stratified and reweighting sampling methods. We found that transgene rate estimates were more accurate and that substantially smaller samples could be used with sampling strategies based on an auxiliary variable derived from a gene-flow model. © 2017 Society for Risk Analysis.

Catholic High Schools and Their Finances. 1986.

ERIC Educational Resources Information Center

Augenstein, John J.

This report is based on a randomly selected and stratified sample of 208 United States Catholic high schools. The sample was stratified by governance (diocesan, parochial/interparochial, and private); five categories of enrollment; and six regions. Data are compared with an earlier study, "The Catholic High School: A National Portrait" and show…

Emerging Techniques in Stratified Designs and Continuous Gradients for Tissue Engineering of Interfaces

PubMed Central

Dormer, Nathan H.; Berkland, Cory J.; Detamore, Michael S.

2013-01-01

Interfacial tissue engineering is an emerging branch of regenerative medicine, where engineers are faced with developing methods for the repair of one or many functional tissue systems simultaneously. Early and recent solutions for complex tissue formation have utilized stratified designs, where scaffold formulations are segregated into two or more layers, with discrete changes in physical or chemical properties, mimicking a corresponding number of interfacing tissue types. This method has brought forth promising results, along with a myriad of regenerative techniques. The latest designs, however, are employing “continuous gradients” in properties, where there is no discrete segregation between scaffold layers. This review compares the methods and applications of recent stratified approaches to emerging continuously graded methods. PMID:20411333

Adjusting for multiple prognostic factors in the analysis of randomised trials

PubMed Central

2013-01-01

Background When multiple prognostic factors are adjusted for in the analysis of a randomised trial, it is unclear (1) whether it is necessary to account for each of the strata, formed by all combinations of the prognostic factors (stratified analysis), when randomisation has been balanced within each stratum (stratified randomisation), or whether adjusting for the main effects alone will suffice, and (2) the best method of adjustment in terms of type I error rate and power, irrespective of the randomisation method. Methods We used simulation to (1) determine if a stratified analysis is necessary after stratified randomisation, and (2) to compare different methods of adjustment in terms of power and type I error rate. We considered the following methods of analysis: adjusting for covariates in a regression model, adjusting for each stratum using either fixed or random effects, and Mantel-Haenszel or a stratified Cox model depending on outcome. Results Stratified analysis is required after stratified randomisation to maintain correct type I error rates when (a) there are strong interactions between prognostic factors, and (b) there are approximately equal number of patients in each stratum. However, simulations based on real trial data found that type I error rates were unaffected by the method of analysis (stratified vs unstratified), indicating these conditions were not met in real datasets. Comparison of different analysis methods found that with small sample sizes and a binary or time-to-event outcome, most analysis methods lead to either inflated type I error rates or a reduction in power; the lone exception was a stratified analysis using random effects for strata, which gave nominal type I error rates and adequate power. Conclusions It is unlikely that a stratified analysis is necessary after stratified randomisation except in extreme scenarios. Therefore, the method of analysis (accounting for the strata, or adjusting only for the covariates) will not generally need to depend on the method of randomisation used. Most methods of analysis work well with large sample sizes, however treating strata as random effects should be the analysis method of choice with binary or time-to-event outcomes and a small sample size. PMID:23898993

Health status of hotel workers with special reference to high risk practices and STDs.

PubMed

Pawar, A T; Kakrani, V A

2007-01-01

A cross sectional study was conducted on health status of hotel workers of Pune city. Out of estimated 1000 hotel workers 516 were selected by stratified random sampling technique. The study revealed that 71.5% hotel workers were suffering from one or other type of morbid condition. Anemia was the commonest morbidity with prevalence of 40.3%. 187 (36.2%) of hotel workers had extramarital sexual relations. A total of 77 (14.9%) hotel workers were having STDs at the time of study.

Report for Colorado: Background & Visuals, Math 2005. The Nation's Report Card

ERIC Educational Resources Information Center

Sandoval, Pam A.

2005-01-01

The National Assessment of Educational Progress (NAEP) 2005 assessment was administered to a stratified random sample of fourth-, eighth-, and twelfth-graders at the national level and to a stratified random sample of fourth- and eighth-graders at the state level. The Mathematics Framework for NAEP was revised in 1996 and again in 2005. The new…

Estimation of population mean in the presence of measurement error and non response under stratified random sampling

PubMed Central

Shabbir, Javid

2018-01-01

In the present paper we propose an improved class of estimators in the presence of measurement error and non-response under stratified random sampling for estimating the finite population mean. The theoretical and numerical studies reveal that the proposed class of estimators performs better than other existing estimators. PMID:29401519

Composition, biomass and structure of mangroves within the Zambezi River Delta

Treesearch

Carl C. Trettin; Christina E. Stringer; Stan Zarnoch

2015-01-01

We used a stratified random sampling design to inventory the mangrove vegetation within the Zambezi River Delta, Mozambique, to provide a basis for estimating biomass pools. We used canopy height, derived from remote sensing data, to stratify the inventory area, and then applied a spatial decision support system to objectively allocate sample plots among five...

Coniferous forest classification and inventory using Landsat and digital terrain data

NASA Technical Reports Server (NTRS)

Franklin, J.; Logan, T. L.; Woodcock, C. E.; Strahler, A. H.

1986-01-01

Machine-processing techniques were used in a Forest Classification and Inventory System (FOCIS) procedure to extract and process tonal, textural, and terrain information from registered Landsat multispectral and digital terrain data. Using FOCIS as a basis for stratified sampling, the softwood timber volumes of the Klamath National Forest and Eldorado National Forest were estimated within standard errors of 4.8 and 4.0 percent, respectively. The accuracy of these large-area inventories is comparable to the accuracy yielded by use of conventional timber inventory methods, but, because of automation, the FOCIS inventories are more rapid (9-12 months compared to 2-3 years for conventional manual photointerpretation, map compilation and drafting, field sampling, and data processing) and are less costly.

Quasi-Likelihood Techniques in a Logistic Regression Equation for Identifying Simulium damnosum s.l. Larval Habitats Intra-cluster Covariates in Togo.

PubMed

Jacob, Benjamin G; Novak, Robert J; Toe, Laurent; Sanfo, Moussa S; Afriyie, Abena N; Ibrahim, Mohammed A; Griffith, Daniel A; Unnasch, Thomas R

2012-01-01

The standard methods for regression analyses of clustered riverine larval habitat data of Simulium damnosum s.l. a major black-fly vector of Onchoceriasis, postulate models relating observational ecological-sampled parameter estimators to prolific habitats without accounting for residual intra-cluster error correlation effects. Generally, this correlation comes from two sources: (1) the design of the random effects and their assumed covariance from the multiple levels within the regression model; and, (2) the correlation structure of the residuals. Unfortunately, inconspicuous errors in residual intra-cluster correlation estimates can overstate precision in forecasted S.damnosum s.l. riverine larval habitat explanatory attributes regardless how they are treated (e.g., independent, autoregressive, Toeplitz, etc). In this research, the geographical locations for multiple riverine-based S. damnosum s.l. larval ecosystem habitats sampled from 2 pre-established epidemiological sites in Togo were identified and recorded from July 2009 to June 2010. Initially the data was aggregated into proc genmod. An agglomerative hierarchical residual cluster-based analysis was then performed. The sampled clustered study site data was then analyzed for statistical correlations using Monthly Biting Rates (MBR). Euclidean distance measurements and terrain-related geomorphological statistics were then generated in ArcGIS. A digital overlay was then performed also in ArcGIS using the georeferenced ground coordinates of high and low density clusters stratified by Annual Biting Rates (ABR). This data was overlain onto multitemporal sub-meter pixel resolution satellite data (i.e., QuickBird 0.61m wavbands ). Orthogonal spatial filter eigenvectors were then generated in SAS/GIS. Univariate and non-linear regression-based models (i.e., Logistic, Poisson and Negative Binomial) were also employed to determine probability distributions and to identify statistically significant parameter estimators from the sampled data. Thereafter, Durbin-Watson test statistics were used to test the null hypothesis that the regression residuals were not autocorrelated against the alternative that the residuals followed an autoregressive process in AUTOREG. Bayesian uncertainty matrices were also constructed employing normal priors for each of the sampled estimators in PROC MCMC. The residuals revealed both spatially structured and unstructured error effects in the high and low ABR-stratified clusters. The analyses also revealed that the estimators, levels of turbidity and presence of rocks were statistically significant for the high-ABR-stratified clusters, while the estimators distance between habitats and floating vegetation were important for the low-ABR-stratified cluster. Varying and constant coefficient regression models, ABR- stratified GIS-generated clusters, sub-meter resolution satellite imagery, a robust residual intra-cluster diagnostic test, MBR-based histograms, eigendecomposition spatial filter algorithms and Bayesian matrices can enable accurate autoregressive estimation of latent uncertainity affects and other residual error probabilities (i.e., heteroskedasticity) for testing correlations between georeferenced S. damnosum s.l. riverine larval habitat estimators. The asymptotic distribution of the resulting residual adjusted intra-cluster predictor error autocovariate coefficients can thereafter be established while estimates of the asymptotic variance can lead to the construction of approximate confidence intervals for accurately targeting productive S. damnosum s.l habitats based on spatiotemporal field-sampled count data.

Reaching the Hard-to-Reach: A Probability Sampling Method for Assessing Prevalence of Driving under the Influence after Drinking in Alcohol Outlets

PubMed Central

De Boni, Raquel; do Nascimento Silva, Pedro Luis; Bastos, Francisco Inácio; Pechansky, Flavio; de Vasconcellos, Mauricio Teixeira Leite

2012-01-01

Drinking alcoholic beverages in places such as bars and clubs may be associated with harmful consequences such as violence and impaired driving. However, methods for obtaining probabilistic samples of drivers who drink at these places remain a challenge – since there is no a priori information on this mobile population – and must be continually improved. This paper describes the procedures adopted in the selection of a population-based sample of drivers who drank at alcohol selling outlets in Porto Alegre, Brazil, which we used to estimate the prevalence of intention to drive under the influence of alcohol. The sampling strategy comprises a stratified three-stage cluster sampling: 1) census enumeration areas (CEA) were stratified by alcohol outlets (AO) density and sampled with probability proportional to the number of AOs in each CEA; 2) combinations of outlets and shifts (COS) were stratified by prevalence of alcohol-related traffic crashes and sampled with probability proportional to their squared duration in hours; and, 3) drivers who drank at the selected COS were stratified by their intention to drive and sampled using inverse sampling. Sample weights were calibrated using a post-stratification estimator. 3,118 individuals were approached and 683 drivers interviewed, leading to an estimate that 56.3% (SE = 3,5%) of the drivers intended to drive after drinking in less than one hour after the interview. Prevalence was also estimated by sex and broad age groups. The combined use of stratification and inverse sampling enabled a good trade-off between resource and time allocation, while preserving the ability to generalize the findings. The current strategy can be viewed as a step forward in the efforts to improve surveys and estimation for hard-to-reach, mobile populations. PMID:22514620

Spatial Sampling of Weather Data for Regional Crop Yield Simulations

NASA Technical Reports Server (NTRS)

Van Bussel, Lenny G. J.; Ewert, Frank; Zhao, Gang; Hoffmann, Holger; Enders, Andreas; Wallach, Daniel; Asseng, Senthold; Baigorria, Guillermo A.; Basso, Bruno; Biernath, Christian;

Damage localization and quantification of composite stratified beam Structures using residual force method

NASA Astrophysics Data System (ADS)

Behtani, A.; Bouazzouni, A.; Khatir, S.; Tiachacht, S.; Zhou, Y.-L.; Abdel Wahab, M.

2017-05-01

In this paper, the problem of using measured modal parameters to detect and locate damage in beam composite stratified structures with four layers of graphite/epoxy [0°/902°/0°] is investigated. A technique based on the residual force method is applied to composite stratified structure with different boundary conditions, the results of damage detection for several damage cases demonstrate that using residual force method as damage index, the damage location can be identified correctly and the damage extents can be estimated as well.

Multiple sensitive estimation and optimal sample size allocation in the item sum technique.

PubMed

Perri, Pier Francesco; Rueda García, María Del Mar; Cobo Rodríguez, Beatriz

2018-01-01

For surveys of sensitive issues in life sciences, statistical procedures can be used to reduce nonresponse and social desirability response bias. Both of these phenomena provoke nonsampling errors that are difficult to deal with and can seriously flaw the validity of the analyses. The item sum technique (IST) is a very recent indirect questioning method derived from the item count technique that seeks to procure more reliable responses on quantitative items than direct questioning while preserving respondents' anonymity. This article addresses two important questions concerning the IST: (i) its implementation when two or more sensitive variables are investigated and efficient estimates of their unknown population means are required; (ii) the determination of the optimal sample size to achieve minimum variance estimates. These aspects are of great relevance for survey practitioners engaged in sensitive research and, to the best of our knowledge, were not studied so far. In this article, theoretical results for multiple estimation and optimal allocation are obtained under a generic sampling design and then particularized to simple random sampling and stratified sampling designs. Theoretical considerations are integrated with a number of simulation studies based on data from two real surveys and conducted to ascertain the efficiency gain derived from optimal allocation in different situations. One of the surveys concerns cannabis consumption among university students. Our findings highlight some methodological advances that can be obtained in life sciences IST surveys when optimal allocation is achieved. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Training set optimization under population structure in genomic selection.

PubMed

Isidro, Julio; Jannink, Jean-Luc; Akdemir, Deniz; Poland, Jesse; Heslot, Nicolas; Sorrells, Mark E

2015-01-01

Population structure must be evaluated before optimization of the training set population. Maximizing the phenotypic variance captured by the training set is important for optimal performance. The optimization of the training set (TRS) in genomic selection has received much interest in both animal and plant breeding, because it is critical to the accuracy of the prediction models. In this study, five different TRS sampling algorithms, stratified sampling, mean of the coefficient of determination (CDmean), mean of predictor error variance (PEVmean), stratified CDmean (StratCDmean) and random sampling, were evaluated for prediction accuracy in the presence of different levels of population structure. In the presence of population structure, the most phenotypic variation captured by a sampling method in the TRS is desirable. The wheat dataset showed mild population structure, and CDmean and stratified CDmean methods showed the highest accuracies for all the traits except for test weight and heading date. The rice dataset had strong population structure and the approach based on stratified sampling showed the highest accuracies for all traits. In general, CDmean minimized the relationship between genotypes in the TRS, maximizing the relationship between TRS and the test set. This makes it suitable as an optimization criterion for long-term selection. Our results indicated that the best selection criterion used to optimize the TRS seems to depend on the interaction of trait architecture and population structure.

Evaluating effectiveness of down-sampling for stratified designs and unbalanced prevalence in Random Forest models of tree species distributions in Nevada

Treesearch

Elizabeth A. Freeman; Gretchen G. Moisen; Tracy S. Frescino

2012-01-01

Random Forests is frequently used to model species distributions over large geographic areas. Complications arise when data used to train the models have been collected in stratified designs that involve different sampling intensity per stratum. The modeling process is further complicated if some of the target species are relatively rare on the landscape leading to an...

Improving the accuracy of livestock distribution estimates through spatial interpolation.

PubMed

Bryssinckx, Ward; Ducheyne, Els; Muhwezi, Bernard; Godfrey, Sunday; Mintiens, Koen; Leirs, Herwig; Hendrickx, Guy

2012-11-01

Animal distribution maps serve many purposes such as estimating transmission risk of zoonotic pathogens to both animals and humans. The reliability and usability of such maps is highly dependent on the quality of the input data. However, decisions on how to perform livestock surveys are often based on previous work without considering possible consequences. A better understanding of the impact of using different sample designs and processing steps on the accuracy of livestock distribution estimates was acquired through iterative experiments using detailed survey. The importance of sample size, sample design and aggregation is demonstrated and spatial interpolation is presented as a potential way to improve cattle number estimates. As expected, results show that an increasing sample size increased the precision of cattle number estimates but these improvements were mainly seen when the initial sample size was relatively low (e.g. a median relative error decrease of 0.04% per sampled parish for sample sizes below 500 parishes). For higher sample sizes, the added value of further increasing the number of samples declined rapidly (e.g. a median relative error decrease of 0.01% per sampled parish for sample sizes above 500 parishes. When a two-stage stratified sample design was applied to yield more evenly distributed samples, accuracy levels were higher for low sample densities and stabilised at lower sample sizes compared to one-stage stratified sampling. Aggregating the resulting cattle number estimates yielded significantly more accurate results because of averaging under- and over-estimates (e.g. when aggregating cattle number estimates from subcounty to district level, P <0.009 based on a sample of 2,077 parishes using one-stage stratified samples). During aggregation, area-weighted mean values were assigned to higher administrative unit levels. However, when this step is preceded by a spatial interpolation to fill in missing values in non-sampled areas, accuracy is improved remarkably. This counts especially for low sample sizes and spatially even distributed samples (e.g. P <0.001 for a sample of 170 parishes using one-stage stratified sampling and aggregation on district level). Whether the same observations apply on a lower spatial scale should be further investigated.

Bacterial diversity across a highly stratified ecosystem: A salt-wedge Mediterranean estuary.

PubMed

Korlević, M; Šupraha, L; Ljubešić, Z; Henderiks, J; Ciglenečki, I; Dautović, J; Orlić, S

2016-09-01

Highly stratified Mediterranean estuaries are unique environments where the tidal range is low and the tidal currents are almost negligible. The main characteristics of these environments are strong salinity gradients and other environmental parameters. In this study, 454 pyrosequencing of the 16S rRNA gene in combination with catalyzed reporter deposition-fluorescence in situ hybridization (CARD-FISH) was used to estimate the bacterial diversity across the Krka estuary in February and July 2013. The comparison of the data derived from these two techniques resulted in a significant but weak positive correlation (R=0.28) indicating a substantial difference in the bacterial community structure, depending on the applied method. The phytoplankton bloom observed in February was identified as one of the main factors shaping the bacterial community structure between the two environmentally contrasting sampling months. Roseobacter, Bacteroidetes and Gammaproteobacteria differed substantially between February and July. Typical freshwater bacterial classes (Actinobacteria and Betaproteobacteria) showed strong vertical distribution patterns depending on the salinity gradient. Cyanobacteria decreased in abundance in February due to competition with phytoplankton, while the SAR11 clade increased its abundance in July as a result of a better adaptation toward more oligotrophic conditions. The results provided the first detailed insight into the bacterial diversity in a highly stratified Mediterranean karstic estuary. Copyright © 2016 Elsevier GmbH. All rights reserved.

Soil nutrient-landscape relationships in a lowland tropical rainforest in Panama

USGS Publications Warehouse

Barthold, F.K.; Stallard, R.F.; Elsenbeer, H.

2008-01-01

Soils play a crucial role in biogeochemical cycles as spatially distributed sources and sinks of nutrients. Any spatial patterns depend on soil forming processes, our understanding of which is still limited, especially in regards to tropical rainforests. The objective of our study was to investigate the effects of landscape properties, with an emphasis on the geometry of the land surface, on the spatial heterogeneity of soil chemical properties, and to test the suitability of soil-landscape modeling as an appropriate technique to predict the spatial variability of exchangeable K and Mg in a humid tropical forest in Panama. We used a design-based, stratified sampling scheme to collect soil samples at 108 sites on Barro Colorado Island, Panama. Stratifying variables are lithology, vegetation and topography. Topographic variables were generated from high-resolution digital elevation models with a grid size of 5 m. We took samples from five depths down to 1 m, and analyzed for total and exchangeable K and Mg. We used simple explorative data analysis techniques to elucidate the importance of lithology for soil total and exchangeable K and Mg. Classification and Regression Trees (CART) were adopted to investigate importance of topography, lithology and vegetation for the spatial distribution of exchangeable K and Mg and with the intention to develop models that regionalize the point observations using digital terrain data as explanatory variables. Our results suggest that topography and vegetation do not control the spatial distribution of the selected soil chemical properties at a landscape scale and lithology is important to some degree. Exchangeable K is distributed equally across the study area indicating that other than landscape processes, e.g. biogeochemical processes, are responsible for its spatial distribution. Lithology contributes to the spatial variation of exchangeable Mg but controlling variables could not be detected. The spatial variation of soil total K and Mg is mainly influenced by lithology. ?? 2007 Elsevier B.V. All rights reserved.

Inventory of forest resources (including water) by multi-level sampling. [nine northern Virginia coastal plain counties

NASA Technical Reports Server (NTRS)

Aldrich, R. C.; Dana, R. W.; Roberts, E. H. (Principal Investigator)

1977-01-01

The author has identified the following significant results. A stratified random sample using LANDSAT band 5 and 7 panchromatic prints resulted in estimates of water in counties with sampling errors less than + or - 9% (67% probability level). A forest inventory using a four band LANDSAT color composite resulted in estimates of forest area by counties that were within + or - 6.7% and + or - 3.7% respectively (67% probability level). Estimates of forest area for counties by computer assisted techniques were within + or - 21% of operational forest survey figures and for all counties the difference was only one percent. Correlations of airborne terrain reflectance measurements with LANDSAT radiance verified a linear atmospheric model with an additive (path radiance) term and multiplicative (transmittance) term. Coefficients of determination for 28 of the 32 modeling attempts, not adverseley affected by rain shower occurring between the times of LANDSAT passage and aircraft overflights, exceeded 0.83.

Framing Child Sexual Abuse: A Longitudinal Content Analysis of Newspaper and Television Coverage, 2002-2012.

PubMed

Weatherred, Jane Long

2017-01-01

The way in which the news media frame child sexual abuse can influence public perception. This content analysis of the child sexual abuse coverage of eight national news organizations in the United States from 2002 to 2012 includes the two dominant events of the Catholic Church and Pennsylvania State University child sexual abuse scandals. Census and systematic stratified sampling techniques were applied to articles obtained from the Lexis/Nexis Academic database, resulting in a sample of 503 articles. Intercoder reliability was ensured by double coding a randomly selected sample. Study findings indicate a shift in the attribution of responsibility of child sexual abuse among news organizations over the past decade from an individual-level problem with individual-level solutions to a societal-level problem with institutional culpability. Nevertheless, individual-level solutions continue to be framed as the best possible solution.

Language with Character: A Stratified Corpus Comparison of Individual Differences in E-Mail Communication

ERIC Educational Resources Information Center

Oberlander, Jon; Gill, Alastair J.

2006-01-01

To what extent does the wording and syntactic form of people's writing reflect their personalities? Using a bottom-up stratified corpus comparison, rather than the top-down content analysis techniques that have been used before, we examine a corpus of e-mail messages elicited from individuals of known personality, as measured by the Eysenck…

[Study of spatial stratified sampling strategy of Oncomelania hupensis snail survey based on plant abundance].

PubMed

Xun-Ping, W; An, Z

2017-07-27

Objective To optimize and simplify the survey method of Oncomelania hupensis snails in marshland endemic regions of schistosomiasis, so as to improve the precision, efficiency and economy of the snail survey. Methods A snail sampling strategy (Spatial Sampling Scenario of Oncomelania based on Plant Abundance, SOPA) which took the plant abundance as auxiliary variable was explored and an experimental study in a 50 m×50 m plot in a marshland in the Poyang Lake region was performed. Firstly, the push broom surveyed data was stratified into 5 layers by the plant abundance data; then, the required numbers of optimal sampling points of each layer through Hammond McCullagh equation were calculated; thirdly, every sample point in the line with the Multiple Directional Interpolation (MDI) placement scheme was pinpointed; and finally, the comparison study among the outcomes of the spatial random sampling strategy, the traditional systematic sampling method, the spatial stratified sampling method, Sandwich spatial sampling and inference and SOPA was performed. Results The method (SOPA) proposed in this study had the minimal absolute error of 0.213 8; and the traditional systematic sampling method had the largest estimate, and the absolute error was 0.924 4. Conclusion The snail sampling strategy (SOPA) proposed in this study obtains the higher estimation accuracy than the other four methods.

Evaluating cost-efficiency and accuracy of hunter harvest survey designs

USGS Publications Warehouse

Lukacs, P.M.; Gude, J.A.; Russell, R.E.; Ackerman, B.B.

2011-01-01

Effective management of harvested wildlife often requires accurate estimates of the number of animals harvested annually by hunters. A variety of techniques exist to obtain harvest data, such as hunter surveys, check stations, mandatory reporting requirements, and voluntary reporting of harvest. Agencies responsible for managing harvested wildlife such as deer (Odocoileus spp.), elk (Cervus elaphus), and pronghorn (Antilocapra americana) are challenged with balancing the cost of data collection versus the value of the information obtained. We compared precision, bias, and relative cost of several common strategies, including hunter self-reporting and random sampling, for estimating hunter harvest using a realistic set of simulations. Self-reporting with a follow-up survey of hunters who did not report produces the best estimate of harvest in terms of precision and bias, but it is also, by far, the most expensive technique. Self-reporting with no followup survey risks very large bias in harvest estimates, and the cost increases with increased response rate. Probability-based sampling provides a substantial cost savings, though accuracy can be affected by nonresponse bias. We recommend stratified random sampling with a calibration estimator used to reweight the sample based on the proportions of hunters responding in each covariate category as the best option for balancing cost and accuracy. ?? 2011 The Wildlife Society.

Advances in the Assessment of Wind Turbine Operating Extreme Loads via More Efficient Calculation Approaches

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

Graf, Peter; Damiani, Rick R.; Dykes, Katherine

2017-01-09

A new adaptive stratified importance sampling (ASIS) method is proposed as an alternative approach for the calculation of the 50 year extreme load under operational conditions, as in design load case 1.1 of the the International Electrotechnical Commission design standard. ASIS combines elements of the binning and extrapolation technique, currently described by the standard, and of the importance sampling (IS) method to estimate load probability of exceedances (POEs). Whereas a Monte Carlo (MC) approach would lead to the sought level of POE with a daunting number of simulations, IS-based techniques are promising as they target the sampling of the inputmore » parameters on the parts of the distributions that are most responsible for the extreme loads, thus reducing the number of runs required. We compared the various methods on select load channels as output from FAST, an aero-hydro-servo-elastic tool for the design and analysis of wind turbines developed by the National Renewable Energy Laboratory (NREL). Our newly devised method, although still in its infancy in terms of tuning of the subparameters, is comparable to the others in terms of load estimation and its variance versus computational cost, and offers great promise going forward due to the incorporation of adaptivity into the already powerful importance sampling concept.« less

CROP type analysis using Landsat digital data

NASA Technical Reports Server (NTRS)

Brown, C. E.; Thomas, R. W.; Wall, S. L.

1981-01-01

Classification and statistical sampling techniques for crop type discrimination using Landsat digital data have been developed by the University of California in cooperation with NASA and the California Department of Water Resources. Ratioed bands (MSS 7/5 and 5/4) and a sun-angle corrected Euclidean albedo band were prepared from data for the Sacramento Valley for five different dates. The test area was stratified into general crop groupings based on the particular patterns of irrigation timing for each crop. Data classified within each stratum were used to produce a crop type map. Comparison with ground data indicates that certain crops and crop groups are discernable. Small grains and rice are easily identifiable, as are deciduous fruit varieties as a group. However, it is not feasible to separate various fruit and nut varieties, or separate vegetable crops with these techniques at present.

DSM-5 field trials in the United States and Canada, Part I: study design, sampling strategy, implementation, and analytic approaches.

PubMed

Clarke, Diana E; Narrow, William E; Regier, Darrel A; Kuramoto, S Janet; Kupfer, David J; Kuhl, Emily A; Greiner, Lisa; Kraemer, Helena C

2013-01-01

This article discusses the design,sampling strategy, implementation,and data analytic processes of the DSM-5 Field Trials. The DSM-5 Field Trials were conducted by using a test-retest reliability design with a stratified sampling approach across six adult and four pediatric sites in the United States and one adult site in Canada. A stratified random sampling approach was used to enhance precision in the estimation of the reliability coefficients. A web-based research electronic data capture system was used for simultaneous data collection from patients and clinicians across sites and for centralized data management.Weighted descriptive analyses, intraclass kappa and intraclass correlation coefficients for stratified samples, and receiver operating curves were computed. The DSM-5 Field Trials capitalized on advances since DSM-III and DSM-IV in statistical measures of reliability (i.e., intraclass kappa for stratified samples) and other recently developed measures to determine confidence intervals around kappa estimates. Diagnostic interviews using DSM-5 criteria were conducted by 279 clinicians of varied disciplines who received training comparable to what would be available to any clinician after publication of DSM-5.Overall, 2,246 patients with various diagnoses and levels of comorbidity were enrolled,of which over 86% were seen for two diagnostic interviews. A range of reliability coefficients were observed for the categorical diagnoses and dimensional measures. Multisite field trials and training comparable to what would be available to any clinician after publication of DSM-5 provided “real-world” testing of DSM-5 proposed diagnoses.

Using known map category marginal frequencies to improve estimates of thematic map accuracy

NASA Technical Reports Server (NTRS)

Card, D. H.

1982-01-01

By means of two simple sampling plans suggested in the accuracy-assessment literature, it is shown how one can use knowledge of map-category relative sizes to improve estimates of various probabilities. The fact that maximum likelihood estimates of cell probabilities for the simple random sampling and map category-stratified sampling were identical has permitted a unified treatment of the contingency-table analysis. A rigorous analysis of the effect of sampling independently within map categories is made possible by results for the stratified case. It is noted that such matters as optimal sample size selection for the achievement of a desired level of precision in various estimators are irrelevant, since the estimators derived are valid irrespective of how sample sizes are chosen.

Stratified estimation of forest area using satellite imagery, inventory data, and the k-nearest neighbors technique

Treesearch

Ronald E. McRoberts; Mark D. Nelson; Daniel G. Wendt

2002-01-01

For two large study areas in Minnesota, USA, stratified estimation using classified Landsat Thematic Mapper satellite imagery as the basis for stratification was used to estimate forest area. Measurements of forest inventory plots obtained for a 12-month period in 1998 and 1999 were used as the source of data for within-stratum estimates. These measurements further...

Validating the Goldstein-Wehner Law for the Stratified Positive Column of DC Discharge in an Undergraduate Laboratory

ERIC Educational Resources Information Center

Lisovskiy, V. A.; Koval, V. A.; Artushenko, E. P.; Yegorenkov, V. D.

2012-01-01

In this paper we suggest a simple technique for validating the Goldstein-Wehner law for a stratified positive column of dc glow discharge while studying the properties of gas discharges in an undergraduate laboratory. To accomplish this a simple device with a pre-vacuum mechanical pump, dc source and gas pressure gauge is required. Experiments may…

Stratified estimates of forest area using the k-nearest neighbors technique and satellite imagery

Treesearch

Ronald E. McRoberts; Mark D. Nelson; Daniel Wendt

2002-01-01

For two study areas in Minnesota, stratified estimation using Landsat Thematic Mapper satellite imagery as the basis for stratification was used to estimate forest area. Measurements of forest inventory plots obtained for a 12-month period in 1998 and 1999 were used as the source of data for within-strata estimates. These measurements further served as calibration data...

Design and simulation of stratified probability digital receiver with application to the multipath communication

NASA Technical Reports Server (NTRS)

Deal, J. H.

1975-01-01

One approach to the problem of simplifying complex nonlinear filtering algorithms is through using stratified probability approximations where the continuous probability density functions of certain random variables are represented by discrete mass approximations. This technique is developed in this paper and used to simplify the filtering algorithms developed for the optimum receiver for signals corrupted by both additive and multiplicative noise.

An evaluation of space acquired data as a tool for management to wildlife habitat in Alaska

NASA Technical Reports Server (NTRS)

Vantries, B. J.

1973-01-01

The Bureau of Sport Fisheries and Wildlife ERTS experiment in Alaska attempts to yield information useful for three primary functions in the State. They are: (1) to test the feasibility of using ERTS data, in conjunction with aircraft acquired multispectral photography, to develop effective stratified sampling techniques, (2) to provide near real time assessment and evaluation of the quantity, quality, and distribution of waterfowl breeding habitat through frequent ERTS measurements of hydrologic, phenological and vegetational parameters, and (3) to provide basic mapping of vegetation and terrain in certain remote areas of the State for which little or no biological data now exist.

Employee resourcing strategies and universities' corporate image: A survey dataset.

PubMed

Falola, Hezekiah Olubusayo; Oludayo, Olumuyiwa Akinrole; Olokundun, Maxwell Ayodele; Salau, Odunayo Paul; Ibidunni, Ayodotun Stephen; Igbinoba, Ebe

2018-06-01

The data examined the effect of employee resourcing strategies on corporate image. The data were generated from a total of 500 copies of questionnaire administered to the academic staff of the six (6) selected private Universities in Southwest, Nigeria, out of which four hundred and forty-three (443) were retrieved. Stratified and simple random sampling techniques were used to select the respondents for this study. Descriptive and Linear Regression, were used for the presentation of the data. Mean score was used as statistical tool of analysis. Therefore, the data presented in this article is made available to facilitate further and more comprehensive investigation on the subject matter.

Exploring Oral Health Beliefs and Behaviour Among Tibetan Immigrants of Bylakkupe.

PubMed

Sivakumar, Vivek; Jain, Jithesh; Battur, Hemanth; Patil, Pavan Uday; Lingaraj, Sunil; Palliyal, Shanavaz

2016-01-01

To explore the oral health beliefs and behaviour among Tibetan immigrants of Bylakkupe village. A stratified random sampling technique involving 366 Tibetan monks in Bylakkupe monasteries was used in this study. The oral health beliefs were measured using a pre-tested questionnaire. The results showed that seriousness was higher compared to other domains in the health belief model. Further, as the duration of the stay increased, the perceived importance was also higher among the population studied. The results show that in general, although the seriousness of oral health was high among the participants, the perceived benefit of dental treatment was relatively low.

Robust computation of dipole electromagnetic fields in arbitrarily anisotropic, planar-stratified environments.

PubMed

Sainath, Kamalesh; Teixeira, Fernando L; Donderici, Burkay

2014-01-01

We develop a general-purpose formulation, based on two-dimensional spectral integrals, for computing electromagnetic fields produced by arbitrarily oriented dipoles in planar-stratified environments, where each layer may exhibit arbitrary and independent anisotropy in both its (complex) permittivity and permeability tensors. Among the salient features of our formulation are (i) computation of eigenmodes (characteristic plane waves) supported in arbitrarily anisotropic media in a numerically robust fashion, (ii) implementation of an hp-adaptive refinement for the numerical integration to evaluate the radiation and weakly evanescent spectra contributions, and (iii) development of an adaptive extension of an integral convergence acceleration technique to compute the strongly evanescent spectrum contribution. While other semianalytic techniques exist to solve this problem, none have full applicability to media exhibiting arbitrary double anisotropies in each layer, where one must account for the whole range of possible phenomena (e.g., mode coupling at interfaces and nonreciprocal mode propagation). Brute-force numerical methods can tackle this problem but only at a much higher computational cost. The present formulation provides an efficient and robust technique for field computation in arbitrary planar-stratified environments. We demonstrate the formulation for a number of problems related to geophysical exploration.

Validation of a multilevel sampling device to determine the vertical variability of chlorinated solvent in a contaminated aquifer.

PubMed

Barnier, C; Palmier, C; Atteia, O

2013-01-01

The vertical heterogeneity of contaminant concentrations in aquifers is well known, but obtaining representative samples is still a subject of debate. In this paper, the question arises from sites where numerous fully screened wells exist and there is a need to define the vertical distribution of contaminants. For this purpose, several wells were investigated with different techniques on a site contaminated with chlorinated solvents. A core-bored well shows that a tetrachloroethene (PCE) phase is sitting on and infiltrating a less permeable layer. Downstream of the cored well, the following sampling techniques were compared on fully screened wells: low flow pumping at several depths, pumping between packers and a new multilevel sampler for fully screened wells. Concerning low flow rate pumping, very low gradients were found, which may be due to the existence of vertical flow inside the well or in the gravel pack. Sampling between packers gave results comparable with the cores, separating a layer with PCE and trichloroethene from another one with cis 1,2-dichloroethene and vinyl chloride as major compounds. Detailed sampling according to pumped volume shows that even between packers, cleaning of the inter-packer volume is necessary before each sampling. Lastly, the proposed new multilevel sampler gives results similar to the packers but has the advantages of much faster sampling and a constant vertical positioning, which is fairly important for long-term monitoring in highly stratified aquifers.

Accuracy assessment, using stratified plurality sampling, of portions of a LANDSAT classification of the Arctic National Wildlife Refuge Coastal Plain

NASA Technical Reports Server (NTRS)

Card, Don H.; Strong, Laurence L.

1989-01-01

An application of a classification accuracy assessment procedure is described for a vegetation and land cover map prepared by digital image processing of LANDSAT multispectral scanner data. A statistical sampling procedure called Stratified Plurality Sampling was used to assess the accuracy of portions of a map of the Arctic National Wildlife Refuge coastal plain. Results are tabulated as percent correct classification overall as well as per category with associated confidence intervals. Although values of percent correct were disappointingly low for most categories, the study was useful in highlighting sources of classification error and demonstrating shortcomings of the plurality sampling method.

Statistical issues in reporting quality data: small samples and casemix variation.

PubMed

Zaslavsky, A M

2001-12-01

To present two key statistical issues that arise in analysis and reporting of quality data. Casemix variation is relevant to quality reporting when the units being measured have differing distributions of patient characteristics that also affect the quality outcome. When this is the case, adjustment using stratification or regression may be appropriate. Such adjustments may be controversial when the patient characteristic does not have an obvious relationship to the outcome. Stratified reporting poses problems for sample size and reporting format, but may be useful when casemix effects vary across units. Although there are no absolute standards of reliability, high reliabilities (interunit F > or = 10 or reliability > or = 0.9) are desirable for distinguishing above- and below-average units. When small or unequal sample sizes complicate reporting, precision may be improved using indirect estimation techniques that incorporate auxiliary information, and 'shrinkage' estimation can help to summarize the strength of evidence about units with small samples. With broader understanding of casemix adjustment and methods for analyzing small samples, quality data can be analysed and reported more accurately.

Data splitting for artificial neural networks using SOM-based stratified sampling.

PubMed

May, R J; Maier, H R; Dandy, G C

2010-03-01

Data splitting is an important consideration during artificial neural network (ANN) development where hold-out cross-validation is commonly employed to ensure generalization. Even for a moderate sample size, the sampling methodology used for data splitting can have a significant effect on the quality of the subsets used for training, testing and validating an ANN. Poor data splitting can result in inaccurate and highly variable model performance; however, the choice of sampling methodology is rarely given due consideration by ANN modellers. Increased confidence in the sampling is of paramount importance, since the hold-out sampling is generally performed only once during ANN development. This paper considers the variability in the quality of subsets that are obtained using different data splitting approaches. A novel approach to stratified sampling, based on Neyman sampling of the self-organizing map (SOM), is developed, with several guidelines identified for setting the SOM size and sample allocation in order to minimize the bias and variance in the datasets. Using an example ANN function approximation task, the SOM-based approach is evaluated in comparison to random sampling, DUPLEX, systematic stratified sampling, and trial-and-error sampling to minimize the statistical differences between data sets. Of these approaches, DUPLEX is found to provide benchmark performance with good model performance, with no variability. The results show that the SOM-based approach also reliably generates high-quality samples and can therefore be used with greater confidence than other approaches, especially in the case of non-uniform datasets, with the benefit of scalability to perform data splitting on large datasets. Copyright 2009 Elsevier Ltd. All rights reserved.

Nonmedical influences on medical decision making: an experimental technique using videotapes, factorial design, and survey sampling.

PubMed Central

Feldman, H A; McKinlay, J B; Potter, D A; Freund, K M; Burns, R B; Moskowitz, M A; Kasten, L E

1997-01-01

OBJECTIVE: To study nonmedical influences on the doctor-patient interaction. A technique using simulated patients and "real" doctors is described. DATA SOURCES: A random sample of physicians, stratified on such characteristics as demographics, specialty, or experience, and selected from commercial and professional listings. STUDY DESIGN: A medical appointment is depicted on videotape by professional actors. The patient's presenting complaint (e.g., chest pain) allows a range of valid interpretation. Several alternative versions are taped, featuring the same script with patient-actors of different age, sex, race, or other characteristics. Fractional factorial design is used to select a balanced subset of patient characteristics, reducing costs without biasing the outcome. DATA COLLECTION: Each physician is shown one version of the videotape appointment and is asked to describe how he or she would diagnose or treat such a patient. PRINCIPAL FINDINGS: Two studies using this technique have been completed to date, one involving chest pain and dyspnea and the other involving breast cancer. The factorial design provided sufficient power, despite limited sample size, to demonstrate with statistical significance various influences of the experimental and stratification variables, including the patient's gender and age and the physician's experience. Persistent recruitment produced a high response rate, minimizing selection bias and enhancing validity. CONCLUSION: These techniques permit us to determine, with a degree of control unattainable in observational studies, whether medical decisions as described by actual physicians and drawn from a demographic or professional group of interest, are influenced by a prescribed set of nonmedical factors. PMID:9240285

Language Learning Motivation in China: Results of a Large-Scale Stratified Survey

ERIC Educational Resources Information Center

You, Chenjing; Dörnyei, Zoltán

2016-01-01

This article reports on the findings of a large-scale cross-sectional survey of the motivational disposition of English language learners in secondary schools and universities in China. The total sample involved over 10,000 students and was stratified according to geographical region and teaching contexts, selecting participants both from urban…

Statistical design and analysis of environmental studies for plutonium and other transuranics at NAEG ''safety-shot'' sites

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

Gilbert, R.O.; Eberhardt, L.L.; Fowler, E.B.

This paper is centered around the use of stratified random sampling for estimating the total amount (inventory) of $sup 239-240$Pu and uranium in surface soil at ten ''safety-shot'' sites on the Nevada Test Site (NTS) and Tonopah Test Range (TTR) that are currently being studied by the Nevada Applied Ecology Group (NAEG). The use of stratified random sampling has resulted in estimates of inventory at these desert study sites that have smaller standard errors than would have been the case had simple random sampling (no stratification) been used. Estimates of inventory are given for $sup 235$U, $sup 238$U, and $supmore » 239-240$Pu in soil at A Site of Area 11 on the NTS. Other results presented include average concentrations of one or more of these isotopes in soil and vegetation and in soil profile samples at depths to 25 cm. The regression relationship between soil and vegetation concentrations of $sup 235$U and $sup 238$U at adjacent sampling locations is also examined using three different models. The applicability of stratified random sampling to the estimation of concentration contours of $sup 239-240$Pu in surface soil using computer algorithms is also investigated. Estimates of such contours are obtained using several different methods. The planning of field sampling plans for estimating inventory and distribution is discussed. (auth)« less

Correcting Classifiers for Sample Selection Bias in Two-Phase Case-Control Studies

PubMed Central

Theis, Fabian J.

2017-01-01

Epidemiological studies often utilize stratified data in which rare outcomes or exposures are artificially enriched. This design can increase precision in association tests but distorts predictions when applying classifiers on nonstratified data. Several methods correct for this so-called sample selection bias, but their performance remains unclear especially for machine learning classifiers. With an emphasis on two-phase case-control studies, we aim to assess which corrections to perform in which setting and to obtain methods suitable for machine learning techniques, especially the random forest. We propose two new resampling-based methods to resemble the original data and covariance structure: stochastic inverse-probability oversampling and parametric inverse-probability bagging. We compare all techniques for the random forest and other classifiers, both theoretically and on simulated and real data. Empirical results show that the random forest profits from only the parametric inverse-probability bagging proposed by us. For other classifiers, correction is mostly advantageous, and methods perform uniformly. We discuss consequences of inappropriate distribution assumptions and reason for different behaviors between the random forest and other classifiers. In conclusion, we provide guidance for choosing correction methods when training classifiers on biased samples. For random forests, our method outperforms state-of-the-art procedures if distribution assumptions are roughly fulfilled. We provide our implementation in the R package sambia. PMID:29312464

SNP selection and classification of genome-wide SNP data using stratified sampling random forests.

PubMed

Wu, Qingyao; Ye, Yunming; Liu, Yang; Ng, Michael K

2012-09-01

For high dimensional genome-wide association (GWA) case-control data of complex disease, there are usually a large portion of single-nucleotide polymorphisms (SNPs) that are irrelevant with the disease. A simple random sampling method in random forest using default mtry parameter to choose feature subspace, will select too many subspaces without informative SNPs. Exhaustive searching an optimal mtry is often required in order to include useful and relevant SNPs and get rid of vast of non-informative SNPs. However, it is too time-consuming and not favorable in GWA for high-dimensional data. The main aim of this paper is to propose a stratified sampling method for feature subspace selection to generate decision trees in a random forest for GWA high-dimensional data. Our idea is to design an equal-width discretization scheme for informativeness to divide SNPs into multiple groups. In feature subspace selection, we randomly select the same number of SNPs from each group and combine them to form a subspace to generate a decision tree. The advantage of this stratified sampling procedure can make sure each subspace contains enough useful SNPs, but can avoid a very high computational cost of exhaustive search of an optimal mtry, and maintain the randomness of a random forest. We employ two genome-wide SNP data sets (Parkinson case-control data comprised of 408 803 SNPs and Alzheimer case-control data comprised of 380 157 SNPs) to demonstrate that the proposed stratified sampling method is effective, and it can generate better random forest with higher accuracy and lower error bound than those by Breiman's random forest generation method. For Parkinson data, we also show some interesting genes identified by the method, which may be associated with neurological disorders for further biological investigations.

The Association Between Body Mass Index and Open-angle Glaucoma in a South Korean Population-based Sample.

PubMed

Lin, Shuai-Chun; Pasquale, Louis R; Singh, Kuldev; Lin, Shan C

2018-03-01

The purpose of this article is to investigate the association between body mass index (BMI) and open-angle glaucoma (OAG) in a sample of the South Korean population. The sample consisted of a cross-sectional, population-based sample of 10,978 participants, 40 years of age and older, enrolled in the 2008 to 2011 Korean National Health and Nutrition Examination Survey. All participants had measured intraocular pressure <22 mm Hg and open anterior chamber angles. OAG was defined using disc and visual field criteria established by the International Society for Geographical and Epidemiological Ophthalmology. Multivariable analyses were performed to determine the association between BMI and OAG. These analyses were also performed in a sex-stratified and age-stratified manner. After adjusting for potential confounding variables, lower BMI (<19 kg/m) was associated with greater risk of OAG compared with normal BMI (19 to 24.9 kg/m) [odds ratio (OR), 2.28; 95% confidence interval (CI), 1.22-4.26]. In sex-stratified analyses, low BMI remained adversely related to glaucoma in women (OR, 3.45; 95% CI, 1.42-8.38) but not in men (OR, 1.72; 95% CI, 0.71-4.20). In age-stratified analyses, lower BMI was adversely related to glaucoma among subjects 40- to 49-year old (OR, 5.16; 95% CI, 1.86-14.36) but differences in glaucoma prevalence were not statistically significant between those with low versus normal BMI in other age strata. Lower BMI was associated with increased odds of OAG in a sample of the South Korean population. Multivariate analysis revealed the association to be statistically significant in women and those in the youngest age stratum.

Psychological Determinants of Emotional Eating in Adolescence

PubMed Central

NGUYEN-RODRIGUEZ, SELENA T.; UNGER, JENNIFER B.; SPRUIJT-METZ, DONNA

2010-01-01

Emotional eating is conceptualized as eating in response to negative affect. Data from a larger study of physical activity was employed to examine the associations among specific emotions/moods and emotional eating in an adolescent sample. Six-hundred and sixty-six students of diverse backgrounds from 7 middle schools in Los Angeles County participated. Cross-sectional analysis revealed no gender differences in emotional eating, and showed that perceived stress and worries were associated with emotional eating in the total sample. Gender stratified analyses revealed significant associations of perceived stress, worries and tension/anxiety to emotional eating for girls, while only confused mood was related to emotional eating in boys. These findings bear potential implications for the treatment and prevention of pediatric obesity and eating disorders because they suggest that interventions would benefit from incorporation of stress-reduction techniques and promotion of positive mood. PMID:19391020

Stratification of American hearing aid users by age and audiometric characteristics: a method for representative sampling.

PubMed

Aronoff, Justin M; Yoon, Yang-soo; Soli, Sigfrid D

2010-06-01

Stratified sampling plans can increase the accuracy and facilitate the interpretation of a dataset characterizing a large population. However, such sampling plans have found minimal use in hearing aid (HA) research, in part because of a paucity of quantitative data on the characteristics of HA users. The goal of this study was to devise a quantitatively derived stratified sampling plan for HA research, so that such studies will be more representative and generalizable, and the results obtained using this method are more easily reinterpreted as the population changes. Pure-tone average (PTA) and age information were collected for 84,200 HAs acquired in 2006 and 2007. The distribution of PTA and age was quantified for each HA type and for a composite of all HA users. Based on their respective distributions, PTA and age were each divided into three groups, the combination of which defined the stratification plan. The most populous PTA and age group was also subdivided, allowing greater homogeneity within strata. Finally, the percentage of users in each stratum was calculated. This article provides a stratified sampling plan for HA research, based on a quantitative analysis of the distribution of PTA and age for HA users. Adopting such a sampling plan will make HA research results more representative and generalizable. In addition, data acquired using such plans can be reinterpreted as the HA population changes.

Geohydrology and water quality of stratified-drift aquifers in the middle Merrimack River basin, south-central New Hampshire

USGS Publications Warehouse

Ayotte, Joseph D.; Toppin, Kenneth W.

1995-01-01

The U.S. Geological Survey, in cooperation with the State of New Hampshire, Department of Environmental Services, Water Resources Division has assessed the geohydrology and water quality of stratified-drift aquifers in the middle Merrimack River basin in south-central New Hampshire. The middle Merrimack River basin drains 469 square miles; 98 square miles is underlain by stratified-drift aquifers. Saturated thickness of stratified drift within the study area is generally less than 40 feet but locally greater than 100 feet. Transmissivity of stratified-drift aquifers is generally less than 2,000 feet squared per day but locally exceeds 6, 000 feet squared per day. At present (1990), ground-water withdrawals from stratified drift for public supply are about 0.4 million gallons per day within the basin. Many of the stratified-drift aquifers within the study area are not developed to their fullest potential. The geohydrology of stratified-drift aquifers was investigated by focusing on basic aquifer properties, including aquifer boundaries; recharge, discharge, and direction of ground-water flow; saturated thickness and storage; and transmissivity. Surficial geologic mapping assisted in the determination of aquifer boundaries. Data from 757 wells and test borings were used to produce maps of water-table altitude, saturated thickness, and transmissivity of stratified drift. More than 10 miles of seismic-refraction profiling and 14 miles of seismic-reflection profiling were also used to construct the water table and saturated-thickness maps. Stratified-drift aquifers in the southern, western, and central parts of the study area are typically small and discontinuous, whereas aquifers in the eastern part along the Merrimack River valley are continuous. The Merrimack River valley aquifers formed in glacial Lakes Merrimack and Hooksett. Many other smaller discontinuous aquifers formed in small temporary ponds during deglaciation. A stratified-drift aquifer in Goffstown was analyzed for aquifer yield by use of a two-dimensional, finite-difference ground-water-flow model. Yield of the Goffstown aquifer was estimated to be 2.5 million gallons per day. Sensitivity analysis showed that the estimate of aquifer yield was most sensitive to changes in hydraulic conductivity. The amount of water induced into the aquifer from the Piscataquog River was most affected by changes in estimates of streambed conductance. Results of analysis of water samples from 10 test wells indicate that, with some exceptions, water in the stratified-drift aquifers generally meets U.S. Environmental Protection Agency primary and secondary drinking-water regulations. Water from two wells had elevated sodium concentrations, waterfront two wells had elevated concentrations of dissolved iron, and waterfront seven wells had elevated concentrations of manganese. Known areas of contamination were avoided during water-quality sampling.

First detection of mycobacteria in African rodents and insectivores, using stratified pool screening.

PubMed

Durnez, Lies; Eddyani, Miriam; Mgode, Georgies F; Katakweba, Abdul; Katholi, Charles R; Machang'u, Robert R; Kazwala, Rudovik R; Portaels, Françoise; Leirs, Herwig

2008-02-01

With the rising number of patients with human immunodeficiency virus (HIV)/AIDS in developing countries, the control of mycobacteria is of growing importance. Previous studies have shown that rodents and insectivores are carriers of mycobacteria. However, it is not clear how widespread mycobacteria are in these animals and what their role is in spreading them. Therefore, the prevalence of mycobacteria in rodents and insectivores was studied in and around Morogoro, Tanzania. Live rodents were trapped, with three types of live traps, in three habitats. Pieces of organs were pooled per habitat, species, and organ type (stratified pooling); these sample pools were examined for the presence of mycobacteria by PCR, microscopy, and culture methods. The mycobacterial isolates were identified using phenotypic techniques and sequencing. In total, 708 small mammals were collected, 31 of which were shrews. By pool prevalence estimation, 2.65% of the animals were carriers of mycobacteria, with a higher prevalence in the urban areas and in Cricetomys gambianus and the insectivore Crocidura hirta. Nontuberculous mycobacteria (Mycobacterium chimaera, M. intracellulare, M. arupense, M. parascrofulaceum, and Mycobacterium spp.) were isolated from C. gambianus, Mastomys natalensis, and C. hirta. This study is the first to report findings of mycobacteria in African rodents and insectivores and the first in mycobacterial ecology to estimate the prevalence of mycobacteria after stratified pool screening. The fact that small mammals in urban areas carry more mycobacteria than those in the fields and that potentially pathogenic mycobacteria were isolated identifies a risk for other animals and humans, especially HIV/AIDS patients, that have a weakened immune system.

Seasonal change of phytoplankton (spring vs. summer) in the southern Patagonian shelf

NASA Astrophysics Data System (ADS)

Gonçalves-Araujo, Rafael; de Souza, Márcio Silva; Mendes, Carlos Rafael Borges; Tavano, Virginia Maria; Garcia, Carlos A. E.

2016-08-01

As part of the Patagonian Experiment (PATEX) project two sequential seasons (spring/summer 2007-2008) were sampled in the southern Patagonian shelf, when physical-chemical-biological (phytoplankton) data were collected. Phytoplankton biomass and community composition were assessed through both microscopic and high-performance liquid chromatography/chemical taxonomy (HPLC/CHEMTAX) techniques and related to both in situ and satellite data at spatial and seasonal scales. Phytoplankton seasonal variation was clearly modulated by water column thermohaline structure and nutrient dynamics [mainly dissolved inorganic nitrogen (DIN) and silicate]. The spring phytoplankton community showed elevated biomass and was dominated by diatoms [mainly Corethron pennatum and small (<20 μm) cells of Thalassiosira spp.], associated with a deeper and more weakly stratified upper mixed layer depth (UMLD) and relatively low nutrient concentrations, which were probably a result of consumption by the diatom bloom. In contrast, the phytoplankton community in summer presented lower biomass and was mainly dominated by haptophytes (primarily Emiliania huxleyi and Phaeocystis antarctica) and dinoflagellates, associated with shallower and well-stratified upper mixed layers with higher nutrient concentrations, likely due to lateral advection of nutrient-rich waters from the Malvinas Current. The gradual establishment of a strongly stratified and shallow UMLD as season progressed, was an important factor leading to the replacement of the spring diatom community by a dominance of calcifying organisms, as shown in remote sensing imagery and confirmed by microscopic examination. Furthermore, in spring, phaeopigments a (degradation products of chlorophyll a) relative to chlorophyll a, were twice that of summer, indicating the diatom bloom was under higher grazing pressure.

Sampling error in timber surveys

Treesearch

Austin Hasel

1938-01-01

Various sampling strategies are evaluated for efficiency in an interior ponderosa pine forest. In a 5760 acre tract, efficiency was gained by stratifying into quarter acre blocks and sampling randomly from within. A systematic cruise was found to be superior for volume estimation.

Development of a sampling strategy and sample size calculation to estimate the distribution of mammographic breast density in Korean women.

PubMed

Jun, Jae Kwan; Kim, Mi Jin; Choi, Kui Son; Suh, Mina; Jung, Kyu-Won

2012-01-01

Mammographic breast density is a known risk factor for breast cancer. To conduct a survey to estimate the distribution of mammographic breast density in Korean women, appropriate sampling strategies for representative and efficient sampling design were evaluated through simulation. Using the target population from the National Cancer Screening Programme (NCSP) for breast cancer in 2009, we verified the distribution estimate by repeating the simulation 1,000 times using stratified random sampling to investigate the distribution of breast density of 1,340,362 women. According to the simulation results, using a sampling design stratifying the nation into three groups (metropolitan, urban, and rural), with a total sample size of 4,000, we estimated the distribution of breast density in Korean women at a level of 0.01% tolerance. Based on the results of our study, a nationwide survey for estimating the distribution of mammographic breast density among Korean women can be conducted efficiently.

Numerical modeling of subsurface communication

NASA Astrophysics Data System (ADS)

Burke, G. J.; Dease, C. G.; Didwall, E. M.; Lytle, R. J.

1985-02-01

Techniques are described for numerical modeling of through-the-Earth communication. The basic problem considered is evaluation of the field at a surface or airborne station due to an antenna buried in the Earth. Equations are given for the field of a point source in a homogeneous or stratified earth. These expressions involve infinite integrals over wave number, sometimes known as Sommerfield integrals. Numerical techniques used for evaluating these integrals are outlined. The problem of determining the current on a real antenna in the Earth, including the effect of insulation, is considered. Results are included for the fields of a point source in homogeneous and stratified earths and the field of a finite insulated dipole. The results are for electromagnetic propagation in the ELF-VLF range, but the codes also can address propagation problems at higher frequencies.

Data survey on the effect of product features on competitive advantage of selected firms in Nigeria.

PubMed

Olokundun, Maxwell; Iyiola, Oladele; Ibidunni, Stephen; Falola, Hezekiah; Salau, Odunayo; Amaihian, Augusta; Peter, Fred; Borishade, Taiye

2018-06-01

The main objective of this study was to present a data article that investigates the effect product features on firm's competitive advantage. Few studies have examined how the features of a product could help in driving the competitive advantage of a firm. Descriptive research method was used. Statistical Package for Social Sciences (SPSS 22) was engaged for analysis of one hundred and fifty (150) valid questionnaire which were completed by small business owners registered under small and medium scale enterprises development of Nigeria (SMEDAN). Stratified and simple random sampling techniques were employed; reliability and validity procedures were also confirmed. The field data set is made publicly available to enable critical or extended analysis.

Sticky trap and stem-tap sampling protocols for the Asian citrus psyllid (Hemiptera: Psyllidae)

USDA-ARS?s Scientific Manuscript database

Sampling statistics were obtained to develop a sampling protocol for estimating numbers of adult Diaphorina citri in citrus using two different sampling methods: yellow sticky traps and stem–tap samples. A 4.0 ha block of mature orange trees was stratified into ten 0.4 ha strata and sampled using...

Effects of Sampling Strategy, Detection Probability, and Independence of Counts on the Use of Point Counts

Treesearch

Grey W. Pendleton

1995-01-01

Many factors affect the use of point counts for monitoring bird populations, including sampling strategies, variation in detection rates, and independence of sample points. The most commonly used sampling plans are stratified sampling, cluster sampling, and systematic sampling. Each of these might be most useful for different objectives or field situations. Variation...

Residents Living in Residential Care Facilities: United States, 2010

MedlinePlus

... NSRCF used a stratified two-stage probability sample design. The first stage was the selection of RCFs ... was 99%. A detailed description of NSRCF sampling design, data collection, and procedures is provided both in ...

Half wavelength dipole antennas over stratified media

NASA Technical Reports Server (NTRS)

Latorraca, G. A.

1972-01-01

Theoretical solutions of the fields induced by half-wavelength, horizontal, electric field dipoles (HEDS) are determined based on studies of infinitesimal, horizontal, electric field dipoles over low loss plane-stratified media. To determine these solutions, an approximation to the current distribution of a half-wavelength HED is derived and experimentally verified. Traverse and antenna measurements obtained on the Athabasca Glacier in the summer of 1971 are related to the characteristics of the transmitting antenna design, and the measurement techniques and field equipment used in the glacier trials are described and evaluated.

Geohydrology and water quality of stratified-drift aquifers in the Saco and Ossipee River basins, east-central New Hampshire

USGS Publications Warehouse

Moore, R.B.; Medalie, Laura

1995-01-01

Stratified-drift aquifers discontinuously underlie 152.5 square miles of the Saco and Ossipee River Basins, which have a total drainage area of 869.4 square miles. Saturated thicknesses of stratified drift in the study area are locally greater than 280 feet, but generally are less. Transmissivity locally exceeds 8,000 feet squared per day but are generally less. About 93.6 square miles, or 10.8 percent of the study area, are identified as having transmissivity greater than 1,000 feet squared per day. The stratified-drift aquifer in Ossipee, Freedom, Effingham, Madison, and Tamworth was analyzed for the availability of ground water by use of transient simulations and a two-dimensional, finite-difference ground-water-flow model. The numerical -model results indicate that potential available water amounts in this aquifer are 7.72 million gallons per day. Sample results of water- quality analyses obtained from 25 test wells and 4 springs indicated that water was generally suitable for drinking and other domestic purposes. Concen- trations of dissolved constituents in ground-water samples are less than or meet U.S. Environmental Protection Agency (USEPA)primary and secondary drinking-water regulations. Concentrations of inorganic constituents that exceeded the USEPA's secondary regulations were chloride and sodium, iron manganese, and fluoride.

A random spatial sampling method in a rural developing nation

Treesearch

Michelle C. Kondo; Kent D.W. Bream; Frances K. Barg; Charles C. Branas

2014-01-01

Nonrandom sampling of populations in developing nations has limitations and can inaccurately estimate health phenomena, especially among hard-to-reach populations such as rural residents. However, random sampling of rural populations in developing nations can be challenged by incomplete enumeration of the base population. We describe a stratified random sampling method...

Representativeness-based sampling network design for the State of Alaska

Treesearch

Forrest M. Hoffman; Jitendra Kumar; Richard T. Mills; William W. Hargrove

2013-01-01

Resource and logistical constraints limit the frequency and extent of environmental observations, particularly in the Arctic, necessitating the development of a systematic sampling strategy to maximize coverage and objectively represent environmental variability at desired scales. A quantitative methodology for stratifying sampling domains, informing site selection,...

CTEPP STANDARD OPERATING PROCEDURE FOR SAMPLE SELECTION (SOP-1.10)

EPA Science Inventory

The procedures for selecting CTEPP study subjects are described in the SOP. The primary, county-level stratification is by region and urbanicity. Six sample counties in each of the two states (North Carolina and Ohio) are selected using stratified random sampling and reflect ...

Sampling High-Altitude and Stratified Mating Flights of Red Imported Fire Ant

USDA-ARS?s Scientific Manuscript database

With the exception of an airplane equipped with nets, no method has been developed that successfully samples red imported fire ant, Solenopsis invicta Buren, sexuals in mating/dispersal flights throughout their potential altitudinal trajectories. We developed and tested a method for sampling queens ...

Access to environmental resources and physical activity levels of adults in Hawaii.

PubMed

Geller, Karly S; Nigg, Claudio R; Ollberding, Nicholas J; Motl, Robert W; Horwath, Caroline; Dishman, Rodney K

2015-03-01

Examine associations between physical activity (PA) and spatial accessibility to environmental PA resources in Hawaii. Metabolic equivalents (METs) of mild, moderate, and strenuous PA were compared for accessibility with environmental PA resources within a population-based sample of Hawaiian adults (n = 381). Multiple linear regression estimated differences in PA levels for residing further from a PA resource or residing in an area with a greater number of resources. No associations were found in the total sample. Analyses within subsamples stratified by ethnicity revealed that greater spatial accessibility to a PA resource was positively associated with strenuous PA among Caucasians (P = .04) but negatively associated with moderate PA among Native Hawaiians (P = .00). The lack of association in the total sample may be a consequence of Hawaii's unique environment. Results of stratified sample analyses are unique, providing groundwork for future examinations within parallel environments and among similar ethnic groups. © 2012 APJPH.

Numerical modeling of subsurface communication, revision 1

NASA Astrophysics Data System (ADS)

Burke, G. J.; Dease, C. G.; Didwall, E. M.; Lytle, R. J.

1985-08-01

Techniques are described for numerical modeling of through-the-Earth communication. The basic problem considered is evaluation of the field at a surface or airborne station due to an antenna buried in the earth. Equations are given for the field of a point source in a homogeneous or stratified Earth. These expressions involve infinite integrals over wave number, sometimes known as Sommerfeld integrals. Numerical techniques used for evaluating these integrals are outlined. The problem of determining the current on a real antenna in the Earth, including the effect of insulation, is considered. Results are included for the fields of a point source in homogeneous and stratified earths and the field of a finite insulated dipole. The results are for electromagnetic propagation in the ELF-VLF range, but the codes also can address propagation problems at higher frequencies.

A unified model for reverberation and submerged object scattering in a stratified ocean waveguide.

PubMed

Makris, N C; Ratilal, P

2001-03-01

A unified model for reverberation and submerged target scattering in a stratified medium is developed from wave theory. The advantage of the unified approach is that it enables quantitative predictions to be made of the target-echo-to-reverberation ratio in an ocean waveguide. Analytic expressions are derived for both deterministic and stochastic scattering from the seafloor and subseafloor. Asymptotic techniques are used to derive expressions for the scattering of broadband waveforms from distant objects or surfaces. Expressions are then obtained for the scattered field after beamforming with a horizontal line array. The model is applied to problems of active detection in shallow water. Sample calculations for narrow-band signals indicate that the detection of submerged target echoes above diffuse seafloor reverberation is highly dependent upon water column and sediment stratification as well as array aperture, source, receiver, and target locations, in addition to the scattering properties of the target and seafloor. The model is also applied to determine the conditions necessary for echo returns from discrete geomorphologic features of the seafloor and subseafloor to stand prominently above diffuse seafloor reverberation. This has great relevance to the geologic clutter problem encountered by active sonar systems operating in shallow water, as well as to the remote sensing of underwater geomorphology.

Neoproterozoic cap-dolostone deposition in stratified glacial meltwater plume

NASA Astrophysics Data System (ADS)

Liu, Chao; Wang, Zhengrong; Raub, Timothy D.; Macdonald, Francis A.; Evans, David A. D.

2014-10-01

Neoproterozoic cap carbonates host distinctive geochemical and sedimentological features that reflect prevailing conditions in the aftermath of Snowball Earth. Interpretation of these features has remained contentious, with hypotheses hinging upon timescale and synchronicity of deposition, and whether or not geochemical signatures of cap carbonates represent those of a well-mixed ocean. Here we present new high-resolution Sr and Mg isotope results from basal Ediacaran cap dolostones in South Australia and Mongolia. Least-altered Sr and Mg isotope compositions of carbonates are identified through a novel incremental leaching technique that monitors the purity of a carbonate sample and the effects of diagenesis. These data can be explained by the formation of these cap dolostones involving two chemically distinct solutions, a glacial meltwater plume enriched in radiogenic Sr, and a saline ocean residue with relatively lower 87Sr/86Sr ratios. Model simulations suggest that these water bodies remained dynamically stratified during part of cap-dolostone deposition, most likely lasting for ∼8 thousand years. Our results can potentially reconcile previous conflicts between timescales estimated from physical mixing models and paleomagnetic constraints. Geochemical data from cap carbonates used to interpret the nature of Snowball Earth and its aftermath should be recast in terms of a chemically distinct meltwater plume.

A comparison of two sampling designs for fish assemblage assessment in a large river

USGS Publications Warehouse

Kiraly, Ian A.; Coghlan, Stephen M.; Zydlewski, Joseph D.; Hayes, Daniel

2014-01-01

We compared the efficiency of stratified random and fixed-station sampling designs to characterize fish assemblages in anticipation of dam removal on the Penobscot River, the largest river in Maine. We used boat electrofishing methods in both sampling designs. Multiple 500-m transects were selected randomly and electrofished in each of nine strata within the stratified random sampling design. Within the fixed-station design, up to 11 transects (1,000 m) were electrofished, all of which had been sampled previously. In total, 88 km of shoreline were electrofished during summer and fall in 2010 and 2011, and 45,874 individuals of 34 fish species were captured. Species-accumulation and dissimilarity curve analyses indicated that all sampling effort, other than fall 2011 under the fixed-station design, provided repeatable estimates of total species richness and proportional abundances. Overall, our sampling designs were similar in precision and efficiency for sampling fish assemblages. The fixed-station design was negatively biased for estimating the abundance of species such as Common Shiner Luxilus cornutus and Fallfish Semotilus corporalis and was positively biased for estimating biomass for species such as White Sucker Catostomus commersonii and Atlantic Salmon Salmo salar. However, we found no significant differences between the designs for proportional catch and biomass per unit effort, except in fall 2011. The difference observed in fall 2011 was due to limitations on the number and location of fixed sites that could be sampled, rather than an inherent bias within the design. Given the results from sampling in the Penobscot River, application of the stratified random design is preferable to the fixed-station design due to less potential for bias caused by varying sampling effort, such as what occurred in the fall 2011 fixed-station sample or due to purposeful site selection.

Stratified probabilistic bias analysis for BMI-related exposure misclassification in postmenopausal women.

PubMed

Banack, Hailey R; Stokes, Andrew; Fox, Matthew P; Hovey, Kathleen M; Cespedes-Feliciano, Elizabeth M; LeBlanc, Erin; Bird, Chloe; Caan, Bette J; Kroenke, Candyce H; Allison, Matthew A; Going, Scott B; Snetslaar, Linda; Cheng, Ting-Yuan David; Chlebowski, Rowan T; Stefanick, Marcia L; LaMonte, Michael J; Wactawski-Wende, Jean

2018-06-01

There is widespread concern about the use of body mass index (BMI) to define obesity status in postmenopausal women because it may not accurately represent an individual's true obesity status. The objective of the present study is to examine and adjust for exposure misclassification bias from using an indirect measure of obesity (BMI) compared with a direct measure of obesity (percent body fat). We used data from postmenopausal non-Hispanic black and non-Hispanic white women in the Women's Health Initiative (WHI; n=126,459). Within the WHI, a sample of 11,018 women were invited to participate in a sub-study involving dual-energy x-ray absorptiometry (DXA) scans. We examined indices of validity comparing BMI-defined obesity (≥30kg/m) with obesity defined by percent body fat. We then used probabilistic bias analysis models stratified by age and race to explore the effect of exposure misclassification on the obesity-mortality relationship. Validation analyses highlight that using a BMI cutpoint of 30 kg/m to define obesity in postmenopausal women is associated with poor validity. There were notable differences in sensitivity by age and race. Results from the stratified bias analysis demonstrated that failing to adjust for exposure misclassification bias results in attenuated estimates of the obesity-mortality relationship. For example, in non-Hispanic white women age 50-59, the conventional risk difference was 0.017 (95% CI 0.01, 0.023) and the bias-adjusted risk difference was 0.035 (95% SI 0.028, 0.043). These results demonstrate the importance of using quantitative bias analysis techniques to account for non-differential exposure misclassification of BMI-defined obesity.

Cost-effective sampling of ¹³⁷Cs-derived net soil redistribution: part 1--estimating the spatial mean across scales of variation.

PubMed

Li, Y; Chappell, A; Nyamdavaa, B; Yu, H; Davaasuren, D; Zoljargal, K

2015-03-01

The (137)Cs technique for estimating net time-integrated soil redistribution is valuable for understanding the factors controlling soil redistribution by all processes. The literature on this technique is dominated by studies of individual fields and describes its typically time-consuming nature. We contend that the community making these studies has inappropriately assumed that many (137)Cs measurements are required and hence estimates of net soil redistribution can only be made at the field scale. Here, we support future studies of (137)Cs-derived net soil redistribution to apply their often limited resources across scales of variation (field, catchment, region etc.) without compromising the quality of the estimates at any scale. We describe a hybrid, design-based and model-based, stratified random sampling design with composites to estimate the sampling variance and a cost model for fieldwork and laboratory measurements. Geostatistical mapping of net (1954-2012) soil redistribution as a case study on the Chinese Loess Plateau is compared with estimates for several other sampling designs popular in the literature. We demonstrate the cost-effectiveness of the hybrid design for spatial estimation of net soil redistribution. To demonstrate the limitations of current sampling approaches to cut across scales of variation, we extrapolate our estimate of net soil redistribution across the region, show that for the same resources, estimates from many fields could have been provided and would elucidate the cause of differences within and between regional estimates. We recommend that future studies evaluate carefully the sampling design to consider the opportunity to investigate (137)Cs-derived net soil redistribution across scales of variation. Copyright © 2014 Elsevier Ltd. All rights reserved.

Patterns in bacterial and archaeal community structure and diversity in western Beaufort Sea sediments and waters

NASA Astrophysics Data System (ADS)

Hamdan, L. J.; Sikaroodi, M.; Coffin, R. B.; Gillevet, P. M.

2010-12-01

A culture-independent phylogenetic study of microbial communities in water samples and sediment cores recovered from the Beaufort Sea slope east of Point Barrow, Alaska was conducted. The goal of the work was to describe community composition in sediment and water samples and determine the influence of local environmental conditions on microbial populations. Archaeal and bacterial community composition was studied using length heterogeneity-polymerase chain reaction (LH-PCR) and multitag pyrosequencing (MTPS). Sediment samples were obtained from three piston cores on the slope (~1000m depth) arrayed along an east-west transect and one core from a depth of approximately 2000m. Discrete water samples were obtained using a CTD-rosette from three locations adjacent to piston core sites. Water sample were selected at three discrete depths within a vertically stratified (density) water column. The microbial community in near surface waters was distinct from the community observed in deeper stratified layers of the water column. Multidimensional scaling analysis (MDS) revealed that water samples from mid and deep stratified layers bore high similarity to communities in cores collected in close proximity. Overall, the highest diversity (bacteria and archaea) was observed in a core which had elevated methane concentration relative to other locations. Geochemical (e.g., bulk organic and inorganic carbon pools, nutrients, metabolites) and physical data (e.g. depth, water content) were used to reveal the abiotic factors structuring microbial communities. The analysis indicates that sediment water content (porosity) and inorganic carbon concentration are the most significant structuring elements on Beaufort shelf sedimentary microbial communities.

A Matter of Classes: Stratifying Health Care Populations to Produce Better Estimates of Inpatient Costs

PubMed Central

Rein, David B

2005-01-01

Objective To stratify traditional risk-adjustment models by health severity classes in a way that is empirically based, is accessible to policy makers, and improves predictions of inpatient costs. Data Sources Secondary data created from the administrative claims from all 829,356 children aged 21 years and under enrolled in Georgia Medicaid in 1999. Study Design A finite mixture model was used to assign child Medicaid patients to health severity classes. These class assignments were then used to stratify both portions of a traditional two-part risk-adjustment model predicting inpatient Medicaid expenditures. Traditional model results were compared with the stratified model using actuarial statistics. Principal Findings The finite mixture model identified four classes of children: a majority healthy class and three illness classes with increasing levels of severity. Stratifying the traditional two-part risk-adjustment model by health severity classes improved its R2 from 0.17 to 0.25. The majority of additional predictive power resulted from stratifying the second part of the two-part model. Further, the preference for the stratified model was unaffected by months of patient enrollment time. Conclusions Stratifying health care populations based on measures of health severity is a powerful method to achieve more accurate cost predictions. Insurers who ignore the predictive advances of sample stratification in setting risk-adjusted premiums may create strong financial incentives for adverse selection. Finite mixture models provide an empirically based, replicable methodology for stratification that should be accessible to most health care financial managers. PMID:16033501

Evaluation of different approaches for identifying optimal sites to predict mean hillslope soil moisture content

NASA Astrophysics Data System (ADS)

Liao, Kaihua; Zhou, Zhiwen; Lai, Xiaoming; Zhu, Qing; Feng, Huihui

2017-04-01

The identification of representative soil moisture sampling sites is important for the validation of remotely sensed mean soil moisture in a certain area and ground-based soil moisture measurements in catchment or hillslope hydrological studies. Numerous approaches have been developed to identify optimal sites for predicting mean soil moisture. Each method has certain advantages and disadvantages, but they have rarely been evaluated and compared. In our study, surface (0-20 cm) soil moisture data from January 2013 to March 2016 (a total of 43 sampling days) were collected at 77 sampling sites on a mixed land-use (tea and bamboo) hillslope in the hilly area of Taihu Lake Basin, China. A total of 10 methods (temporal stability (TS) analyses based on 2 indices, K-means clustering based on 6 kinds of inputs and 2 random sampling strategies) were evaluated for determining optimal sampling sites for mean soil moisture estimation. They were TS analyses based on the smallest index of temporal stability (ITS, a combination of the mean relative difference and standard deviation of relative difference (SDRD)) and based on the smallest SDRD, K-means clustering based on soil properties and terrain indices (EFs), repeated soil moisture measurements (Theta), EFs plus one-time soil moisture data (EFsTheta), and the principal components derived from EFs (EFs-PCA), Theta (Theta-PCA), and EFsTheta (EFsTheta-PCA), and global and stratified random sampling strategies. Results showed that the TS based on the smallest ITS was better (RMSE = 0.023 m3 m-3) than that based on the smallest SDRD (RMSE = 0.034 m3 m-3). The K-means clustering based on EFsTheta (-PCA) was better (RMSE <0.020 m3 m-3) than these based on EFs (-PCA) and Theta (-PCA). The sampling design stratified by the land use was more efficient than the global random method. Forty and 60 sampling sites are needed for stratified sampling and global sampling respectively to make their performances comparable to the best K-means method (EFsTheta-PCA). Overall, TS required only one site, but its accuracy was limited. The best K-means method required <8 sites and yielded high accuracy, but extra soil and terrain information is necessary when using this method. The stratified sampling strategy can only be used if no pre-knowledge about soil moisture variation is available. This information will help in selecting the optimal methods for estimation the area mean soil moisture.

Reuse, Recycle, Reweigh: Combating Influenza through Efficient Sequential Bayesian Computation for Massive Data.

PubMed

Tom, Jennifer A; Sinsheimer, Janet S; Suchard, Marc A

Massive datasets in the gigabyte and terabyte range combined with the availability of increasingly sophisticated statistical tools yield analyses at the boundary of what is computationally feasible. Compromising in the face of this computational burden by partitioning the dataset into more tractable sizes results in stratified analyses, removed from the context that justified the initial data collection. In a Bayesian framework, these stratified analyses generate intermediate realizations, often compared using point estimates that fail to account for the variability within and correlation between the distributions these realizations approximate. However, although the initial concession to stratify generally precludes the more sensible analysis using a single joint hierarchical model, we can circumvent this outcome and capitalize on the intermediate realizations by extending the dynamic iterative reweighting MCMC algorithm. In doing so, we reuse the available realizations by reweighting them with importance weights, recycling them into a now tractable joint hierarchical model. We apply this technique to intermediate realizations generated from stratified analyses of 687 influenza A genomes spanning 13 years allowing us to revisit hypotheses regarding the evolutionary history of influenza within a hierarchical statistical framework.

Reuse, Recycle, Reweigh: Combating Influenza through Efficient Sequential Bayesian Computation for Massive Data

PubMed Central

Tom, Jennifer A.; Sinsheimer, Janet S.; Suchard, Marc A.

2015-01-01

Massive datasets in the gigabyte and terabyte range combined with the availability of increasingly sophisticated statistical tools yield analyses at the boundary of what is computationally feasible. Compromising in the face of this computational burden by partitioning the dataset into more tractable sizes results in stratified analyses, removed from the context that justified the initial data collection. In a Bayesian framework, these stratified analyses generate intermediate realizations, often compared using point estimates that fail to account for the variability within and correlation between the distributions these realizations approximate. However, although the initial concession to stratify generally precludes the more sensible analysis using a single joint hierarchical model, we can circumvent this outcome and capitalize on the intermediate realizations by extending the dynamic iterative reweighting MCMC algorithm. In doing so, we reuse the available realizations by reweighting them with importance weights, recycling them into a now tractable joint hierarchical model. We apply this technique to intermediate realizations generated from stratified analyses of 687 influenza A genomes spanning 13 years allowing us to revisit hypotheses regarding the evolutionary history of influenza within a hierarchical statistical framework. PMID:26681992

SCIENTIFIC PAPER PRESENTATION DURING CONCURRENT INTEREST SESSION. Community Health Nursing (Speciality). Iron-deficiency anemia.

PubMed

Kala, K

2015-01-01

Iron deficiency anaemia is the most common form of malnutrition in the world. The global prevalence of anaemia mainly in South East Asia is 65.5 percent, in India 56 percent among adolescent girls. A study conducted to assess the effectiveness of structured teaching programme on knowledge and attitude of adolescent girls in prevention of iron and folic acid deficiency anaemia at a selected corporation school. It adopted one group pre-test post-test design with 60 samples selected by employing stratified random sampling technique. The study revealed that during pre-test 90 percent of them had inadequate knowledge and 65 percent of them had unfavourable attitude towards iron and folic acid deficiency anaemia. After the structured teaching programme the knowledge and attitude was improved (73% had adequate knowledge and 79% had most favourable attitude). Overall the structured teaching programme was found effective in improving the knowledge and attitude of adolescent girls in prevention of iron and folic acid deficiency anaemia.

Analysis of water ice and water ice/soil mixtures using laser-induced breakdown spectroscopy: application to Mars polar exploration.

PubMed

Arp, Zane A; Cremers, David A; Wiens, Roger C; Wayne, David M; Sallé, Béatrice; Maurice, Sylvestre

2004-08-01

Recently, laser-induced breakdown spectroscopy (LIBS) has been developed for the elemental analysis of geological samples for application to space exploration. There is also interest in using the technique for the analysis of water ice and ice/dust mixtures located at the Mars polar regions. The application is a compact instrument for a lander or rover to the Martian poles to interrogate stratified layers of ice and dusts that contain a record of past geologic history, believed to date back several million years. Here we present results of a study of the use of LIBS for the analysis of water ice and ice/dust mixtures in situ and at short stand-off distances (< 6.5 m) using experimental parameters appropriate for a compact instrument. Characteristics of LIBS spectra of water ice, ice/soil mixtures, element detection limits, and the ability to ablate through ice samples to monitor subsurface dust deposits are discussed.

Sociodemographic factors associated with self-reported exercise and physical activity behaviors and attitudes of South Australians: results of a population-based survey.

PubMed

Thomas, Susie; Halbert, Julie; Mackintosh, Shylie; Quinn, Stephen; Crotty, Maria

2012-03-01

To determine self-reported physical activity barriers, behaviors, and beliefs about exercise of a representative sample and to identify associated sociodemographic factors. Face-to-face interviews conducted between September and December 2008, using a random stratified sampling technique. Barriers injury and illness were associated with being older, single, and not engaged in full-time work; lack of time was associated with being married, younger, female, and working full-time; and lack of motivation and cost were associated with being younger than 65 years. Advancing age was significantly associated (p < .001) with reduced physical activity. Factors including age, education, marital status, and area of residence were all associated with preferences for environment to exercise in, while all age groups (74%) felt that walking was the most important type of exercise for older adults. A better understanding of these factors may improve uptake of and adherence to exercise programs across the ages.

Endoscopic OCT for in-vivo imaging of precancer and cancer states of human mucosa

NASA Astrophysics Data System (ADS)

Sergeev, Alexander M.; Gelikonov, Valentin M.; Gelikonov, Grigory V.; Feldchtein, Felix I.; Kuranov, Roman V.; Gladkova, Natalia D.; Shakhova, Natalia M.; Kuznetzova, Irina N.; Snopova, Ludmila; Denisenko, Arkady; Almasov, Valentin

1998-01-01

First results of endoscopic applications of optical coherence tomography for in vivo studies of human mucosa in gastrointestinal and genital tracts are presented. A novel endoscopic OCT system has ben created that is based on the integration of a sampling arm of an all-optical-fiber interferometer into standard endoscopic devices using their biopsy channel to transmit low-coherence radiation to investigated tissue. We have studied mucous membranes of esophagus, stomach and uterine cervix as typical localization for carcinomatous processes. Images of tumor tissues versus healthy tissues have been recorded and analyzed. Violations of well-defined stratified healthy mucosa structure in cancerous tissue is distinctly seen by EOCT, thus making this technique promising for early diagnosis of tumors and precise guiding of excisional biopsy.

Data article on the effect of work engagement strategies on faculty staff behavioural outcomes in private universities.

PubMed

Falola, Hezekiah Olubusayo; Olokundun, Maxwell Ayodele; Salau, Odunayo Paul; Oludayo, Olumuyiwa Akinrole; Ibidunni, Ayodotun Stephen

2018-06-01

The main objective of this study was to present a data article that investigate the effect of work engagement strategies on faculty behavioural outcomes. Few studies analyse how work engagement strategies could help in driving standard work behaviour particularly in higher institutions. In an attempt to bridge this gap, this study was carried out using descriptive research method and Structural Equation Model (AMOS 22) for the analysis of four hundred and forty one (441) valid questionnaire which were completed by the faculty members of the six selected private universities in Nigeria using stratified and simple random sampling techniques. Factor model which shows high-reliability and good fit was generated, while construct validity was provided through convergent and discriminant analyses.

Monitoring land cover changes by remote sensing in north west Egypt

NASA Astrophysics Data System (ADS)

Richards, Timothy Steven

The Mediterratiean coastal strip of Egypt is a semi-arid environment which supports a variety of agricultural practices ranging from irrigated sedentary agriculture to semi-nomadic pastoralism. The sedentarisation of the nomadic Bedouin coupled with an increase in population of both people and livestock and a decrease in the extent of the rangelands, has resulted in severe pressure being exerted upon the environment. Satellite remote sensing of vegetation offers the potential to aid regional management by complementing conventional techniques of vegetation mapping and monitoring. This thesis examines the different techniques available for vegetation mapping using visible and near infrared spectral wave bands. The different techniques available for vegetation mapping using remotely sensed data are reviewed and discussed with reference to semi-arid environments. The underlying similarity of many of the techniques is emphasised and their individual merits discussed. The spectral feature-space of Landsat data of two representative study areas in northern Egypt is explored and examined using graphical techniques and principal components analysis. Hand held radiometric field data are also presented for individual soil types within the region. It is proposed that by using reference data for individual soil types, improved estimates of vegetation cover can be ascertained. A number of radiometric corrections are applied to the digital Landsat data in order to convert the arbitrary digital values of the different spectral bands into physical values of reflectance. The effect of this standardization on the principal components is examined. The stratified approach to vegetation mapping which was explored using the field data is applied in turn to the digital Landsat images. Whilst the stratified approach was not found to offer significant advantages over the non-stratified approach in this case, the analysis does serve to provide an accurate datum against which to measure vegetation. In conclusion a satellite based system for operational vegetation monitoring is proposed.

The experimentation of LC7E learning model on the linear program material in terms of interpersonal intelligence on Wonogiri vocational school students

NASA Astrophysics Data System (ADS)

Antinah; Kusmayadi, T. A.; Husodo, B.

2018-05-01

This study aims to determine the effect of learning model on student achievement in terms of interpersonal intelligence. The compared learning models are LC7E and Direct learning model. This type of research is a quasi-experimental with 2x3 factorial design. The population in this study is a Grade XI student of Wonogiri Vocational Schools. The sample selection had done by stratified cluster random sampling. Data collection technique used questionnaires, documentation and tests. The data analysis technique used two different unequal cell variance analysis which previously conducted prerequisite analysis for balance test, normality test and homogeneity test. he conclusions of this research are: 1) student learning achievement of mathematics given by LC7E learning model is better when compared with direct learning; 2) Mathematics learning achievement of students who have a high level of interpersonal intelligence is better than students with interpersonal intelligence in medium and low level. Students' mathematics learning achievement with interpersonal level of intelligence is better than those with low interpersonal intelligence on linear programming; 3) LC7E learning model resulted better on mathematics learning achievement compared with direct learning model for each category of students’ interpersonal intelligence level on linear program material.

The experimentation of LC7E learning model on the linear program material in terms of interpersonal intelligence on Wonogiri Vocational School students

NASA Astrophysics Data System (ADS)

Antinah; Kusmayadi, T. A.; Husodo, B.

2018-03-01

This study aimed to determine the effect of learning model on student achievement in terms of interpersonal intelligence. The compared learning models are LC7E and Direct learning model. This type of research is a quasi-experimental with 2x3 factorial design. The population in this study is a Grade XI student of Wonogiri Vocational Schools. The sample selection had done by stratified cluster random sampling. Data collection technique used questionnaires, documentation and tests. The data analysis technique used two different unequal cell variance analysis which previously conducted prerequisite analysis for balance test, normality test and homogeneity test. he conclusions of this research are: 1) student learning achievement of mathematics given by LC7E learning model is better when compared with direct learning; 2) Mathematics learning achievement of students who have a high level of interpersonal intelligence is better than students with interpersonal intelligence in medium and low level. Students’ mathematics learning achievement with interpersonal level of intelligence is better than those with low interpersonal intelligence on linear programming; 3) LC7E learning model resulted better on mathematics learning achievement compared with direct learning model for each category of students’ interpersonal intelligence level on linear program material.

Cherry-picking functionally relevant substates from long md trajectories using a stratified sampling approach.

PubMed

Chandramouli, Balasubramanian; Mancini, Giordano

2016-01-01

Classical Molecular Dynamics (MD) simulations can provide insights at the nanoscopic scale into protein dynamics. Currently, simulations of large proteins and complexes can be routinely carried out in the ns-μs time regime. Clustering of MD trajectories is often performed to identify selective conformations and to compare simulation and experimental data coming from different sources on closely related systems. However, clustering techniques are usually applied without a careful validation of results and benchmark studies involving the application of different algorithms to MD data often deal with relatively small peptides instead of average or large proteins; finally clustering is often applied as a means to analyze refined data and also as a way to simplify further analysis of trajectories. Herein, we propose a strategy to classify MD data while carefully benchmarking the performance of clustering algorithms and internal validation criteria for such methods. We demonstrate the method on two showcase systems with different features, and compare the classification of trajectories in real and PCA space. We posit that the prototype procedure adopted here could be highly fruitful in clustering large trajectories of multiple systems or that resulting especially from enhanced sampling techniques like replica exchange simulations. Copyright: © 2016 by Fabrizio Serra editore, Pisa · Roma.

Should Torsion Balance Technique Continue to be Taught to Pharmacy Students?

PubMed

Bilger, Rhonda; Chereson, Rasma; Salama, Noha Nabil

2017-06-01

Objective. To determine the types of balances used in compounding pharmacies: torsion or digital. Methods. A survey was mailed to the pharmacist-in-charge at 698 pharmacies, representing 47% of the pharmacies in Missouri as of July 2013. The pharmacies were randomly selected and stratified by region into eight regions to ensure a representative sample. Information was gathered regarding the type and use of balances and pharmacists' perspectives on the need to teach torsion balance technique to pharmacy students. Results. The response rate for the survey was 53.3%. Out of the total responses received, those pharmacies having a torsion balance, digital balance or both were 46.8%, 27.4% and 11.8%, respectively. About 68.3% of respondents compound prescriptions. The study showed that 52% of compounding pharmacies use torsion balances in their practice. Of those with a balance in their pharmacy, 65.6% favored continuation of torsion balance instruction. Conclusions. Digital balances have become increasingly popular and have replaced torsion balances in some pharmacies, especially those that compound a significant number of prescriptions. The results of this study indicate that torsion balances remain integral to compounding practice. Therefore, students should continue being taught torsion balance technique at the college.

Should Torsion Balance Technique Continue to be Taught to Pharmacy Students?

PubMed Central

Bilger, Rhonda; Chereson, Rasma

2017-01-01

Objective. To determine the types of balances used in compounding pharmacies: torsion or digital. Methods. A survey was mailed to the pharmacist-in-charge at 698 pharmacies, representing 47% of the pharmacies in Missouri as of July 2013. The pharmacies were randomly selected and stratified by region into eight regions to ensure a representative sample. Information was gathered regarding the type and use of balances and pharmacists’ perspectives on the need to teach torsion balance technique to pharmacy students. Results. The response rate for the survey was 53.3%. Out of the total responses received, those pharmacies having a torsion balance, digital balance or both were 46.8%, 27.4% and 11.8%, respectively. About 68.3% of respondents compound prescriptions. The study showed that 52% of compounding pharmacies use torsion balances in their practice. Of those with a balance in their pharmacy, 65.6% favored continuation of torsion balance instruction. Conclusions. Digital balances have become increasingly popular and have replaced torsion balances in some pharmacies, especially those that compound a significant number of prescriptions. The results of this study indicate that torsion balances remain integral to compounding practice. Therefore, students should continue being taught torsion balance technique at the college. PMID:28720913

Assessment of fracture risk: value of random population-based samples--the Geelong Osteoporosis Study.

PubMed

Henry, M J; Pasco, J A; Seeman, E; Nicholson, G C; Sanders, K M; Kotowicz, M A

2001-01-01

Fracture risk is determined by bone mineral density (BMD). The T-score, a measure of fracture risk, is the position of an individual's BMD in relation to a reference range. The aim of this study was to determine the magnitude of change in the T-score when different sampling techniques were used to produce the reference range. Reference ranges were derived from three samples, drawn from the same region: (1) an age-stratified population-based random sample, (2) unselected volunteers, and (3) a selected healthy subset of the population-based sample with no diseases or drugs known to affect bone. T-scores were calculated using the three reference ranges for a cohort of women who had sustained a fracture and as a group had a low mean BMD (ages 35-72 yr; n = 484). For most comparisons, the T-scores for the fracture cohort were more negative using the population reference range. The difference in T-scores reached 1.0 SD. The proportion of the fracture cohort classified as having osteoporosis at the spine was 26, 14, and 23% when the population, volunteer, and healthy reference ranges were applied, respectively. The use of inappropriate reference ranges results in substantial changes to T-scores and may lead to inappropriate management.

Irradiance attenuation coefficient in a stratified ocean - A local property of the medium

NASA Technical Reports Server (NTRS)

Gordon, H. R.

1980-01-01

The influence of optically important constituents of water on the absorption (a) and scattering (b) coefficients and the backscattering probability is considered, with emphasis placed on measuring the volume scattering function (B/theta/). Two stratification models are examined; one in which the phase function (B(theta)/b) is depth independent and only b/c is allowed to vary with optical depth, and the other in which both b/c and the phase function depend on depth. The results demonstrate that Gordon's (1977) technique of estimating a and b is applicable without change to a stratified ocean.

Hierarchical spatial capture-recapture models: Modeling population density from stratified populations

USGS Publications Warehouse

Royle, J. Andrew; Converse, Sarah J.

2014-01-01

Capture–recapture studies are often conducted on populations that are stratified by space, time or other factors. In this paper, we develop a Bayesian spatial capture–recapture (SCR) modelling framework for stratified populations – when sampling occurs within multiple distinct spatial and temporal strata.We describe a hierarchical model that integrates distinct models for both the spatial encounter history data from capture–recapture sampling, and also for modelling variation in density among strata. We use an implementation of data augmentation to parameterize the model in terms of a latent categorical stratum or group membership variable, which provides a convenient implementation in popular BUGS software packages.We provide an example application to an experimental study involving small-mammal sampling on multiple trapping grids over multiple years, where the main interest is in modelling a treatment effect on population density among the trapping grids.Many capture–recapture studies involve some aspect of spatial or temporal replication that requires some attention to modelling variation among groups or strata. We propose a hierarchical model that allows explicit modelling of group or strata effects. Because the model is formulated for individual encounter histories and is easily implemented in the BUGS language and other free software, it also provides a general framework for modelling individual effects, such as are present in SCR models.

Internet Usage Habits and Cyberbullying Related Opinions of Secondary School Students

ERIC Educational Resources Information Center

Sentürk, Sener; Bayat, Seher

2016-01-01

The purpose of this research is to examine the internet usage habits of secondary school students and their awareness of cyberbullying in terms of different variables. Of the probabilistic sampling methods, research sampling identified by stratified sampling method has been formed by 559 students from two branches (56 branches in total) selected…

RECAL: A Computer Program for Selecting Sample Days for Recreation Use Estimation

Treesearch

D.L. Erickson; C.J. Liu; H. Ken Cordell; W.L. Chen

1980-01-01

Recreation Calendar (RECAL) is a computer program in PL/I for drawing a sample of days for estimating recreation use. With RECAL, a sampling period of any length may be chosen; simple random, stratified random, and factorial designs can be accommodated. The program randomly allocates days to strata and locations.

77 FR 2697 - Proposed Information Collection; Comment Request; Annual Services Report

Federal Register 2010, 2011, 2012, 2013, 2014

2012-01-19

... and from a sample of small- and medium-sized businesses selected using a stratified sampling procedure... be canvassed when the sample is re-drawn, while nearly all of the small- and medium-sized firms from...); Educational Services (NAICS 61); Health Care and Social Assistance (NAICS 62); Arts, Entertainment, and...

Evaluation of Students' Perceptions about Efficiency of Educational Club Practices in Primary Schools

ERIC Educational Resources Information Center

Gelen, Ismail; Onay, Ihsan; Varol, Volkan

2014-01-01

The purpose of this study is to examine the efficiency of "Educational Club Practices" that has been in Elementary School program since 2005-2006, by examining the attitudes of students about "Educational Club Practices". Sample was selected in two steps. First, stratified sampling was employed and then random sampling was…

Sample Selection in Randomized Experiments: A New Method Using Propensity Score Stratified Sampling

ERIC Educational Resources Information Center

Tipton, Elizabeth; Hedges, Larry; Vaden-Kiernan, Michael; Borman, Geoffrey; Sullivan, Kate; Caverly, Sarah

2014-01-01

Randomized experiments are often seen as the "gold standard" for causal research. Despite the fact that experiments use random assignment to treatment conditions, units are seldom selected into the experiment using probability sampling. Very little research on experimental design has focused on how to make generalizations to well-defined…

A New Stratified Sampling Procedure which Decreases Error Estimation of Varroa Mite Number on Sticky Boards.

PubMed

Kretzschmar, A; Durand, E; Maisonnasse, A; Vallon, J; Le Conte, Y

2015-06-01

A new procedure of stratified sampling is proposed in order to establish an accurate estimation of Varroa destructor populations on sticky bottom boards of the hive. It is based on the spatial sampling theory that recommends using regular grid stratification in the case of spatially structured process. The distribution of varroa mites on sticky board being observed as spatially structured, we designed a sampling scheme based on a regular grid with circles centered on each grid element. This new procedure is then compared with a former method using partially random sampling. Relative error improvements are exposed on the basis of a large sample of simulated sticky boards (n=20,000) which provides a complete range of spatial structures, from a random structure to a highly frame driven structure. The improvement of varroa mite number estimation is then measured by the percentage of counts with an error greater than a given level. © The Authors 2015. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Cost-effectiveness of risk stratified followup after urethral reconstruction: a decision analysis.

PubMed

Belsante, Michael J; Zhao, Lee C; Hudak, Steven J; Lotan, Yair; Morey, Allen F

2013-10-01

We propose a novel risk stratified followup protocol for use after urethroplasty and explore potential cost savings. Decision analysis was performed comparing a symptom based, risk stratified protocol for patients undergoing excision and primary anastomosis urethroplasty vs a standard regimen of close followup for urethroplasty. Model assumptions included that excision and primary anastomosis has a 94% success rate, 11% of patients with successful urethroplasty had persistent lower urinary tract symptoms requiring cystoscopic evaluation, patients in whom treatment failed undergo urethrotomy and patients with recurrence on symptom based surveillance have a delayed diagnosis requiring suprapubic tube drainage. The Nationwide Inpatient Sample from 2010 was queried to identify the number of urethroplasties performed per year in the United States. Costs were obtained based on Medicare reimbursement rates. The 5-year cost of a symptom based, risk stratified followup protocol is $430 per patient vs $2,827 per patient using standard close followup practice. An estimated 7,761 urethroplasties were performed in the United States in 2010. Assuming that 60% were excision and primary anastomosis, and with more than 5 years of followup, the risk stratified protocol was projected to yield an estimated savings of $11,165,130. Sensitivity analysis showed that the symptom based, risk stratified followup protocol was far more cost-effective than standard close followup in all settings. Less than 1% of patients would be expected to have an asymptomatic recurrence using the risk stratified followup protocol. A risk stratified, symptom based approach to urethroplasty followup would produce a significant reduction in health care costs while decreasing unnecessary followup visits, invasive testing and radiation exposure. Copyright © 2013 American Urological Association Education and Research, Inc. Published by Elsevier Inc. All rights reserved.

Remote Sensing, Sampling and Simulation Applications in Analyses of Insect Dispersion and Abundance in Cotton

Treesearch

J. L. Willers; J. M. McKinion; J. N. Jenkins

2006-01-01

Simulation was employed to create stratified simple random samples of different sample unit sizes to represent tarnished plant bug abundance at different densities within various habitats of simulated cotton fields. These samples were used to investigate dispersion patterns of this cotton insect. It was found that the assessment of spatial pattern varied as a function...

Spectral reflectance of surface soils: Relationships with some soil properties

NASA Technical Reports Server (NTRS)

Kiesewetter, C. H.

1983-01-01

Using a published atlas of reflectance curves and physicochemical properties of soils, a statistical analysis was carried out. Reflectance bands which correspond to five of the wavebands used by NASA's Thematic Mapper were examined for relationships to specific soil properties. The properties considered in this study include: Sand Content, Silt Content, Clay Content, Organic Matter Content, Cation Exchange Capacity, Iron Oxide Content and Moisture Content. Regression of these seven properties on the mean values of five TM bands produced results that indicate that the predictability of the properties can be increased by stratifying the data. The data was stratified by parent material, taxonomic order, temperature zone, moisture zone and climate (combined temperature and moisture). The best results were obtained when the sample was examined by climatic classes. The middle Infra-red bands, 5 and 7, as well as the visible bands, 2 and 3, are significant in the model. The near Infra-red band, band 4, is almost as useful and should be included in any studies. General linear modeling procedures examined relationships of the seven properties with certain wavebands in the stratified samples.

Testing homogeneity of proportion ratios for stratified correlated bilateral data in two-arm randomized clinical trials.

PubMed

Pei, Yanbo; Tian, Guo-Liang; Tang, Man-Lai

2014-11-10

Stratified data analysis is an important research topic in many biomedical studies and clinical trials. In this article, we develop five test statistics for testing the homogeneity of proportion ratios for stratified correlated bilateral binary data based on an equal correlation model assumption. Bootstrap procedures based on these test statistics are also considered. To evaluate the performance of these statistics and procedures, we conduct Monte Carlo simulations to study their empirical sizes and powers under various scenarios. Our results suggest that the procedure based on score statistic performs well generally and is highly recommended. When the sample size is large, procedures based on the commonly used weighted least square estimate and logarithmic transformation with Mantel-Haenszel estimate are recommended as they do not involve any computation of maximum likelihood estimates requiring iterative algorithms. We also derive approximate sample size formulas based on the recommended test procedures. Finally, we apply the proposed methods to analyze a multi-center randomized clinical trial for scleroderma patients. Copyright © 2014 John Wiley & Sons, Ltd.

In-hospital fall-risk screening in 4,735 geriatric patients from the LUCAS project.

PubMed

Neumann, L; Hoffmann, V S; Golgert, S; Hasford, J; Von Renteln-Kruse, W

2013-03-01

In-hospital falls in older patients are frequent, but the identification of patients at risk of falling is challenging. Aim of this study was to improve the identification of high-risk patients. Therefore, a simplified screening-tool was developed, validated, and compared to the STRATIFY predictive accuracy. Retrospective analysis of 4,735 patients; evaluation of predictive accuracy of STRATIFY and its single risk factors, as well as age, gender and psychotropic medication; splitting the dataset into a learning and a validation sample for modelling fall-risk screening and independent, temporal validation. Geriatric clinic at an academic teaching hospital in Hamburg, Germany. 4,735 hospitalised patients ≥65 years. Sensitivity, specificity, positive and negative predictive value, Odds Ratios, Youden-Index and the rates of falls and fallers were calculated. There were 10.7% fallers, and the fall rate was 7.9/1,000 hospital days. In the learning sample, mental alteration (OR 2.9), fall history (OR 2.1), and insecure mobility (Barthel-Index items 'transfer' + 'walking' score = 5, 10 or 15) (OR 2.3) had the most strongest association to falls. The LUCAS Fall-Risk Screening uses these risk factors, and patients with ≥2 risk factors contributed to the high-risk group (30.9%). In the validation sample, STRATIFY SENS was 56.8, SPEC 59.6, PPV 13.5 and NPV 92.6 vs. LUCAS Fall-Risk Screening was SENS 46.0, SPEC 71.1, PPV 14.9 and NPV 92.3. Both the STRATIFY and the LUCAS Fall-Risk Screening showed comparable results in defining a high-risk group. Impaired mobility and cognitive status were closely associated to falls. The results do underscore the importance of functional status as essential fall-risk factor in older hospitalised patients.

Quantifying Uncertainties from Presence Data Sampling Methods for Species Distribution Modeling: Focused on Vegetation.

NASA Astrophysics Data System (ADS)

Sung, S.; Kim, H. G.; Lee, D. K.; Park, J. H.; Mo, Y.; Kil, S.; Park, C.

2016-12-01

The impact of climate change has been observed throughout the globe. The ecosystem experiences rapid changes such as vegetation shift, species extinction. In these context, Species Distribution Model (SDM) is one of the popular method to project impact of climate change on the ecosystem. SDM basically based on the niche of certain species with means to run SDM present point data is essential to find biological niche of species. To run SDM for plants, there are certain considerations on the characteristics of vegetation. Normally, to make vegetation data in large area, remote sensing techniques are used. In other words, the exact point of presence data has high uncertainties as we select presence data set from polygons and raster dataset. Thus, sampling methods for modeling vegetation presence data should be carefully selected. In this study, we used three different sampling methods for selection of presence data of vegetation: Random sampling, Stratified sampling and Site index based sampling. We used one of the R package BIOMOD2 to access uncertainty from modeling. At the same time, we included BioCLIM variables and other environmental variables as input data. As a result of this study, despite of differences among the 10 SDMs, the sampling methods showed differences in ROC values, random sampling methods showed the lowest ROC value while site index based sampling methods showed the highest ROC value. As a result of this study the uncertainties from presence data sampling methods and SDM can be quantified.

Stratified sampling design based on data mining.

PubMed

Kim, Yeonkook J; Oh, Yoonhwan; Park, Sunghoon; Cho, Sungzoon; Park, Hayoung

2013-09-01

To explore classification rules based on data mining methodologies which are to be used in defining strata in stratified sampling of healthcare providers with improved sampling efficiency. We performed k-means clustering to group providers with similar characteristics, then, constructed decision trees on cluster labels to generate stratification rules. We assessed the variance explained by the stratification proposed in this study and by conventional stratification to evaluate the performance of the sampling design. We constructed a study database from health insurance claims data and providers' profile data made available to this study by the Health Insurance Review and Assessment Service of South Korea, and population data from Statistics Korea. From our database, we used the data for single specialty clinics or hospitals in two specialties, general surgery and ophthalmology, for the year 2011 in this study. Data mining resulted in five strata in general surgery with two stratification variables, the number of inpatients per specialist and population density of provider location, and five strata in ophthalmology with two stratification variables, the number of inpatients per specialist and number of beds. The percentages of variance in annual changes in the productivity of specialists explained by the stratification in general surgery and ophthalmology were 22% and 8%, respectively, whereas conventional stratification by the type of provider location and number of beds explained 2% and 0.2% of variance, respectively. This study demonstrated that data mining methods can be used in designing efficient stratified sampling with variables readily available to the insurer and government; it offers an alternative to the existing stratification method that is widely used in healthcare provider surveys in South Korea.

The Study of Literacy Reinforcement of Science Teachers in Implementing 2013 Curriculum

NASA Astrophysics Data System (ADS)

Dewi, W. S.; Festiyed, F.; Hamdi, H.; Sari, S. Y.

2018-04-01

This research aims to study and collect data comprehensively, new and actual about science literacy to improve the ability of educators in implementing the 2013 Curriculum at Junior High School Padang Pariaman District. The specific benefit of this research is to give description and to know the problem of science literacy problem in interaction among teacher, curriculum, facilities and infrastructure, evaluation, learning technology and students. This study uses explorative in deep study approach, studying and collecting data comprehensively from the interaction of education process components (curriculum, educator, learner, facilities and infrastructure, learning media technology, and evaluation) that influence the science literacy. This research was conducted in the districts of Padang Pariaman consisting of 17 subdistricts and 84 junior high schools managed by the government and private. The sample of this research is science teachers of Padang Pariaman District with sampling technique is stratified random sampling. The instrument used in this study is a questionnaire to the respondents. Research questionnaire data are processed by percentage techniques (quantitative). The results of this study explain that the understanding of science teachers in Padang Pariaman District towards the implementation of 2013 Curriculum is still lacking. The science teachers of Padang Pariaman District have not understood the scientific approach and the effectiveness of 2013 Curriculum in shaping the character of the students. To improve the understanding of the implementation of Curriculum 2013, it is necessary to strengthen the literacy toward science teachers at the Junior High School level in Padang Pariaman District.

An interpretation of the spectral properties of hot hydrogen-rich white dwarfs with stratified H/He model atmospheres

NASA Technical Reports Server (NTRS)

Vennes, Stephane; Fontaine, Gilles

1992-01-01

A grid of stratified H/He model atmospheres applicable to the interpretation of the spectral properties of hot H-rich white dwarfs (WDs) is computed. Samples of hot DA WDs observed with Exosat and Einstein are analyzed using the models. Six out of six objects with T(eff) = 35,000 K or less do not show a EUV/soft X-ray flux deficiency and therefore can be understood solely in terms of pure hydrogen atmospheres. A majority of DA WDs hotter than this value do show a flux deficiency and thus require the presence of some absorbers in their atmospheres. It is shown that the Exosat broadband photometry of Feige 24 and G191 B2B cannot be explained in terms of stratified atmospheres. Absorption by heavy elements is certainly responsible for the required EUV/soft X-ray opacity source in these cases. However, the Exosat data are consistent with the hypothesis of stratified atmospheres in the four remaining objects.

The linear trend of headache prevalence and some headache features in school children.

PubMed

Ozge, Aynur; Buğdayci, Resul; Saşmaz, Tayyar; Kaleağasi, Hakan; Kurt, Oner; Karakelle, Ali; Siva, Aksel

2007-04-01

The objectives of this study were to determine the age and sex dependent linear trend of recurrent headache prevalence in schoolchildren in Mersin. A stratified sample composed of 5562 children; detailed characteristics were previously published. In this study the prevalence distribution of headache by age and sex showed a peak in the female population at the age of 11 (27.2%) with a plateau in the following years. The great stratified random sample results suggested that, in addition to socio-demographic features, detailed linear trend analysis showed headache features of children with headache have some specific characteristics dependent on age, gender and headache type. This study results can constitute a basis for the future epidemiological based studies.

Stratification of a cityscape using census and land use variables for inventory of building materials

USGS Publications Warehouse

Rosenfield, G.H.; Fitzpatrick-Lins, K.; Johnson, T.L.

1987-01-01

A cityscape (or any landscape) can be stratified into environmental units using multiple variables of information. For the purposes of sampling building materials, census and land use variables were used to identify similar strata. In the Metropolitan Statistical Area of a cityscape, the census tract is the smallest unit for which census data are summarized and digitized boundaries are available. For purposes of this analysis, census data on total population, total number of housing units, and number of singleunit dwellings were aggregated into variables of persons per square kilometer and proportion of housing units in single-unit dwellings. The level 2 categories of the U.S. Geological Survey's land use and land cover data base were aggregated into variables of proportion of residential land with buildings, proportion of nonresidential land with buildings, and proportion of open land. The cityscape was stratified, from these variables, into environmental strata of Urban Central Business District, Urban Livelihood Industrial Commercial, Urban Multi-Family Residential, Urban Single Family Residential, Non-Urban Suburbanizing, and Non-Urban Rural. The New England region was chosen as a region with commonality of building materials, and a procedure developed for trial classification of census tracts into one of the strata. Final stratification was performed by discriminant analysis using the trial classification and prior probabilities as weights. The procedure was applied to several cities, and the results analyzed by correlation analysis from a field sample of building materials. The methodology developed for stratification of a cityscape using multiple variables has application to many other types of environmental studies, including forest inventory, hydrologic unit management, waste disposal, transportation studies, and other urban studies. Multivariate analysis techniques have recently been used for urban stratification in England. ?? 1987 Annals of Regional Science.

Generation of 2D Land Cover Maps for Urban Areas Using Decision Tree Classification

NASA Astrophysics Data System (ADS)

Höhle, J.

2014-09-01

A 2D land cover map can automatically and efficiently be generated from high-resolution multispectral aerial images. First, a digital surface model is produced and each cell of the elevation model is then supplemented with attributes. A decision tree classification is applied to extract map objects like buildings, roads, grassland, trees, hedges, and walls from such an "intelligent" point cloud. The decision tree is derived from training areas which borders are digitized on top of a false-colour orthoimage. The produced 2D land cover map with six classes is then subsequently refined by using image analysis techniques. The proposed methodology is described step by step. The classification, assessment, and refinement is carried out by the open source software "R"; the generation of the dense and accurate digital surface model by the "Match-T DSM" program of the Trimble Company. A practical example of a 2D land cover map generation is carried out. Images of a multispectral medium-format aerial camera covering an urban area in Switzerland are used. The assessment of the produced land cover map is based on class-wise stratified sampling where reference values of samples are determined by means of stereo-observations of false-colour stereopairs. The stratified statistical assessment of the produced land cover map with six classes and based on 91 points per class reveals a high thematic accuracy for classes "building" (99 %, 95 % CI: 95 %-100 %) and "road and parking lot" (90 %, 95 % CI: 83 %-95 %). Some other accuracy measures (overall accuracy, kappa value) and their 95 % confidence intervals are derived as well. The proposed methodology has a high potential for automation and fast processing and may be applied to other scenes and sensors.

Hydrogeology and groundwater quality of the glaciated valleys of Bradford, Tioga, and Potter Counties, Pennsylvania

USGS Publications Warehouse

Williams, John H.; Taylor, Larry E.; Low, Dennis J.

1998-01-01

The most important sources of groundwater in Bradford, Tioga, and Potter Counties are the stratified-drift aquifers. Saturated sand and gravel primarily of outwash origin forms extensive unconfined aquifers in the valleys. Outwash is underlain in most major valleys by silt, clay, and very fine sand of lacustrine origin that comprise extensive confining units. The lacustrine confining units locally exceed 100 feet in thickness. Confined aquifers of ice-contact sand and gravel are buried locally beneath the lacustrine deposits. Bedrock and till are the basal confining units of the stratifies-drift aquifer systems. Recharge to the stratified-drift aquifers if by direct infiltration of precipitation, tributary-stream infiltration, infiltration of unchanneled runoff at the valley walls, and groundwater inflow from the bedrock and till uplands. Valley areas underlain by superficial sand and gravel contribute about 1 million gallons per day per square mile of water from precipitation to the aquifers. Tributary streams provide recharge of nearly 590 gallons per day per foot of stream reach. Water is added at the rate of 1 million gallons per day per square mile of bordering uplands not drained by tributary streams to the stratified-drift aquifers from unchanneled runoff and groundwater inflow. Induced infiltration can be a major source of recharge to well fields completed in unconfined stratified-drift aquifers that are in good hydraulic connection with surface water. The well fields of an industrial site in North Towanda, a public-water supplier at Tioga Point, and the U.S. Fish and Wildlife Service at Asaph accounted for 75 percent of the 10.8 million gallons per day pf groundwater withdrawn by public suppliers and other selected users in 1985. The well fields tap stratified-drift aquifers that are substantially recharged by induced infiltration or tributary-stream infiltration. Specific-capacity data from 95 wells indicate that most wells completed in stratified-drift aquifers have specific capacities an order of magnitude greater than those completed in till and bedrock, Wells completed in unconfined stratified-drift aquifers and in bedrock aquifers have the highest and lowest median specific capacities -- 24 and 0.80 gallons per minute per foot of drawdown, respectively. Wells completed in confined stratified-drift aquifers and in till have median specific capacties of 11 and 0.87 gallons per minute per foot of drawdown, respectively. The results of 223 groundwater-quality analyses indicate two major hydrogeochemical zones: (1) a zone of unrestricted groundwater flow that contains water of the calcium bicarbonate type (this zone is found in almost all of the stratified-drift aquifers, till, and shallow bedrock systems); and (2) a zone of restricted groundwater slow that contains water of the sodium chloride type (this zone is found in the bedrock, and, in some areas, in till and confined stratified-drift aquifers). Samples pumped from wells that penetrate restricted-flow zones have median concentrations of total dissolved solids, dissolved chloride, and dissolved barium of 840 and 350 milligrams per liter, and 2,100 micrograms per liter, respectively. Excessive concentrations of iron and manganese are common in the groundwater of the study area; about 50 percent of the wells sampled contain water that has iron and manganese concentrations that exceed the U.S. Environmental Protection Agency secondary maximum contaminant levels of 300 and 50 micrograms per liter, respectively. Only water in the unconfined stratified-drift aquifers and the Catskill Formation has median concentrations lower than these limits.

Post-stratified estimation: with-in strata and total sample size recommendations

Treesearch

James A. Westfall; Paul L. Patterson; John W. Coulston

2011-01-01

Post-stratification is used to reduce the variance of estimates of the mean. Because the stratification is not fixed in advance, within-strata sample sizes can be quite small. The survey statistics literature provides some guidance on minimum within-strata sample sizes; however, the recommendations and justifications are inconsistent and apply broadly for many...

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.…

Detection and monitoring of invasive exotic plants: a comparison of four sampling methods

Treesearch

Cynthia D. Huebner

2007-01-01

The ability to detect and monitor exotic invasive plants is likely to vary depending on the sampling method employed. Methods with strong qualitative thoroughness for species detection often lack the intensity necessary to monitor vegetation change. Four sampling methods (systematic plot, stratified-random plot, modified Whittaker, and timed meander) in hemlock and red...

Photo stratification improves northwest timber volume estimates.

Treesearch

Colin D. MacLean

1972-01-01

Data from extensive timber inventories of 12 counties in western and central Washington were analyzed to test the relative efficiency of double sampling for stratification as a means of estimating total volume. Photo and field plots, when combined in a stratified sampling design, proved about twice as efficient as simple field sampling. Although some gains were made by...

Relationships among Teachers' Self-Efficacy and Students' Motivation, Atmosphere, and Satisfaction in Physical Education

ERIC Educational Resources Information Center

Pan, Yi-Hsiang

2014-01-01

The purpose of this study was to confirm the relationships among teachers' self-efficacy, and students' learning motivation, learning atmosphere, and learning satisfaction in senior high school physical education (PE). A sample of 462 PE teachers and 2681 students was drawn using stratified random sampling and cluster sampling from high schools in…

Testing the Feasibility of Developmental Asset Measures on College Students to Guide Health Promotion Efforts

ERIC Educational Resources Information Center

Zullig, Keith J.; Ward, Rose Marie; King, Keith A.; Patton, Jon M.; Murray, Karen A.

2009-01-01

The purpose of this investigation was to assess the reliability and validity of eight developmental asset measures among a stratified, random sample (N = 540) of college students to guide health promotion efforts. The sample was randomly split to produce exploratory and confirmatory samples for factor analysis using principal axis factoring and…

Workforce Readiness: A Study of University Students' Fluency with Information Technology

ERIC Educational Resources Information Center

Kaminski, Karen; Switzer, Jamie; Gloeckner, Gene

2009-01-01

This study with data collected from a large sample of freshmen in 2001 and a random stratified sample of seniors in 2005 examined students perceived FITness (fluency with Information Technology). In the fall of 2001 freshmen at a medium sized research-one institution completed a survey and in spring 2005 a random sample of graduating seniors…

Experimental analysis of an oblique turbulent flame front propagating in a stratified flow

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

Galizzi, C.; Escudie, D.

2010-12-15

This paper details the experimental study of a turbulent V-shaped flame expanding in a nonhomogeneous premixed flow. Its aim is to characterize the effects of stratification on turbulent flame characteristics. The setup consists of a stationary V-shaped flame stabilized on a rod and expanding freely in a lean premixed methane-air flow. One of the two oblique fronts interacts with a stratified slice, which has an equivalence ratio close to one and a thickness greater than that of the flame front. Several techniques such as PIV and CH{sup *} chemiluminescence are used to investigate the instantaneous fields, while laser Doppler anemometrymore » and thermocouples are combined with a concentration probe to provide information on the mean fields. First, in order to provide a reference, the homogeneous turbulent case is studied. Next, the stratified turbulent premixed flame is investigated. Results show significant modifications of the whole flame and of the velocity field upstream of the flame front. The analysis of the geometric properties of the stratified flame indicates an increase in flame brush thickness, closely related to the local equivalence ratio. (author)« less

Improvement of Predictive Ability by Uniform Coverage of the Target Genetic Space

PubMed Central

Bustos-Korts, Daniela; Malosetti, Marcos; Chapman, Scott; Biddulph, Ben; van Eeuwijk, Fred

2016-01-01

Genome-enabled prediction provides breeders with the means to increase the number of genotypes that can be evaluated for selection. One of the major challenges in genome-enabled prediction is how to construct a training set of genotypes from a calibration set that represents the target population of genotypes, where the calibration set is composed of a training and validation set. A random sampling protocol of genotypes from the calibration set will lead to low quality coverage of the total genetic space by the training set when the calibration set contains population structure. As a consequence, predictive ability will be affected negatively, because some parts of the genotypic diversity in the target population will be under-represented in the training set, whereas other parts will be over-represented. Therefore, we propose a training set construction method that uniformly samples the genetic space spanned by the target population of genotypes, thereby increasing predictive ability. To evaluate our method, we constructed training sets alongside with the identification of corresponding genomic prediction models for four genotype panels that differed in the amount of population structure they contained (maize Flint, maize Dent, wheat, and rice). Training sets were constructed using uniform sampling, stratified-uniform sampling, stratified sampling and random sampling. We compared these methods with a method that maximizes the generalized coefficient of determination (CD). Several training set sizes were considered. We investigated four genomic prediction models: multi-locus QTL models, GBLUP models, combinations of QTL and GBLUPs, and Reproducing Kernel Hilbert Space (RKHS) models. For the maize and wheat panels, construction of the training set under uniform sampling led to a larger predictive ability than under stratified and random sampling. The results of our methods were similar to those of the CD method. For the rice panel, all training set construction methods led to similar predictive ability, a reflection of the very strong population structure in this panel. PMID:27672112

Physical Activity among Rural Older Adults with Diabetes

ERIC Educational Resources Information Center

Arcury, Thomas A.; Snively, Beverly M.; Bell, Ronny A.; Smith, Shannon L.; Stafford, Jeanette M.; Wetmore-Arkader, Lindsay K.; Quandt, Sara A.

2006-01-01

Purpose: This analysis describes physical activity levels and factors associated with physical activity in an ethnically diverse (African American, Native American, white) sample of rural older adults with diabetes. Method: Data were collected using a population-based, cross-sectional stratified random sample survey of 701 community-dwelling…

In vivo endoscopic OCT imaging of precancer and cancer states of human mucosa

NASA Astrophysics Data System (ADS)

Sergeev, Alexander M.; Gelikonov, V. M.; Gelikonov, G. V.; Feldchtein, Felix I.; Kuranov, R. V.; Gladkova, N. D.; Shakhova, N. M.; Snopova, L. B.; Shakhov, A. V.; Kuznetzova, I. A.; Denisenko, A. N.; Pochinko, V. V.; Chumakov, Yu P.; Streltzova, O. S.

1997-12-01

First results of endoscopic applications of optical coherence tomography for in vivo studies of human mucosa in respiratory, gastrointestinal, urinary and genital tracts are presented. A novel endoscopic OCT (EOCT) system has been created that is based on the integration of a sampling arm of an all-optical-fiber interferometer into standard endoscopic devices using their biopsy channel to transmit low-coherence radiation to investigated tissue. We have studied mucous membranes of esophagus, larynx, stomach, urinary bladder, uterine cervix and body as typical localization for carcinomatous processes. Images of tumor tissues versus healthy tissues have been recorded and analyzed. Violations of well-defined stratified healthy mucosa structure in cancered tissue are distinctly seen by EOCT, thus making this technique promising for early diagnosis of tumors and precise guiding of excisional biopsy.

Integrated endoscopic OCT system and in-vivo images of human internal organs

NASA Astrophysics Data System (ADS)

Sergeev, Alexander M.; Gelikonov, Valentin M.; Gelikonov, Grigory V.; Feldchtein, Felix I.; Kuranov, Roman V.; Gladkova, Natalia D.; Shakhova, Natalia M.; Snopova, Ludmila; Shakhov, Andrei; Kuznetzova, Irina N.; Denisenko, Arkady; Pochinko, Vitaly; Chumakov, Yuri; Almasov, Valentin

1998-04-01

First results of endoscopic applications of optical coherence tomography (OCT) for in vivo studies of human mucosa in respiratory, gastrointestinal, urinary and genital tracts are presented. A novel endoscopic OCT (EOCT) system has been created that is based on the integration of a sampling arm of an all-optical-fiber interferometer into standard endoscopic devices using their biopsy channel to transmit low-coherence radiation to investigated tissue. We have studied mucous membranes of esophagus, larynx, stomach, urinary bladder, uterine cervix and endometrium as typical localization for carcinomatous processes. Images of tumor tissues versus healthy tissues have been recorded and analyzed. Violations of well-defined stratified healthy mucosa structure in cancered tissue is distinctly seen by EOCT, thus making this technique promising for early diagnosis of tumors and precise guiding of excisional biopsy.

At the forefront: evidence of the applicability of using environmental DNA to quantify the abundance of fish populations in natural lentic waters with additional sampling considerations

USGS Publications Warehouse

Klobucar, Stephen L.; Rodgers, Torrey W.; Budy, Phaedra

2017-01-01

Environmental DNA (eDNA) sampling has proven to be a valuable tool for detecting species in aquatic ecosystems. Within this rapidly evolving field, a promising application is the ability to obtain quantitative estimates of relative species abundance based on eDNA concentration rather than traditionally labor-intensive methods. We investigated the relationship between eDNA concentration and Arctic char (Salvelinus alpinus) abundance in five well-studied natural lakes; additionally, we examined the effects of different temporal (e.g., season) and spatial (e.g., depth) scales on eDNA concentration. Concentrations of eDNA were linearly correlated with char population estimates ( = 0.78) and exponentially correlated with char densities ( = 0.96 by area; 0.82 by volume). Across lakes, eDNA concentrations were greater and more homogeneous in the water column during mixis; however, when stratified, eDNA concentrations were greater in the hypolimnion. Overall, our findings demonstrate that eDNA techniques can produce effective estimates of relative fish abundance in natural lakes. These findings can guide future studies to improve and expand eDNA methods while informing research and management using rapid and minimally invasive sampling.

Post-stroke hemiparesis: Does chronicity, etiology, and lesion side are associated with gait pattern?

PubMed

Gama, Gabriela Lopes; Larissa, Coutinho de Lucena; Brasileiro, Ana Carolina de Azevedo Lima; Silva, Emília Márcia Gomes de Souza; Galvão, Élida Rayanne Viana Pinheiro; Maciel, Álvaro Cavalcanti; Lindquist, Ana Raquel Rodrigues

2017-07-01

Studies that evaluate gait rehabilitation programs for individuals with stroke often consider time since stroke of more than six months. In addition, most of these studies do not use lesion etiology or affected cerebral hemisphere as study factors. However, it is unknown whether these factors are associated with post-stroke motor performance after the spontaneous recovery period. To investigate whether time since stroke onset, etiology, and lesion side is associated with spatiotemporal and angular gait parameters of individuals with chronic stroke. Fifty individuals with chronic hemiparesis (20 women) were evaluated. The sample was stratified according to time since stroke (between 6 and 12 months, between 13 and 36 months, and over 36 months), affected cerebral hemisphere (left or right) and lesion etiology (ischemic and hemorrhagic). The participants were evaluated during overground walking at self-selected gait speed, and spatiotemporal and angular gait parameters were calculated. Results Differences between gait speed, stride length, hip flexion, and knee flexion were observed in subgroups stratified based on lesion etiology. Survivors of a hemorrhagic stroke exhibited more severe gait impairment. Subgroups stratified based on time since stroke only showed intergroup differences for stride length, and subgroups stratified based on affected cerebral hemisphere displayed between-group differences for swing time symmetry ratio. In order to recruit a more homogeneous sample, more accurate results were obtained and an appropriate rehabilitation program was offered, researchers and clinicians should consider that gait pattern might be associated with time since stroke, affected cerebral hemisphere and lesion etiology.

A nonparametric method to generate synthetic populations to adjust for complex sampling design features.

PubMed

Dong, Qi; Elliott, Michael R; Raghunathan, Trivellore E

2014-06-01

Outside of the survey sampling literature, samples are often assumed to be generated by a simple random sampling process that produces independent and identically distributed (IID) samples. Many statistical methods are developed largely in this IID world. Application of these methods to data from complex sample surveys without making allowance for the survey design features can lead to erroneous inferences. Hence, much time and effort have been devoted to develop the statistical methods to analyze complex survey data and account for the sample design. This issue is particularly important when generating synthetic populations using finite population Bayesian inference, as is often done in missing data or disclosure risk settings, or when combining data from multiple surveys. By extending previous work in finite population Bayesian bootstrap literature, we propose a method to generate synthetic populations from a posterior predictive distribution in a fashion inverts the complex sampling design features and generates simple random samples from a superpopulation point of view, making adjustment on the complex data so that they can be analyzed as simple random samples. We consider a simulation study with a stratified, clustered unequal-probability of selection sample design, and use the proposed nonparametric method to generate synthetic populations for the 2006 National Health Interview Survey (NHIS), and the Medical Expenditure Panel Survey (MEPS), which are stratified, clustered unequal-probability of selection sample designs.

A nonparametric method to generate synthetic populations to adjust for complex sampling design features

PubMed Central

Dong, Qi; Elliott, Michael R.; Raghunathan, Trivellore E.

2017-01-01

Outside of the survey sampling literature, samples are often assumed to be generated by a simple random sampling process that produces independent and identically distributed (IID) samples. Many statistical methods are developed largely in this IID world. Application of these methods to data from complex sample surveys without making allowance for the survey design features can lead to erroneous inferences. Hence, much time and effort have been devoted to develop the statistical methods to analyze complex survey data and account for the sample design. This issue is particularly important when generating synthetic populations using finite population Bayesian inference, as is often done in missing data or disclosure risk settings, or when combining data from multiple surveys. By extending previous work in finite population Bayesian bootstrap literature, we propose a method to generate synthetic populations from a posterior predictive distribution in a fashion inverts the complex sampling design features and generates simple random samples from a superpopulation point of view, making adjustment on the complex data so that they can be analyzed as simple random samples. We consider a simulation study with a stratified, clustered unequal-probability of selection sample design, and use the proposed nonparametric method to generate synthetic populations for the 2006 National Health Interview Survey (NHIS), and the Medical Expenditure Panel Survey (MEPS), which are stratified, clustered unequal-probability of selection sample designs. PMID:29200608

Training set optimization under population structure in genomic selection

USDA-ARS?s Scientific Manuscript database

The optimization of the training set (TRS) in genomic selection (GS) has received much interest in both animal and plant breeding, because it is critical to the accuracy of the prediction models. In this study, five different TRS sampling algorithms, stratified sampling, mean of the Coefficient of D...

MID-ATLANTIC COASTAL STREAMS STUDY: STATISTICAL DESIGN FOR REGIONAL ASSESSMENT AND LANDSCAPE MODEL DEVELOPMENT

EPA Science Inventory

A network of stream-sampling sites was developed for the Mid-Atlantic Coastal Plain (New Jersey through North Carolina) a collaborative study between the U.S. Environmental Protection Agency and the U.S. Geological Survey. A stratified random sampling with unequal weighting was u...

Perceptions of Learning among Swiss Watch Managers

ERIC Educational Resources Information Center

Tajeddini, Kayhan

2009-01-01

Purpose: This paper aims to explore managers' perceptions of learning within a sample of Swiss watch firms. Design/methodology/approach: A purposeful (judgmental) stratified sampling method was employed, where in-depth interviews with 13 marketing managers and owners were carried out over a three-month period. Meaning units (MUs) were abstracted,…

Employee Engagement and Performance of Lecturers in Nigerian Tertiary Institutions

ERIC Educational Resources Information Center

Agbionu, Uchenna Clementina; Anyalor, Maureen; Nwali, Anthony Chukwuma

2018-01-01

The study investigated employee engagement and performance of lecturers in Nigerian Tertiary Institutions. It employed descriptive and correlation research designs. Stratified random sampling was used to select three tertiary institutions in Nigeria and the sample size of 314 lecturers was obtained through Taro Yamane. Questionnaires were…

MID-ATLANTIC COASTAL STREAMS STUDY: STATISTICAL DESIGN FOR REGIONAL ASSESSMENT AND LANDSCAPE MODEL DEVELOPMENT

EPA Science Inventory

A network of stream-sampling sites was developed for the Mid-Atlantic Coastal Plain (New Jersey through North Carolina) as part of collaborative research between the U.S. Environmental Protection Agency and the U.S. Geological Survey. A stratified random sampling with unequal wei...

Resource Utilisation and Curriculum Implementation in Community Colleges in Kenya

ERIC Educational Resources Information Center

Kigwilu, Peter Changilwa; Akala, Winston Jumba

2017-01-01

The study investigated how Catholic-sponsored community colleges in Nairobi utilise the existing physical facilities and teaching and learning resources for effective implementation of Artisan and Craft curricula. The study adopted a mixed methods research design. Proportional stratified random sampling was used to sample 172 students and 18…

Associations among Adolescent Risk Behaviours and Self-Esteem in Six Domains

ERIC Educational Resources Information Center

Wild, Lauren G.; Flisher, Alan J.; Bhana, Arvin; Lombard, Carl

2004-01-01

Background: This study investigated associations among adolescents' self-esteem in 6 domains (peers, school, family, sports/athletics, body image and global self-worth) and risk behaviours related to substance use, bullying, suicidality and sexuality. Method: A multistage stratified sampling strategy was used to select a representative sample of…

Stratified Sampling Design Based on Data Mining

PubMed Central

Kim, Yeonkook J.; Oh, Yoonhwan; Park, Sunghoon; Cho, Sungzoon

2013-01-01

Objectives To explore classification rules based on data mining methodologies which are to be used in defining strata in stratified sampling of healthcare providers with improved sampling efficiency. Methods We performed k-means clustering to group providers with similar characteristics, then, constructed decision trees on cluster labels to generate stratification rules. We assessed the variance explained by the stratification proposed in this study and by conventional stratification to evaluate the performance of the sampling design. We constructed a study database from health insurance claims data and providers' profile data made available to this study by the Health Insurance Review and Assessment Service of South Korea, and population data from Statistics Korea. From our database, we used the data for single specialty clinics or hospitals in two specialties, general surgery and ophthalmology, for the year 2011 in this study. Results Data mining resulted in five strata in general surgery with two stratification variables, the number of inpatients per specialist and population density of provider location, and five strata in ophthalmology with two stratification variables, the number of inpatients per specialist and number of beds. The percentages of variance in annual changes in the productivity of specialists explained by the stratification in general surgery and ophthalmology were 22% and 8%, respectively, whereas conventional stratification by the type of provider location and number of beds explained 2% and 0.2% of variance, respectively. Conclusions This study demonstrated that data mining methods can be used in designing efficient stratified sampling with variables readily available to the insurer and government; it offers an alternative to the existing stratification method that is widely used in healthcare provider surveys in South Korea. PMID:24175117

Mathematics Skill of Fifteen Years Old Students in Yogyakarta in Solving Problems Like PISA

ERIC Educational Resources Information Center

Wulandari, Nidya Ferry; Jailani

2018-01-01

The aims of this research were to describe mathematics skill of 8th fifteen-year old students in Yogyakarta in solving problem of PISA. The sampling was combination of stratified and cluster random sampling. The sample consisting of 400 students was selected from fifteen schools. The data collection was by tests. The research finding revealed that…

A Pilot Sampling Design for Estimating Outdoor Recreation Site Visits on the National Forests

Treesearch

Stanley J. Zarnoch; S.M. Kocis; H. Ken Cordell; D.B.K. English

2002-01-01

A pilot sampling design is described for estimating site visits to National Forest System lands. The three-stage sampling design consisted of national forest ranger districts, site days within ranger districts, and last-exiting recreation visitors within site days. Stratification was used at both the primary and secondary stages. Ranger districts were stratified based...

The study of combining Latin Hypercube Sampling method and LU decomposition method (LULHS method) for constructing spatial random field

NASA Astrophysics Data System (ADS)

WANG, P. T.

2015-12-01

Groundwater modeling requires to assign hydrogeological properties to every numerical grid. Due to the lack of detailed information and the inherent spatial heterogeneity, geological properties can be treated as random variables. Hydrogeological property is assumed to be a multivariate distribution with spatial correlations. By sampling random numbers from a given statistical distribution and assigning a value to each grid, a random field for modeling can be completed. Therefore, statistics sampling plays an important role in the efficiency of modeling procedure. Latin Hypercube Sampling (LHS) is a stratified random sampling procedure that provides an efficient way to sample variables from their multivariate distributions. This study combines the the stratified random procedure from LHS and the simulation by using LU decomposition to form LULHS. Both conditional and unconditional simulations of LULHS were develpoed. The simulation efficiency and spatial correlation of LULHS are compared to the other three different simulation methods. The results show that for the conditional simulation and unconditional simulation, LULHS method is more efficient in terms of computational effort. Less realizations are required to achieve the required statistical accuracy and spatial correlation.

Genome-wide meta-analyses of stratified depression in Generation Scotland and UK Biobank.

PubMed

Hall, Lynsey S; Adams, Mark J; Arnau-Soler, Aleix; Clarke, Toni-Kim; Howard, David M; Zeng, Yanni; Davies, Gail; Hagenaars, Saskia P; Maria Fernandez-Pujals, Ana; Gibson, Jude; Wigmore, Eleanor M; Boutin, Thibaud S; Hayward, Caroline; Scotland, Generation; Porteous, David J; Deary, Ian J; Thomson, Pippa A; Haley, Chris S; McIntosh, Andrew M

2018-01-10

Few replicable genetic associations for Major Depressive Disorder (MDD) have been identified. Recent studies of MDD have identified common risk variants by using a broader phenotype definition in very large samples, or by reducing phenotypic and ancestral heterogeneity. We sought to ascertain whether it is more informative to maximize the sample size using data from all available cases and controls, or to use a sex or recurrent stratified subset of affected individuals. To test this, we compared heritability estimates, genetic correlation with other traits, variance explained by MDD polygenic score, and variants identified by genome-wide meta-analysis for broad and narrow MDD classifications in two large British cohorts - Generation Scotland and UK Biobank. Genome-wide meta-analysis of MDD in males yielded one genome-wide significant locus on 3p22.3, with three genes in this region (CRTAP, GLB1, and TMPPE) demonstrating a significant association in gene-based tests. Meta-analyzed MDD, recurrent MDD and female MDD yielded equivalent heritability estimates, showed no detectable difference in association with polygenic scores, and were each genetically correlated with six health-correlated traits (neuroticism, depressive symptoms, subjective well-being, MDD, a cross-disorder phenotype and Bipolar Disorder). Whilst stratified GWAS analysis revealed a genome-wide significant locus for male MDD, the lack of independent replication, and the consistent pattern of results in other MDD classifications suggests that phenotypic stratification using recurrence or sex in currently available sample sizes is currently weakly justified. Based upon existing studies and our findings, the strategy of maximizing sample sizes is likely to provide the greater gain.

TWO-DIMENSIONAL MODELING OF AQUIFER REMEDIATION INFLUENCED BY SORPTION NONEQUILIBRIUM AND HYDRAULIC CONDUCTIVITY HETEROGENEITY

EPA Science Inventory

A computational model was developed to simulate aquifer remediation by pump and treat for a confined, perfectly stratified aquifer. plit-operator finite element numerical technique was utilized to incorporate flow field heterogeneity and nonequilibrium sorption into a two-dimensi...

A Fast MHD Code for Gravitationally Stratified Media using Graphical Processing Units: SMAUG

NASA Astrophysics Data System (ADS)

Griffiths, M. K.; Fedun, V.; Erdélyi, R.

2015-03-01

Parallelization techniques have been exploited most successfully by the gaming/graphics industry with the adoption of graphical processing units (GPUs), possessing hundreds of processor cores. The opportunity has been recognized by the computational sciences and engineering communities, who have recently harnessed successfully the numerical performance of GPUs. For example, parallel magnetohydrodynamic (MHD) algorithms are important for numerical modelling of highly inhomogeneous solar, astrophysical and geophysical plasmas. Here, we describe the implementation of SMAUG, the Sheffield Magnetohydrodynamics Algorithm Using GPUs. SMAUG is a 1-3D MHD code capable of modelling magnetized and gravitationally stratified plasma. The objective of this paper is to present the numerical methods and techniques used for porting the code to this novel and highly parallel compute architecture. The methods employed are justified by the performance benchmarks and validation results demonstrating that the code successfully simulates the physics for a range of test scenarios including a full 3D realistic model of wave propagation in the solar atmosphere.

Risk-Stratified Imputation in Survival Analysis

PubMed Central

Kennedy, Richard E.; Adragni, Kofi P.; Tiwari, Hemant K.; Voeks, Jenifer H.; Brott, Thomas G.; Howard, George

2013-01-01

Background Censoring that is dependent on covariates associated with survival can arise in randomized trials due to changes in recruitment and eligibility criteria to minimize withdrawals, potentially leading to biased treatment effect estimates. Imputation approaches have been proposed to address censoring in survival analysis; and while these approaches may provide unbiased estimates of treatment effects, imputation of a large number of outcomes may over- or underestimate the associated variance based on the imputation pool selected. Purpose We propose an improved method, risk-stratified imputation, as an alternative to address withdrawal related to the risk of events in the context of time-to-event analyses. Methods Our algorithm performs imputation from a pool of replacement subjects with similar values of both treatment and covariate(s) of interest, that is, from a risk-stratified sample. This stratification prior to imputation addresses the requirement of time-to-event analysis that censored observations are representative of all other observations in the risk group with similar exposure variables. We compared our risk-stratified imputation to case deletion and bootstrap imputation in a simulated dataset in which the covariate of interest (study withdrawal) was related to treatment. A motivating example from a recent clinical trial is also presented to demonstrate the utility of our method. Results In our simulations, risk-stratified imputation gives estimates of treatment effect comparable to bootstrap and auxiliary variable imputation while avoiding inaccuracies of the latter two in estimating the associated variance. Similar results were obtained in analysis of clinical trial data. Limitations Risk-stratified imputation has little advantage over other imputation methods when covariates of interest are not related to treatment, although its performance is superior when covariates are related to treatment. Risk-stratified imputation is intended for categorical covariates, and may be sensitive to the width of the matching window if continuous covariates are used. Conclusions The use of the risk-stratified imputation should facilitate the analysis of many clinical trials, in which one group has a higher withdrawal rate that is related to treatment. PMID:23818434

Long Term Resource Monitoring Program procedures: fish monitoring

USGS Publications Warehouse

Ratcliff, Eric N.; Glittinger, Eric J.; O'Hara, T. Matt; Ickes, Brian S.

2014-01-01

This manual constitutes the second revision of the U.S. Army Corps of Engineers’ Upper Mississippi River Restoration-Environmental Management Program (UMRR-EMP) Long Term Resource Monitoring Program (LTRMP) element Fish Procedures Manual. The original (1988) manual merged and expanded on ideas and recommendations related to Upper Mississippi River fish sampling presented in several early documents. The first revision to the manual was made in 1995 reflecting important protocol changes, such as the adoption of a stratified random sampling design. The 1995 procedures manual has been an important document through the years and has been cited in many reports and scientific manuscripts. The resulting data collected by the LTRMP fish component represent the largest dataset on fish within the Upper Mississippi River System (UMRS) with more than 44,000 collections of approximately 5.7 million fish. The goal of this revision of the procedures manual is to document changes in LTRMP fish sampling procedures since 1995. Refinements to sampling methods become necessary as monitoring programs mature. Possible refinements are identified through field experiences (e.g., sampling techniques and safety protocols), data analysis (e.g., planned and studied gear efficiencies and reallocations of effort), and technological advances (e.g., electronic data entry). Other changes may be required because of financial necessity (i.e., unplanned effort reductions). This version of the LTRMP fish monitoring manual describes the most current (2014) procedures of the LTRMP fish component.

Consequences of parental corporal punishment on 12-year old children in the Colombo district.

PubMed

de Zoysa, Piyanjali; Newcombe, Peter A; Rajapakse, Lalini

2008-03-01

To study the association between parental corporal punishment and psychological maladjustment in children. Potential mediating variables of this association were explored. The relationship between corporal punishment and physical abuse was also investigated. DESIGN, SETTING AND SAMPLE: The children (N = 1226, 12-year olds) were selected from government schools in the Colombo district, using a stratified random sampling technique. Self-administered instruments, adapted and validated to the Sri Lankan context were used. The experience of parental corporal punishment was shown to be moderately, but significantly, associated with psychological maladjustment in children. This association was enhanced by the child witnessing or experiencing non-parent-to-child violence (eg. domestic, community, teacher and peer violence). The extent of the child's support network, the nature of the parent-child relationship and the child's attitude to corporal punishment did not significantly alter the association between corporal punishment and psychological maladjustment. Corporal punishment was also moderately, but significantly, associated with child physical abuse. Parental corporal punishment is associated with psychological harm for children; this association is further enhanced by other forms of violence in a child's life.

Problem Posing with Realistic Mathematics Education Approach in Geometry Learning

NASA Astrophysics Data System (ADS)

Mahendra, R.; Slamet, I.; Budiyono

2017-09-01

One of the difficulties of students in the learning of geometry is on the subject of plane that requires students to understand the abstract matter. The aim of this research is to determine the effect of Problem Posing learning model with Realistic Mathematics Education Approach in geometry learning. This quasi experimental research was conducted in one of the junior high schools in Karanganyar, Indonesia. The sample was taken using stratified cluster random sampling technique. The results of this research indicate that the model of Problem Posing learning with Realistic Mathematics Education Approach can improve students’ conceptual understanding significantly in geometry learning especially on plane topics. It is because students on the application of Problem Posing with Realistic Mathematics Education Approach are become to be active in constructing their knowledge, proposing, and problem solving in realistic, so it easier for students to understand concepts and solve the problems. Therefore, the model of Problem Posing learning with Realistic Mathematics Education Approach is appropriately applied in mathematics learning especially on geometry material. Furthermore, the impact can improve student achievement.

Hydrogeology and water quality of the stratified-drift aquifer in the Pony Hollow Creek Valley, Tompkins County, New York

USGS Publications Warehouse

Bugliosi, Edward F.; Miller, Todd S.; Reynolds, Richard J.

2014-01-01

The lithology, areal extent, and the water-table configuration in stratified-drift aquifers in the northern part of the Pony Hollow Creek valley in the Town of Newfield, New York, were mapped as part of an ongoing aquifer mapping program in Tompkins County. Surficial geologic and soil maps, well and test-boring records, light detection and ranging (lidar) data, water-level measurements, and passive-seismic surveys were used to map the aquifer geometry, construct geologic sections, and determine the depth to bedrock at selected locations throughout the valley. Additionally, water-quality samples were collected from selected streams and wells to characterize the quality of surface and groundwater in the study area. Sedimentary bedrock underlies the study area and is overlain by unstratified drift (till), stratified drift (glaciolacustrine and glaciofluvial deposits), and recent post glacial alluvium. The major type of unconsolidated, water-yielding material in the study area is stratified drift, which consists of glaciofluvial sand and gravel, and is present in sufficient amounts in most places to form an extensive unconfined aquifer throughout the study area, which is the source of water for most residents, farms, and businesses in the valleys. A map of the water table in the unconfined aquifer was constructed by using (1) measurements made between the mid-1960s through 2010, (2) control on the altitudes of perennial streams at 10-foot contour intervals from lidar data collected by Tompkins County, and (3) water surfaces of ponds and wetlands that are hydraulically connected to the unconfined aquifer. Water-table contours indicate that the direction of groundwater flow within the stratified-drift aquifer is predominantly from the valley walls toward the streams and ponds in the central part of the valley where groundwater then flows southwestward (down valley) toward the confluence with the Cayuta Creek valley. Locally, the direction of groundwater flow is radially away from groundwater mounds that have formed beneath upland tributaries that lose water where they flow on alluvial fans on the margins of the valley. In some places, groundwater that would normally flow toward streams is intercepted by pumping wells. Surface-water samples were collected in 2001 at four sites including Carter, Pony Hollow (two sites), and Chafee Creeks, and from six wells throughout the aquifer. Calcium dominates the cation composition and bicarbonate dominates the anion composition in groundwater and surface-water samples and none of the common inorganic constituents collected exceeded any Federal or State water-quality standards. Groundwater samples were collected from six wells all completed in the unconfined sand and gravel aquifer. Concentrations of calcium and magnesium dominated the ionic composition of the groundwater in all wells sampled. Nitrate, orthophosphate, and trace metals were detected in all groundwater samples, but none were more than U.S. Environmental Protection Agency or New York State Department of Health regulatory limits.

The distribution and stratification of persistent organic pollutants and fatty acids in bottlenose dolphin (Tursiops truncatus) blubber.

PubMed

Ellisor, Debra; McLellan, William; Koopman, Heather; Schwacke, Lori; McFee, Wayne; Kucklick, John

2013-10-01

Blubber has been used for decades to monitor exposure of marine mammals to persistent organic pollutants (POPs). However, little is known about POP variability as a function of blubber depth and across the body of the animal. Remote blubber biopsy sampling (e.g, projectile biopsy) is the most common technique used to acquire samples from free-swimming animals, yet such techniques may result in variable sampling. It is important to understand whether blubber stratification or body location affects POP concentration or the concentration of other important blubber constituents such as fatty acids (FA). To investigate the influence of sampling depth and location on POP concentration, full depth blubber samples were taken from one stranded bottlenose dolphin (Tursiops truncatus) at six different body sites to assess variation in FA distribution and contaminant storage with body location. Three of the samples from different body locations were separated into histologically distinct layers to examine the effect of blubber depth and body location on POPs and FAs. In this individual, both POPs and FAs were heterogeneous with blubber depth and body location. POP concentrations were significantly greater in ventral (average ΣPBDEs 1350 ng/g lipid) and anterior (average ΣPCBs 28,700 ng/g lipid) body locations and greater in the superficial blubber layer (average ΣPCBs 35,500 ng/g lipid) when compared to the deep (8390 ng/g lipid) and middle (23,700 ng/g lipid) layers. Proportionally more dietary FAs were found in dorsal blubber and in middle and deep layers relative to other locations while the reverse was true for biosynthesized FAs. Stratification was further examined in blubber from the same body location in five additional stranded bottlenose dolphins. Although FAs were stratified with blubber depth, lipid-normalized POPs were not significantly different with depth, indicating that POP concentrations can vary in an individual with blubber depth though the direction of POP stratification is not consistent among individuals. Published by Elsevier B.V.

Spatially offset Raman spectroscopy for photon migration investigations in long bone

NASA Astrophysics Data System (ADS)

Sowoidnich, Kay; Churchwell, John H.; Buckley, Kevin; Kerns, Jemma G.; Goodship, Allen E.; Parker, Anthony W.; Matousek, Pavel

2015-07-01

Raman Spectroscopy has become an important technique for assessing the composition of excised sections of bone, and is currently being developed as an in vivo tool for transcutaneous detection of bone disease using spatially offset Raman spectroscopy (SORS). The sampling volume of the Raman technique (and thus the amount of bone material interrogated by SORS) depends on the nature of the photon scattering in the probed tissue. Bone is a complex hierarchical material and to date little is known regarding its diffuse scattering properties which are important for the development and optimization of SORS as a diagnostic tool for characterizing bone disease in vivo. SORS measurements at 830 nm excitation wavelength are carried out on stratified samples to determine the depth from which the Raman signal originates within bone tissue. The measurements are made using a 0.38 mm thin Teflon slice, to give a pronounced and defined spectral signature, inserted in between layers of stacked 0.60 mm thin equine bone slices. Comparing the stack of bone slices with and without underlying bone section below the Teflon slice illustrated that thin sections of bone can lose appreciable number of photons through the unilluminated back surface. The results show that larger SORS offsets lead to progressively larger penetration depth into the sample; different Raman spectral signatures could be retrieved through up to 3.9 mm of overlying bone material with a 7 mm offset. These findings have direct impact on potential diagnostic medical applications; for instance on the detection of bone tumors or areas of infected bone.

Reconnaissance data for selected herbicides, two atrazine metabolities, and nitrate in surface water of the Midwestern United States, 1989-90

USGS Publications Warehouse

Scribner, E.A.; Thurman, E.M.; Goolsby, D.A.; Meyer, M.T.; Mills, M.S.; Pomes, M.L.

1993-01-01

Water-quality data were collected from 147 rivers and streams during 1989-90 to assess selected preemergent herbicides, two atrazine metabolites, and nitrate in 10 Midwestern States. This report includes a description of the sampling design, data collection techniques, laboratory and analytical methods, and a compilation of constituent concentrations and quality-assurance data. All water samples were collected by depth-integrating techniques at three to five locations across the wetted perimeter of each stream. Sites were sampled three times in l989--before application of herbi- cides, during the first major runoff after appli- cation of herbicides, and in the fall during a low-flow period when ground water contributed to most of the streamflow. About 50 sites were selected by a stratified random procedure and resampled for both pre- and post-application herbicide concen- trations in 1990 to verify the 1989 results. Laboratory analyses consisted of both enzyme-linked immunosorbent assay (ELISA) with confirmation by gas chromatography-mass spectrometry (GC/MS). The data are useful in studying herbicide transport, in comparison of the spatial distribution of the post-application concentrations of 11 herbicides and 2 atrazine metabolites (deethylatrazine and deisopropylatrazine) in streams and rivers at a regional scale. It is also useful in examination of annual persistence of herbicides and two metabolites in surface water, and in the assessment of atrazine metabolites as indicators of surface- and ground- water interaction. The reconnaissance data are contained in this report and are also available on computer diskette from the U.S. Geological Survey in Lawrence, Kansas.

Prevalence of bullying in secondary schools in Port Harcourt.

PubMed

Alex-Hart, Balafama Abinye; Okagua, Joyce; Opara, Peace Ibo

2015-11-01

School bullying is a global problem involving a high proportion of students worldwide. However, its prevalence and types in secondary schools in Port Harcourt is not yet known. This study aimed to determine the prevalence and types of bullying in secondary schools in Port Harcourt. A total of 1160 students from six secondary schools in Port Harcourt comprised the sample. This was a cross-sectional school-based study conducted in Port Harcourt in March 2014. Two mixed schools, two all-boys schools, and two all-girls schools were selected using purposive sampling technique. Stratified random sampling technique, by class strata (senior secondary 1, 2 and 3) was used to select 1160 students from the six schools. A 22-item self-administered questionnaire adapted from a previous study was modified and used in this study. The questions covered the prevalence, type of bullying, and socio-demographic data. Data were analyzed using SPSS version 20 (IBM SPSS Incorporated, Chicago, IL, USA). About 82.2% reported being victims of bullying, whereas 64.9% reported being bullies. About 9.7% and 11.8% were neither bullies nor bullied, respectively. Bullying was significantly higher in the all-boys (90.8%) and all-girls (82.9%) schools than in the mixed schools (73.5%), p=0.000. More males were victims (53.4%) and bullies (53.3%) but more females (55.4%) were bully-victims. The most common (57.5%) type of bullying was physical bullying. The rate of bullying was found to be very high in secondary schools in Port Harcourt.

Effects of sampling strategy, detection probability, and independence of counts on the use of point counts

USGS Publications Warehouse

Pendleton, G.W.; Ralph, C. John; Sauer, John R.; Droege, Sam

1995-01-01

Many factors affect the use of point counts for monitoring bird populations, including sampling strategies, variation in detection rates, and independence of sample points. The most commonly used sampling plans are stratified sampling, cluster sampling, and systematic sampling. Each of these might be most useful for different objectives or field situations. Variation in detection probabilities and lack of independence among sample points can bias estimates and measures of precision. All of these factors should be con-sidered when using point count methods.

Community of Inquiry Method and Language Skills Acquisition: Empirical Evidence

ERIC Educational Resources Information Center

Preece, Abdul Shakhour Duncan

2015-01-01

The study investigates the effectiveness of community of inquiry method in preparing students to develop listening and speaking skills in a sample of junior secondary school students in Borno state, Nigeria. A sample of 100 students in standard classes was drawn in one secondary school in Maiduguri metropolis through stratified random sampling…

An Australian Version of the Neighborhood Environment Walkability Scale: Validity Evidence

ERIC Educational Resources Information Center

Cerin, Ester; Leslie, Eva; Owen, Neville; Bauman, Adrian

2008-01-01

This study examined validity evidence for the Australian version of the Neighborhood Environment Walkability Scale (NEWS-AU). A stratified two-stage cluster sampling design was used to recruit 2,650 adults from Adelaide (Australia). The sample was drawn from residential addresses within eight high-walkable and eight low-walkable suburbs matched…

Production ecology of Thuja occidentalis

Treesearch

Philip V. Hofmeyer; Robert S. Seymour; Laura S. Kenefic

2010-01-01

Equations to predict branch and tree leaf area, foliar mass, and stemwood volume were developed from 25 destructively sampled northern white-cedar (Thuja occidentalis L.) trees, a species whose production ecology has not been studied. Resulting models were applied to a large sample of 296 cored trees from 60 sites stratified across a soil gradient...

A Study of the Effects of an Altered Workweek.

ERIC Educational Resources Information Center

Wood Educational Consultants, Edmonton (Alberta).

The purpose of this study was to examine the effects of organizational change arising from alterations in the structuring of the workweek. Data were collected from a stratified random sample of management and nonmanagement personnel employed within the various branches of the Alberta Department of Education. The sample consisted of 132 standard…

Academic Optimism and Organizational Citizenship Behaviour amongst Secondary School Teachers

ERIC Educational Resources Information Center

Makvandi, Abdollah; Naderi, Farah; Makvandi, Behnam; Pasha, Reza; Ehteshamzadeh, Parvin

2018-01-01

The purpose of the study was to investigate the simple and multiple relationships between academic optimism and organizational-citizenship behavior amongst high school teachers in Ramhormoz, Iran. The sample consisted of 250 (125 female and 125 male) teachers, selected by stratified random sampling in 2016- 2017. The measurement tools included…

Change in Coping and Defense Mechanisms across Adulthood: Longitudinal Findings in a European American Sample

ERIC Educational Resources Information Center

Diehl, Manfred; Chui, Helena; Hay, Elizabeth L.; Lumley, Mark A.; Grühn, Daniel; Labouvie-Vief, Gisela

2014-01-01

This study examined longitudinal changes in coping and defense mechanisms in an age- and gender-stratified sample of 392 European American adults. Nonlinear age-related changes were found for the coping mechanisms of sublimation and suppression and the defense mechanisms of intellectualization, doubt, displacement, and regression. The change…

Perceptions of Preservice Teachers regarding the Integration of Information and Communication Technologies in Turkish Education Faculties

ERIC Educational Resources Information Center

Akbulut, Yavuz; Odabasi, H. Ferhan; Kuzu, Abdullah

2011-01-01

This study explored the views of pre-service teachers regarding the indicators of information and communication technologies (ICT) at Turkish education faculties. A cross-sectional survey design was implemented with graduating students enrolled in Turkish education faculties. A combination of stratified random sampling and systematic sampling was…

Relationship between English Learning Motivation Types and Self-Identity Changes among Chinese Students

ERIC Educational Resources Information Center

Yihong, Gao; Yuan, Zhao; Ying, Cheng; Yan, Zhou

2007-01-01

This study investigated the relationship between English learning motivation types and self-identity changes among university students in the People's Republic of China. The sample obtained from a stratified sampling consisted of 2,278 undergraduates from 30 universities in 29 regions. The instrument was a Likert-scale questionnaire which included…

The relationships between sixteen perfluorinated compound concentrations in blood serum and food, and other parameters, in the general population of South Korea with proportionate stratified sampling method.

PubMed

Kim, Hee-Young; Kim, Seung-Kyu; Kang, Dong-Mug; Hwang, Yong-Sik; Oh, Jeong-Eun

2014-02-01

Serum samples were collected from volunteers of various ages and both genders using a proportionate stratified sampling method, to assess the exposure of the general population in Busan, South Korea to perfluorinated compounds (PFCs). 16 PFCs were investigated in serum samples from 306 adults (124 males and 182 females) and one day composite diet samples (breakfast, lunch, and dinner) from 20 of the serum donors, to investigate the relationship between food and serum PFC concentrations. Perfluorooctanoic acid and perfluorooctanesulfonic acid were the dominant PFCs in the serum samples, with mean concentrations of 8.4 and 13 ng/mL, respectively. Perfluorotridecanoic acid was the dominant PFC in the composite food samples, ranging from

The topographic development and areal parametric characterization of a stratified surface polished by mass finishing

NASA Astrophysics Data System (ADS)

Walton, Karl; Blunt, Liam; Fleming, Leigh

2015-09-01

Mass finishing is amongst the most widely used finishing processes in modern manufacturing, in applications from deburring to edge radiusing and polishing. Processing objectives are varied, ranging from the cosmetic to the functionally critical. One such critical application is the hydraulically smooth polishing of aero engine component gas-washed surfaces. In this, and many other applications the drive to improve process control and finish tolerance is ever present. Considering its widespread use mass finishing has seen limited research activity, particularly with respect to surface characterization. The objectives of the current paper are to; characterise the mass finished stratified surface and its development process using areal surface parameters, provide guidance on the optimal parameters and sampling method to characterise this surface type for a given application, and detail the spatial variation in surface topography due to coupon edge shadowing. Blasted and peened square plate coupons in titanium alloy are wet (vibro) mass finished iteratively with increasing duration. Measurement fields are precisely relocated between iterations by fixturing and an image superimposition alignment technique. Surface topography development is detailed with ‘log of process duration’ plots of the ‘areal parameters for scale-limited stratified functional surfaces’, (the Sk family). Characteristic features of the Smr2 plot are seen to map out the processing of peak, core and dale regions in turn. These surface process regions also become apparent in the ‘log of process duration’ plot for Sq, where lower core and dale regions are well modelled by logarithmic functions. Surface finish (Ra or Sa) with mass finishing duration is currently predicted with an exponential model. This model is shown to be limited for the current surface type at a critical range of surface finishes. Statistical analysis provides a group of areal parameters including; Vvc, Sq, and Sdq, showing optimal discrimination for a specific range of surface finish outcomes. As a consequence of edge shadowing surface segregation is suggested for characterization purposes.

Prevalence of allergic rhinitis among elementary and middle school students in Changsha city and its impact on quality of life.

PubMed

Song, Y; Wang, M; Xie, J; Li, W; Zhang, X; Wang, T; Tan, G

2015-11-01

To investigate the prevalence of allergic rhinitis among elementary and middle school students and examine its impact on their quality of life. Stratified sampling and cluster sampling surveys were performed among 10-17-year-old students in Changsha city from June 2011 to April 2012. In the stratified sampling survey, the self-reported allergic rhinitis rate was 42.5 per cent. Further examination demonstrated that the average prevalence of allergic rhinitis was 19.4 per cent. The cluster sampling survey demonstrated that 214 of 814 students appeared to be atopic (26.3 per cent). The prevalence of allergic rhinitis and asthma was 17.2 and 2.1 per cent, respectively. In total, 71 atopic individuals (8.7 per cent) were without any symptoms of allergic disease. Further analysis showed that allergic rhinitis influenced the students' sleep, emotions and memory (p < 0.001). The prevalence of allergic rhinitis was 15.8 -19.4 per cent, showing an increase with age. Allergic rhinitis affected students' sleep, emotions and memory.

Numerical and Experimental Investigation of Stratified Gas-Liquid Two-Phase Flow in Horizontal Circular Pipes

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

Faccini, J.L.H.; Sampaio, P.A.B. de; Su, J.

This paper reports numerical and experimental investigation of stratified gas-liquid two-phase flow in horizontal circular pipes. The Reynolds averaged Navier Stokes equations (RANS) with the k-{omega} model for a fully developed stratified gas-liquid two-phase flow are solved by using the finite element method. A smooth and horizontal interface surface is assumed without considering the interfacial waves. The continuity of the shear stress across the interface is enforced with the continuity of the velocity being automatically satisfied by the variational formulation. For each given interface position and longitudinal pressure gradient, an inner iteration loop runs to solve the nonlinear equations. Themore » Newton-Raphson scheme is used to solve the transcendental equations by an outer iteration to determine the interface position and pressure gradient for a given pair of volumetric flow rates. The interface position in a 51.2 mm ID circular pipe was measured experimentally by the ultrasonic pulse-echo technique. The numerical results were also compared with experimental results in a 21 mm ID circular pipe reported by Masala [1]. The good agreement between the numerical and experimental results indicates that the k-{omega} model can be applied for the numerical simulation of stratified gas-liquid two-phase flow. (authors)« less

TWO-DIMENSIONAL MODELING OF AQUIFER REMEDIATION INFLUENCED BY SORPTION NONEQUILIBRIUM AND HYDRAULIC CONDUCTIVITY HETEROGENEITY

EPA Science Inventory

A computational model was developed to simulate aquifer remediation by pump and treat for a confined, perfectly stratified aquifer. A split-operator finite element numerical technique was utilized to incorporate flow field heterogeneity and nonequilibrium sorption into a two-dime...

Middle School Students' Perceptions of Social Dimensions as Influencers of Academic Engagement

ERIC Educational Resources Information Center

Bishop, Penny A.; Pflaum, Susanna W.

2005-01-01

This qualitative study investigates rural middle school students' perceptions of academic engagement. Participant-produced drawings (Kearney & Hyle, 2003), integrated with a series of semi-structured interviews (Patton, 2002), served as the primary data collection techniques. Twenty middle school students participated, stratified for socioeconomic…

Preliminary appraisal of the effects of land use on water quality in stratified-drift aquifers in Connecticut

USGS Publications Warehouse

Grady, S.J.; Weaver, M.F.

1988-01-01

The stratified-drift aquifers that underlie 7.9 sq mi of the Potatuck and 12.7 sq mi of the Pomperaug River valley, CT, consist primarily of sand and gravel deposits up to 150 ft thick. Average horizontal hydraulic conductivity of the stratified drift ranges from 20 to 170 ft/day, and groundwater flows through the aquifers at an average rate of 2 to 3 ft/day. Land use in the study areas is changing from primarily undeveloped or agricultural lands to expanding residential, commercial, and light-industrial uses. Water quality data for 1923-82, that include 127 partial chemical analyses of groundwater samples from 38 wells in the two aquifers, were augmented by sampling during 1985 from 21 new stainless-steel wells for selected major inorganic constituents, trace elements, and organic chemicals. Nonparametric statistical procedures were used to compare the water quality data from four land use areas, for the two sampling periods, and between the two aquifers. Human activities associated with agricultural, residential, and industrial/commercial land uses have affected the quality of water in the stratified-drift aquifers underlying these land use areas. Statistical comparisons of water quality data between land use areas show significant differences, with the apparent relations between land use and groundwater being: (1) Median concentrations of most groundwater constituents are smallest in undeveloped areas; (2) Groundwater in agricultural areas has the largest median sulfate and total ammonia plus organic nitrogen concentrations. Agricultural areas are also characterized by groundwater with significantly greater median specific conductance, noncarbonate hardness, carbon dioxide, and magnesium concentrations relative to undeveloped areas; (3) Median concentrations of most major inorganic constituents, excluding potassium, sulfate, and total ammonia plus organic nitrogen, are greater in groundwater in residential areas than in undeveloped and agricultural areas. (4) Groundwater in industrial/commercial areas has the greatest median specific conductance, pH, carbon dioxide, calcium, magnesium, chloride bicarbonate, dissolved solids, boron, and strontium concentrations. (Author 's abstract)

Modeling abundance using multinomial N-mixture models

USGS Publications Warehouse

Royle, Andy

2016-01-01

Multinomial N-mixture models are a generalization of the binomial N-mixture models described in Chapter 6 to allow for more complex and informative sampling protocols beyond simple counts. Many commonly used protocols such as multiple observer sampling, removal sampling, and capture-recapture produce a multivariate count frequency that has a multinomial distribution and for which multinomial N-mixture models can be developed. Such protocols typically result in more precise estimates than binomial mixture models because they provide direct information about parameters of the observation process. We demonstrate the analysis of these models in BUGS using several distinct formulations that afford great flexibility in the types of models that can be developed, and we demonstrate likelihood analysis using the unmarked package. Spatially stratified capture-recapture models are one class of models that fall into the multinomial N-mixture framework, and we discuss analysis of stratified versions of classical models such as model Mb, Mh and other classes of models that are only possible to describe within the multinomial N-mixture framework.

Evaluation of SLAR and thematic mapper MSS data for forest cover mapping using computer-aided analysis techniques

NASA Technical Reports Server (NTRS)

Hoffer, R. M. (Principal Investigator); Knowlton, D. J.; Dean, M. E.

1981-01-01

A set of training statistics for the 30 meter resolution simulated thematic mapper MSS data was generated based on land use/land cover classes. In addition to this supervised data set, a nonsupervised multicluster block of training statistics is being defined in order to compare the classification results and evaluate the effect of the different training selection methods on classification performance. Two test data sets, defined using a stratified sampling procedure incorporating a grid system with dimensions of 50 lines by 50 columns, and another set based on an analyst supervised set of test fields were used to evaluate the classifications of the TMS data. The supervised training data set generated training statistics, and a per point Gaussian maximum likelihood classification of the 1979 TMS data was obtained. The August 1980 MSS data was radiometrically adjusted. The SAR data was redigitized and the SAR imagery was qualitatively analyzed.

The association of urbanisation with the prevalence of dental caries among schoolchildren in Nigeria new capital territory.

PubMed

el-Nadeef, M A; Adegbembo, A O; Honkala, E

1998-02-01

The aim of this study was to examine the association of urbanisation and social class with dental caries. A multi-stage stratified cluster sampling technique was used to select schoolchildren (n = 915). Clinical examination was carried out in daylight according to WHO criteria. The distribution of the subjects between strata was: 315 (urban); 303 (semi-urban) and 297 (rural). The mean age of subjects in each strata was 11.4 years. The mean number of decayed teeth (DT) in the respective strata were 27 per cent; 24 per cent; and 12 per cent. Urban children and semi-urban had higher risk for caries than their rural reference group. Urbanisation had no significant effect on the caries prevalence when social class was controlled except among subjects from the low social class in semi-urban areas. The development of satellite towns around big cities do have implications for planning oral health services.

An examination of presenteeism measures: the association of three scoring methods with health, work life, and consumer activation.

PubMed

Terry, Paul E; Xi, Min

2010-12-01

The objective of this study was to assess the validity of 3 scoring techniques for presenteeism measures by exploring their relationship with patient activation, health, job satisfaction, and socioeconomic characteristics. The sample consisted of 631 employees from 2 predominantly white-collar employee groups in the northern Midwest. Employees completed the World Health Organization's Health and Work Performance Questionnaire, a wellness profile, and the Patient Activation Measure. Absolute measures reflect self-rated performance, while relative and stratified measures compare self-rated performance to that of co-workers. Multivariate analyses were used to validate scoring measures. All measures of presenteeism were positively correlated with being nonwhite, income, and smoking. The significance of age, employment, mental health, and patient activation depends on how presenteeism is defined. Practitioners must carefully consider which scoring method best addresses their program goals and objectives. Clearer measurement guidelines are needed.

Dietary habits and physical activity levels in Jordanian adolescents attending private versus public schools.

PubMed

Tayyem, R F; Al-Hazzaa, H M; Abu-Mweis, S S; Bawadi, H A; Hammad, S S; Musaiger, A O

2014-07-08

The present study examined differences in dietary habits and physical activity levels between students attending private and public high schools in Jordan. A total of 386 secondary-school males and 349 females aged 14-18 years were randomly recruited using a multistage, stratified, cluster sampling technique. Dietary habits and physical activity level were self-reported in a validated questionnaire. The prevalence of obesity was significantly higher among adolescents in private (26.0%) than in public schools (16.7%). The frequency of breakfast intake was significantly higher among adolescents in private schools, whereas French fries and sweets intake was significantly higher in public schools. Television viewing showed a significant interaction with school type by sex. A higher rate of inactivity was found among students attending private schools. Despite a slightly better overall dietary profile for students in private schools, they had a higher rate of overweight and obesity compared with those in public schools.

The art and science of weed mapping

USGS Publications Warehouse

Barnett, David T.; Stohlgren, Thomas J.; Jarnevich, Catherine S.; Chong, Geneva W.; Ericson, Jenny A.; Davern, Tracy R.; Simonson, Sara E.

2007-01-01

Land managers need cost-effective and informative tools for non-native plant species management. Many local, state, and federal agencies adopted mapping systems designed to collect comparable data for the early detection and monitoring of non-native species. We compared mapping information to statistically rigorous, plot-based methods to better understand the benefits and compatibility of the two techniques. Mapping non-native species locations provided a species list, associated species distributions, and infested area for subjectively selected survey sites. The value of this information may be compromised by crude estimates of cover and incomplete or biased estimations of species distributions. Incorporating plot-based assessments guided by a stratified-random sample design provided a less biased description of non-native species distributions and increased the comparability of data over time and across regions for the inventory, monitoring, and management of non-native and native plant species.

Precompetitive achievement goals, stress appraisals, emotions, and coping among athletes.

PubMed

Nicholls, Adam R; Perry, John L; Calmeiro, Luis

2014-10-01

Grounded in Lazarus's (1991, 1999, 2000) cognitive-motivational-relational theory of emotions, we tested a model of achievement goals, stress appraisals, emotions, and coping. We predicted that precompetitive achievement goals would be associated with appraisals, appraisals with emotions, and emotions with coping in our model. The mediating effects of emotions among the overall sample of 827 athletes and two stratified random subsamples were also explored. The results of this study support our proposed model in the overall sample and the stratified subsamples. Further, emotion mediated the relationship between appraisal and coping. Mediation analyses revealed that there were indirect effects of pleasant and unpleasant emotions, which indicates the importance of examining multiple emotions to reveal a more accurate representation of the overall stress process. Our findings indicate that both appraisals and emotions are just as important in shaping coping.

Development of WAIS-III General Ability Index Minus WMS-III memory discrepancy scores.

PubMed

Lange, Rael T; Chelune, Gordon J; Tulsky, David S

2006-09-01

Analysis of the discrepancy between intellectual functioning and memory ability has received some support as a useful means for evaluating memory impairment. In recent additions to Wechlser scale interpretation, the WAIS-III General Ability Index (GAI) and the WMS-III Delayed Memory Index (DMI) were developed. The purpose of this investigation is to develop base rate data for GAI-IMI, GAI-GMI, and GAI-DMI discrepancy scores using data from the WAIS-III/WMS-III standardization sample (weighted N = 1250). Base rate tables were developed using the predicted-difference method and two simple-difference methods (i.e., stratified and non-stratified). These tables provide valuable data for clinical reference purposes to determine the frequency of GAI-IMI, GAI-GMI, and GAI-DMI discrepancy scores in the WAIS-III/WMS-III standardization sample.

Implications of sampling design and sample size for national carbon accounting systems.

PubMed

Köhl, Michael; Lister, Andrew; Scott, Charles T; Baldauf, Thomas; Plugge, Daniel

2011-11-08

Countries willing to adopt a REDD regime need to establish a national Measurement, Reporting and Verification (MRV) system that provides information on forest carbon stocks and carbon stock changes. Due to the extensive areas covered by forests the information is generally obtained by sample based surveys. Most operational sampling approaches utilize a combination of earth-observation data and in-situ field assessments as data sources. We compared the cost-efficiency of four different sampling design alternatives (simple random sampling, regression estimators, stratified sampling, 2-phase sampling with regression estimators) that have been proposed in the scope of REDD. Three of the design alternatives provide for a combination of in-situ and earth-observation data. Under different settings of remote sensing coverage, cost per field plot, cost of remote sensing imagery, correlation between attributes quantified in remote sensing and field data, as well as population variability and the percent standard error over total survey cost was calculated. The cost-efficiency of forest carbon stock assessments is driven by the sampling design chosen. Our results indicate that the cost of remote sensing imagery is decisive for the cost-efficiency of a sampling design. The variability of the sample population impairs cost-efficiency, but does not reverse the pattern of cost-efficiency of the individual design alternatives. Our results clearly indicate that it is important to consider cost-efficiency in the development of forest carbon stock assessments and the selection of remote sensing techniques. The development of MRV-systems for REDD need to be based on a sound optimization process that compares different data sources and sampling designs with respect to their cost-efficiency. This helps to reduce the uncertainties related with the quantification of carbon stocks and to increase the financial benefits from adopting a REDD regime.

Classification of drugs with different risk profiles.

PubMed

Saedder, Eva Aggerholm; Brock, Birgitte; Nielsen, Lars Peter; Bonnerup, Dorthe Krogsgaard; Lisby, Marianne

2015-08-01

A risk stratification approach is needed to identify patients at high risk of medication errors and a resulting high need of medication review. The aim of this study was to perform risk stratification (distinguishing between low-risk, medium-risk and high-risk drugs) for drugs found to cause serious adverse reactions due to medication errors. The study employed a modified Delphi technique. Drugs from a systematic literature search were included into two rounds of a Delphi process. A panel of experts was asked to evaluate each identified drug's potential for harm and for clinically relevant drug-drug interactions on a scale from 1 (low risk) to 9 (high risk). A total of 36 experts were appointed to serve on the panel. Consensus was reached for 29/57 (51%) drugs or drug classes that cause harm, and for 32/57 (56%) of the drugs or drug classes that cause interactions. For the remaining drugs, a decision was made based on the median score. Two lists, one stating the drugs' potential for causing harm and the other stating clinically relevant drug-drug interactions, were stratified into low-risk, medium-risk and high-risk drugs. Based on a modified Delphi technique, we created two lists of drugs stratified into a low-risk, a medium-risk and a high-risk group of clinically relevant interactions or risk of harm to patients. The lists could be incorporated into a risk-scoring tool that stratifies the performance of medication reviews according to patients' risk of experiencing adverse reactions. none. not relevant.

A Model-Based Approach to Inventory Stratification

Treesearch

Ronald E. McRoberts

2006-01-01

Forest inventory programs report estimates of forest variables for areas of interest ranging in size from municipalities to counties to States and Provinces. Classified satellite imagery has been shown to be an effective source of ancillary data that, when used with stratified estimation techniques, contributes to increased precision with little corresponding increase...

Statistical Strategy for Inventorying and Monitoring the Ecosystem Resources of the State of Jalisco at Multiple Scales and Resolution Levels

Treesearch

Robin M. Reich; Hans T. Schreuder

2006-01-01

The sampling strategy involving both statistical and in-place inventory information is presented for the natural resources project of the Green Belt area (Centuron Verde) in the Mexican state of Jalisco. The sampling designs used were a grid based ground sample of a 90x90 m plot and a two-stage stratified sample of 30 x 30 m plots. The data collected were used to...

Estimation of infection prevalence and sensitivity in a stratified two-stage sampling design employing highly specific diagnostic tests when there is no gold standard.

PubMed

Miller, Ezer; Huppert, Amit; Novikov, Ilya; Warburg, Alon; Hailu, Asrat; Abbasi, Ibrahim; Freedman, Laurence S

2015-11-10

In this work, we describe a two-stage sampling design to estimate the infection prevalence in a population. In the first stage, an imperfect diagnostic test was performed on a random sample of the population. In the second stage, a different imperfect test was performed in a stratified random sample of the first sample. To estimate infection prevalence, we assumed conditional independence between the diagnostic tests and develop method of moments estimators based on expectations of the proportions of people with positive and negative results on both tests that are functions of the tests' sensitivity, specificity, and the infection prevalence. A closed-form solution of the estimating equations was obtained assuming a specificity of 100% for both tests. We applied our method to estimate the infection prevalence of visceral leishmaniasis according to two quantitative polymerase chain reaction tests performed on blood samples taken from 4756 patients in northern Ethiopia. The sensitivities of the tests were also estimated, as well as the standard errors of all estimates, using a parametric bootstrap. We also examined the impact of departures from our assumptions of 100% specificity and conditional independence on the estimated prevalence. Copyright © 2015 John Wiley & Sons, Ltd.

Hierarchical model analysis of the Atlantic Flyway Breeding Waterfowl Survey

USGS Publications Warehouse

Sauer, John R.; Zimmerman, Guthrie S.; Klimstra, Jon D.; Link, William A.

2014-01-01

We used log-linear hierarchical models to analyze data from the Atlantic Flyway Breeding Waterfowl Survey. The survey has been conducted by state biologists each year since 1989 in the northeastern United States from Virginia north to New Hampshire and Vermont. Although yearly population estimates from the survey are used by the United States Fish and Wildlife Service for estimating regional waterfowl population status for mallards (Anas platyrhynchos), black ducks (Anas rubripes), wood ducks (Aix sponsa), and Canada geese (Branta canadensis), they are not routinely adjusted to control for time of day effects and other survey design issues. The hierarchical model analysis permits estimation of year effects and population change while accommodating the repeated sampling of plots and controlling for time of day effects in counting. We compared population estimates from the current stratified random sample analysis to population estimates from hierarchical models with alternative model structures that describe year to year changes as random year effects, a trend with random year effects, or year effects modeled as 1-year differences. Patterns of population change from the hierarchical model results generally were similar to the patterns described by stratified random sample estimates, but significant visibility differences occurred between twilight to midday counts in all species. Controlling for the effects of time of day resulted in larger population estimates for all species in the hierarchical model analysis relative to the stratified random sample analysis. The hierarchical models also provided a convenient means of estimating population trend as derived statistics from the analysis. We detected significant declines in mallard and American black ducks and significant increases in wood ducks and Canada geese, a trend that had not been significant for 3 of these 4 species in the prior analysis. We recommend using hierarchical models for analysis of the Atlantic Flyway Breeding Waterfowl Survey.

Information content of household-stratified epidemics.

PubMed

Kinyanjui, T M; Pellis, L; House, T

2016-09-01

Household structure is a key driver of many infectious diseases, as well as a natural target for interventions such as vaccination programs. Many theoretical and conceptual advances on household-stratified epidemic models are relatively recent, but have successfully managed to increase the applicability of such models to practical problems. To be of maximum realism and hence benefit, they require parameterisation from epidemiological data, and while household-stratified final size data has been the traditional source, increasingly time-series infection data from households are becoming available. This paper is concerned with the design of studies aimed at collecting time-series epidemic data in order to maximize the amount of information available to calibrate household models. A design decision involves a trade-off between the number of households to enrol and the sampling frequency. Two commonly used epidemiological study designs are considered: cross-sectional, where different households are sampled at every time point, and cohort, where the same households are followed over the course of the study period. The search for an optimal design uses Bayesian computationally intensive methods to explore the joint parameter-design space combined with the Shannon entropy of the posteriors to estimate the amount of information in each design. For the cross-sectional design, the amount of information increases with the sampling intensity, i.e., the designs with the highest number of time points have the most information. On the other hand, the cohort design often exhibits a trade-off between the number of households sampled and the intensity of follow-up. Our results broadly support the choices made in existing epidemiological data collection studies. Prospective problem-specific use of our computational methods can bring significant benefits in guiding future study designs. Copyright © 2016 The Authors. Published by Elsevier B.V. All rights reserved.

One size does not fit all: an examination of low birthweight disparities among a diverse set of racial/ethnic groups.

PubMed

Johnelle Sparks, P

2009-11-01

To examine disparities in low birthweight using a diverse set of racial/ethnic categories and a nationally representative sample. This research explored the degree to which sociodemographic characteristics, health care access, maternal health status, and health behaviors influence birthweight disparities among seven racial/ethnic groups. Binary logistic regression models were estimated using a nationally representative sample of singleton, normal for gestational age births from 2001 using the ECLS-B, which has an approximate sample size of 7,800 infants. The multiple variable models examine disparities in low birthweight (LBW) for seven racial/ethnic groups, including non-Hispanic white, non-Hispanic black, U.S.-born Mexican-origin Hispanic, foreign-born Mexican-origin Hispanic, other Hispanic, Native American, and Asian mothers. Race-stratified logistic regression models were also examined. In the full sample models, only non-Hispanic black mothers have a LBW disadvantage compared to non-Hispanic white mothers. Maternal WIC usage was protective against LBW in the full models. No prenatal care and adequate plus prenatal care increase the odds of LBW. In the race-stratified models, prenatal care adequacy and high maternal health risks are the only variables that influence LBW for all racial/ethnic groups. The race-stratified models highlight the different mechanism important across the racial/ethnic groups in determining LBW. Differences in the distribution of maternal sociodemographic, health care access, health status, and behavior characteristics by race/ethnicity demonstrate that a single empirical framework may distort associations with LBW for certain racial and ethnic groups. More attention must be given to the specific mechanisms linking maternal risk factors to poor birth outcomes for specific racial/ethnic groups.

Assessing accuracy of point fire intervals across landscapes with simulation modelling

Treesearch

Russell A. Parsons; Emily K. Heyerdahl; Robert E. Keane; Brigitte Dorner; Joseph Fall

2007-01-01

We assessed accuracy in point fire intervals using a simulation model that sampled four spatially explicit simulated fire histories. These histories varied in fire frequency and size and were simulated on a flat landscape with two forest types (dry versus mesic). We used three sampling designs (random, systematic grids, and stratified). We assessed the sensitivity of...

The Relationship between Happiness, Subjective Well-Being, Creativity and Job Performance of Primary School Teachers in Ramhormoz City

ERIC Educational Resources Information Center

Jalali, Zohreh; Heidari, Alireza

2016-01-01

The research aimed to investigate the relationship between happiness, subjective well-being, creativity and job performance of primary school teachers in Ramhormoz City. Hence, a sample of 330 individuals was selected through random stratified sampling. The research tools included Oxford Happiness Inventory, Subjective Well-being Scale by Keyes…

Sexual Abuse among Female High School Students in Istanbul, Turkey

ERIC Educational Resources Information Center

Alikasifoglu, Mujgan; Erginoz, Ethem; Ercan, Oya; Albayrak-Kaymak, Deniz; Uysal, Omer; Ilter, Ozdemir

2006-01-01

Objective: The objective of the study was to determine the prevalence of sexual abuse in female adolescents in Istanbul, Turkey from data collected as part of a school-based population study on health and health behaviors. Method: A stratified cluster sampling procedure was used for this cross-sectional study. The study sample included 1,955…

Inclusive Education in Spain: How Do Skills, Resources, and Supports Affect Regular Education Teachers' Perceptions of Inclusion?

ERIC Educational Resources Information Center

Chiner, Esther; Cardona, Maria Cristina

2013-01-01

This study examined regular education teachers' perceptions of inclusion in elementary and secondary schools in Spain and how these perceptions may differ depending on teaching experience, skills, and the availability of resources and supports. Stratified random sampling procedures were used to draw a representative sample of 336 general education…

Nonmanufacturing Businesses. U.S. Metric Study Interim Report.

ERIC Educational Resources Information Center

Cornog, June R.; Bunten, Elaine D.

In this fifth interim report on the feasibility of a United States changeover to a metric system stems from the U.S. Metric Study, a primary stratified sample of 2,828 nonmanufacturing firms was randomly selected from 28,184 businesses taken from Social Security files, a secondary sample of 2,258 firms was randomly selected for replacement…

Academic Optimism, Hope and Zest for Work as Predictors of Teacher Self-Efficacy and Perceived Success

ERIC Educational Resources Information Center

Sezgin, Ferudun; Erdogan, Onur

2015-01-01

This study explores the predictive influence of primary school teachers' academic optimism, hope and zest for work on perceptions of their self-efficacy and success. A total of 600 teachers were selected through stratified sampling from 27 primary schools in central districts of Ankara, Turkey, to form the research sample. Intervariable…

Farmer Perceptions of Soil and Water Conservation Issues: Implications to Agricultural and Extension Education.

ERIC Educational Resources Information Center

Bruening, Thomas H.; Martin, Robert A.

A sample of 731 farmers was surveyed to identify perceptions regarding selected soil and water conservation practices. The sample was stratified and proportioned by conservation district to have a representative group of respondents across Iowa. Items on the mailed questionnaire were designed to assess perceptions regarding issues in soil and…

Employment Opportunities in Applied Biological and Agricultural Occupations in the Metropolitan Area of Chicago.

ERIC Educational Resources Information Center

Thomas, Hollie B.; Neavill, Arthur

Based on questionnaire data collected from a sample of employers, this phase of a larger research project ascertained employment opportunities in the area of applied biological and agricultural occupations in the metropolitan area of Chicago. Specific fields of business surveyed by stratified random sample were animal care, animal health care,…

Academic Research Equipment in Selected Science Engineering Fields: 1982-83 to 1985-86.

ERIC Educational Resources Information Center

Burgdorf, Kenneth; Chaney, Bradford

This report presents information for identification of the national trends in the amount, age, loss, condition, and perceived adequacy of academic research equipment in selected science and engineering fields. The data were obtained from a stratified probability sample of 55 colleges and universities and from a separately selected sample of 24…

Society Membership Survey: 1986 Salaries.

ERIC Educational Resources Information Center

Skelton, W. Keith; And Others

The fourth in a series of reports produced by the Education and Employment Statistics division of the American Insititute of Physics (AIP) is presented. Data are based on a stratified random sample survey of one-sixth of the U.S. and Canadian membership of the AIP member societies. In the spring of 1986, every individual in the sample received a…

Teaching Aptitude of Student Teachers and their Academic Achievements at Graduate Level

ERIC Educational Resources Information Center

Sajan, K. S.

2010-01-01

The present investigation aims at studying teaching aptitude of student teachers with respect to their gender and academic achievement at graduate level examination. The sample for this study is selected by stratified random sampling from the Teacher Education institutions of Malabar area of Kerala. Teaching Aptitude Test Battery (T A T B)…

Problems of Female School Teachers in District Kulgam (J&K)

ERIC Educational Resources Information Center

Rashid, Ruhee; Maharashi, Santosh Kumar

2015-01-01

The purpose of this study is to find the problems of employed female school teachers in district Kulgam. Sample of 100 employed women are selected from different education institutions as 20 Rehaber e Taleem (ReT) female teachers, 40 female teachers, 20 female masters and 20 female lecturers using stratified random sampling. In this study we use…

The Importance of Motivational Appeals to Cooperative Extension Agricultural Clientele. Summary of Research.

ERIC Educational Resources Information Center

Wilson, Gary; Newcomb, L. H.

A study was conducted to determine the relationship of certain motivational appeals to the extent of participation of extension clientele, as perceived by these clientele. A stratified random sample of thirty counties from the ten extension supervisory areas of Ohio was used for the study. This sample provided for 395 adult agricultural clientele…

Evaluation of hydraulic conductivities calculated from multi-port permeameter measurements

USGS Publications Warehouse

Wolf, Steven H.; Celia, Michael A.; Hess, Kathryn M.

1991-01-01

A multiport permeameter was developed for use in estimating hydraulic conductivity over intact sections of aquifer core using the core liner as the permeameter body. Six cores obtained from one borehole through the upper 9 m of a stratified glacial-outwash aquifer were used to evaluate the reliability of the permeameter. Radiographs of the cores were used to assess core integrity and to locate 5- to 10-cm sections of similar grain size for estimation of hydraulic conductivity. After extensive testing of the permeameter, hydraulic conductivities were determined for 83 sections of the six cores. Other measurement techniques included permeameter measurements on repacked sections of core, estimates based on grain-size analyses, and estimates based on borehole flowmeter measurements. Permeameter measurements of 33 sections of core that had been extruded, homogenized, and repacked did not differ significantly from the original measurements. Hydraulic conductivities estimated from grain-size distributions were slightly higher than those calculated from permeameter measurements; the significance of the difference depended on the estimating equation used. Hydraulic conductivities calculated from field measurements, using a borehole flowmeter in the borehole from which the cores were extracted, were significantly higher than those calculated from laboratory measurements and more closely agreed with independent estimates of hydraulic conductivity based on tracer movement near the borehole. This indicates that hydraulic conductivities based on laboratory measurements of core samples may underestimate actual field hydraulic conductivities in this type of stratified glacial-outwash aquifer.

Analysis of regional-scale vegetation dynamics of Mexico using stratified AVHRR NDVI data. [Normalized Difference Vegetaion Index

NASA Technical Reports Server (NTRS)

Turcotte, Kevin M.; Kramber, William J.; Venugopal, Gopalan; Lulla, Kamlesh

1989-01-01

Previous studies have shown that a good relationship exists between AVHRR Normalized Difference Vegetation Index (NDVI) measurements, and both regional-scale patterns of vegetation seasonality and productivity. Most of these studies used known samples of vegetation types. An alternative approach, and the objective was to examine the above relationships by analyzing one year of AVHRR NDVI data that was stratified using a small-scale vegetation map of Mexico. The results show that there is a good relationship between AVHRR NDVI measurements and regional-scale vegetation dynamics of Mexico.

Is Anesthesia Technique Associated With a Higher Risk of Mortality or Complications Within 90 Days of Surgery for Geriatric Patients With Hip Fractures?

PubMed

Desai, Vimal; Chan, Priscilla H; Prentice, Heather A; Zohman, Gary L; Diekmann, Glenn R; Maletis, Gregory B; Fasig, Brian H; Diaz, Diana; Chung, Elena; Qiu, Chunyuan

2018-06-01

Postoperative mortality and complications after geriatric hip fracture surgery remain high despite efforts to improve perioperative care for these patients. One factor of particular interest is anesthetic technique, but prior studies on this are limited by sample selection, competing risks, and incomplete followup. (1) Among older patients undergoing surgery for hip fracture, does 90-day mortality differ depending on the type of anesthesia received? (2) Do 90-day emergency department returns and hospital readmissions differ based on anesthetic technique after geriatric hip fracture repairs? (3) Do 90-day Agency for Healthcare Research and Quality (AHRQ) outcomes differ according to anesthetic techniques used during hip fracture surgery? We conducted a retrospective study on geriatric patients (65 years or older) with hip fractures between 2009 and 2014 using the Kaiser Permanente Hip Fracture Registry. A total of 1995 (11%) of the surgically treated patients with hip fracture were excluded as a result of missing anesthesia information. The final study sample consisted of 16,695 patients. Of these, 2027 (12%) died and 98 (< 1%) terminated membership during followup, which were handled as competing events and censoring events, respectively. Ninety-day mortality, emergency department returns, hospital readmission, deep vein thrombosis (DVT) or pulmonary embolism (PE), myocardial infarction (MI), and pneumonia were evaluated using multivariable competing risk proportional subdistribution hazard regression according to type of anesthesia technique: general anesthesia, regional anesthesia, or conversion from regional to general. Of the 16,695 patients, 58% (N = 9629) received general anesthesia, 40% (N = 6597) received regional anesthesia, and 2.8% (N = 469) patients were converted from regional to general. Compared with regional anesthesia, patients treated with general anesthesia had a higher likelihood of overall 90-day mortality (hazard ratio [HR], 1.22; 95% confidence interval [CI], 1.11-1.35; p < 0.001); however, when stratified by before and after hospital discharge but within 90 days of surgery, this higher risk was only observed during the inpatient stay (HR, 3.83; 95% CI, 3.18-4.61; p < 0.001); no difference was observed after hospital discharge (HR, 1.04; 95% CI, 0.94-1.16; p = 0.408). Patients undergoing conversion from regional to general also had a higher overall mortality risk compared with those undergoing regional anesthesia (HR, 1.34; 95% CI 1.04-1.74; p = 0.026), but this risk was only observed during their inpatient stay (HR, 6.84; 95% CI, 4.21-11.11; p < 0.001) when stratifying by before and after hospital discharge. Patients undergoing general anesthesia had a higher risk for all-cause readmission when compared with regional anesthesia (HR, 1.09; 95% CI, 1.01-1.19; p = 0.026). No differences according to anesthesia type were observed for risk of 90-day AHRQ outcomes, including DVT/PE, MI, and pneumonia. We found the use of general anesthesia and conversion from regional to general anesthesia were associated with a higher risk of mortality during the in-hospital stay compared with regional anesthetic techniques, but this higher risk did not persist after hospital discharge. We also found general anesthesia to be associated with a higher risk of all-cause readmission compared with regional, but no other differences were observed in risk for complications. Our findings suggest regional anesthetic techniques may be preferred when possible in this patient population. Level III, therapeutic study.

Public Participation Guide: Citizen Juries

EPA Pesticide Factsheets

Citizen juries involve creating a “jury” a representative sample of citizens (usually selected in a random or stratified manner) who are briefed in detail on the background and current thinking relating to a particular issue or project.

A direct observation method for auditing large urban centers using stratified sampling, mobile GIS technology and virtual environments.

PubMed

Lafontaine, Sean J V; Sawada, M; Kristjansson, Elizabeth

2017-02-16

With the expansion and growth of research on neighbourhood characteristics, there is an increased need for direct observational field audits. Herein, we introduce a novel direct observational audit method and systematic social observation instrument (SSOI) for efficiently assessing neighbourhood aesthetics over large urban areas. Our audit method uses spatial random sampling stratified by residential zoning and incorporates both mobile geographic information systems technology and virtual environments. The reliability of our method was tested in two ways: first, in 15 Ottawa neighbourhoods, we compared results at audited locations over two subsequent years, and second; we audited every residential block (167 blocks) in one neighbourhood and compared the distribution of SSOI aesthetics index scores with results from the randomly audited locations. Finally, we present interrater reliability and consistency results on all observed items. The observed neighbourhood average aesthetics index score estimated from four or five stratified random audit locations is sufficient to characterize the average neighbourhood aesthetics. The SSOI was internally consistent and demonstrated good to excellent interrater reliability. At the neighbourhood level, aesthetics is positively related to SES and physical activity and negatively correlated with BMI. The proposed approach to direct neighbourhood auditing performs sufficiently and has the advantage of financial and temporal efficiency when auditing a large city.

Social Impact of Stigma Regarding Tuberculosis Hindering Adherence to Treatment: A Cross Sectional Study Involving Tuberculosis Patients in Rajshahi City, Bangladesh.

PubMed

Chowdhury, Md Rocky Khan; Rahman, Md Shafiur; Mondal, Md Nazrul Islam; Sayem, Abu; Billah, Baki

2015-01-01

Stigma, considered a social disease, is more apparent in developing societies which are driven by various social affairs, and influences adherence to treatment. The aim of the present study was to examine levels of social stigma related to tuberculosis (TB) in sociodemographic context and identify the effects of sociodemographic factors on stigma. The study sample consisted of 372 TB patients. Data were collected using stratified sampling with simple random sampling techniques. T tests, chi-square tests, and binary logistic regression analysis were performed to examine correlations between stigma and sociodemographic variables. Approximately 85.9% of patients had experienced stigma. The most frequent indicator of the stigma experienced by patients involved problems taking part in social programs (79.5%). Mean levels of stigma were significantly higher in women (55.5%), illiterate individuals (60.8%), and villagers (60.8%) relative to those of other groups. Chi-square tests revealed that education, monthly family income, and type of patient (pulmonary and extrapulmonary) were significantly associated with stigma. Binary logistic regression analysis demonstrated that stigma was influenced by sex, education, and type of patient. Stigma is one of the most important barriers to treatment adherence. Therefore, in interventions that aim to reduce stigma, strong collaboration between various institutions is essential.

A social impact assessment of the floodwater spreading project on the Gareh-Bygone plain in Iran: A causal comparative approach

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

Ahmadvand, Mostafa; Karami, Ezatollah

2009-02-15

The purpose of this study was to explore the social impacts of the floodwater spreading project (FWSP) on the Gareh-Bygone plain, Iran. The study was in the form of a causal comparative design, and a triangulation technique was used to collect data including the use of survey data, archival data, and a participatory rural appraisal (PRA). The causal comparative method requires a comparison of villages with and without the FWSP. Therefore, a survey was conducted using stratified random sampling to select 202 households in villages with and without FWSP in the plain. Significant differences were found between the respondents inmore » villages with and without FWSP with regard to social impact criteria. In spite of the project had negative impact on perceived wellbeing, social capital, social structure development; it had positive impact on quality of life, rural and agricultural economic conditions, and conservation of community resources. However, no significant difference was found between women and men regarding the SIA of FWSP in Gareh-Bygone plain. Analysis of the archival data and PRA techniques supported the survey results and demonstrated that the project improved environmental criteria and deteriorated social dimensions.« less

Methods and analysis of realizing randomized grouping.

PubMed

Hu, Liang-Ping; Bao, Xiao-Lei; Wang, Qi

2011-07-01

Randomization is one of the four basic principles of research design. The meaning of randomization includes two aspects: one is to randomly select samples from the population, which is known as random sampling; the other is to randomly group all the samples, which is called randomized grouping. Randomized grouping can be subdivided into three categories: completely, stratified and dynamically randomized grouping. This article mainly introduces the steps of complete randomization, the definition of dynamic randomization and the realization of random sampling and grouping by SAS software.

Study of Near-Surface Models in Large-Eddy Simulations of a Neutrally Stratified Atmospheric Boundary Layer

NASA Technical Reports Server (NTRS)

Senocak, I.; Ackerman, A. S.; Kirkpatrick, M. P.; Stevens, D. E.; Mansour, N. N.

2004-01-01

Large-eddy simulation (LES) is a widely used technique in armospheric modeling research. In LES, large, unsteady, three dimensional structures are resolved and small structures that are not resolved on the computational grid are modeled. A filtering operation is applied to distinguish between resolved and unresolved scales. We present two near-surface models that have found use in atmospheric modeling. We also suggest a simpler eddy viscosity model that adopts Prandtl's mixing length model (Prandtl 1925) in the vicinity of the surface and blends with the dynamic Smagotinsky model (Germano et al, 1991) away from the surface. We evaluate the performance of these surface models by simulating a neutraly stratified atmospheric boundary layer.

Lithofacies and seismic-reflection interpretation of temperate glacimarine sedimentation in Tarr Inlet, Glacier Bay, Alaska

USGS Publications Warehouse

Cai, J.; Powell, R.D.; Cowan, E.A.; Carlson, P.R.

1997-01-01

High-resolution seismic-reflection profiles of sediment fill within Tart Inlet of Glacier Bay, Alaska, show seismic facies changes with increasing distance from the glacial termini. Five types of seismic facies are recognized from analysis of Huntec and minisparker records, and seven lithofacies are determined from detailed sedimentologic study of gravity-, vibro- and box-cores, and bottom grab samples. Lithofacies and seismic facies associations, and fjord-floor morphology allow us to divide the fjord into three sedimentary environments: ice-proximal, iceberg-zone and ice-distal. The ice-proximal environment, characterized by a morainal-bank depositional system, can be subdivided into bank-back, bank-core and bank-front subenvironments, each of which is characterized by a different depositional subsystem. A bank-back subsystem shows chaotic seismic facies with a mounded surface, which we infer consists mainly of unsorted diamicton and poorly sorted coarse-grained sediments. A bank-core depositional subsystem is a mixture of diamicton, rubble, gravel, sand and mud. Seismic-reflection records of this subsystem are characterized by chaotic seismic facies with abundant hyperbolic diffractions and a hummocky surface. A bank-front depositional subsystem consists of mainly stratified and massive sand, and is characterized by internal hummocky facies on seismic-reflection records with significant surface relief and sediment gravity flow channels. The depositional system formed in the iceberg-zone environment consists of rhythmically laminated mud interbedded with thin beds of weakly stratified diamicton and stratified or massive sand and silt. On seismic-reflection profiles, this depositional system is characterized by discontinuously stratified facies with multiple channels on the surface in the proximal zone and a single channel on the largely flat sediment surface in the distal zone. The depositional system formed in the ice-distal environment consists of interbedded homogeneous or laminated mud and massive or stratified sand and coarse silt. This depositional system shows continuously stratified seismic facies with smooth and flat surfaces on minisparker records, and continuously stratified seismic facies which are interlayered with thin weakly stratified facies on Huntec records.

Determining storm sampling requirements for improving precision of annual load estimates of nutrients from a small forested watershed.

PubMed

Ide, Jun'ichiro; Chiwa, Masaaki; Higashi, Naoko; Maruno, Ryoko; Mori, Yasushi; Otsuki, Kyoichi

2012-08-01

This study sought to determine the lowest number of storm events required for adequate estimation of annual nutrient loads from a forested watershed using the regression equation between cumulative load (∑L) and cumulative stream discharge (∑Q). Hydrological surveys were conducted for 4 years, and stream water was sampled sequentially at 15-60-min intervals during 24 h in 20 events, as well as weekly in a small forested watershed. The bootstrap sampling technique was used to determine the regression (∑L-∑Q) equations of dissolved nitrogen (DN) and phosphorus (DP), particulate nitrogen (PN) and phosphorus (PP), dissolved inorganic nitrogen (DIN), and suspended solid (SS) for each dataset of ∑L and ∑Q. For dissolved nutrients (DN, DP, DIN), the coefficient of variance (CV) in 100 replicates of 4-year average annual load estimates was below 20% with datasets composed of five storm events. For particulate nutrients (PN, PP, SS), the CV exceeded 20%, even with datasets composed of more than ten storm events. The differences in the number of storm events required for precise load estimates between dissolved and particulate nutrients were attributed to the goodness of fit of the ∑L-∑Q equations. Bootstrap simulation based on flow-stratified sampling resulted in fewer storm events than the simulation based on random sampling and showed that only three storm events were required to give a CV below 20% for dissolved nutrients. These results indicate that a sampling design considering discharge levels reduces the frequency of laborious chemical analyses of water samples required throughout the year.

A System Approach to Navy Medical Education and Training. Appendix 18. Radiation Technician.

DTIC Science & Technology

1974-08-31

attrition was forecast to approximate twenty percent, final sample and sub-sample sizes were adjusted accordingly. Stratified random sampling... HYPERTENSIVE INTRAVENOUS PYELOGRAMS 2 ITAKE RENAL LOOPOGRAMI I 3 ITAKE CIXU, I.Eo CONSTANT INFUSION 4 10 RENAL SPLIT FUNCTION TEST, E.G. STAMEY 5...ITAKE PORTAL FILM OF AREA BEING TREATED WITH COBALT 32 [INFORM DOCTOR OF UNEXPECTED X-RAY FINDINGS 33 IREAD X-RAY FILMS FOR TECHNICAL ADEQUACY 34

Corrections of stratified tropospheric delays in SAR interferometry: Validation with global atmospheric models

NASA Astrophysics Data System (ADS)

Doin, Marie-Pierre; Lasserre, Cécile; Peltzer, Gilles; Cavalié, Olivier; Doubre, Cécile

2010-05-01

The main limiting factor on the accuracy of Interferometric SAR measurements (InSAR) comes from phase propagation delays through the troposphere. The delay can be divided into a stratified component, which correlates with the topography and often dominates the tropospheric signal, and a turbulent component. We use Global Atmospheric Models (GAM) to estimate the stratified phase delay and delay-elevation ratio at epochs of SAR acquisitions, and compare them to observed phase delay derived from SAR interferograms. Three test areas are selected with different geographic and climatic environments and with large SAR archive available. The Lake Mead, Nevada, USA is covered by 79 ERS1/2 and ENVISAT acquisitions, the Haiyuan Fault area, Gansu, China, by 24 ERS1/2 acquisitions, and the Afar region, Republic of Djibouti, by 91 Radarsat acquisitions. The hydrostatic and wet stratified delays are computed from GAM as a function of atmospheric pressure P, temperature T, and water vapor partial pressure e vertical profiles. The hydrostatic delay, which depends on ratio P/T, varies significantly at low elevation and cannot be neglected. The wet component of the delay depends mostly on the near surface specific humidity. GAM predicted delay-elevation ratios are in good agreement with the ratios derived from InSAR data away from deforming zones. Both estimations of the delay-elevation ratio can thus be used to perform a first order correction of the observed interferometric phase to retrieve a ground motion signal of low amplitude. We also demonstrate that aliasing of daily and seasonal variations in the stratified delay due to uneven sampling of SAR data significantly bias InSAR data stacks or time series produced after temporal smoothing. In all three test cases, the InSAR data stacks or smoothed time series present a residual stratified delay of the order of the expected deformation signal. In all cases, correcting interferograms from the stratified delay removes all these biases. We quantify the standard error associated with the correction of the stratified atmospheric delay. It varies from one site to another depending on the prevailing atmospheric conditions, but remains bounded by the standard deviation of the daily fluctuations of the stratified delay around the seasonal average. Finally we suggest that the phase delay correction can potentially be improved by introducing a non-linear dependence to the elevation derived from GAM.

Corrections of stratified tropospheric delays in SAR interferometry: Validation with global atmospheric models

NASA Astrophysics Data System (ADS)

Doin, M.-P.; Lasserre, C.; Peltzer, G.; Cavalié, O.; Doubre, C.

2009-09-01

The main limiting factor on the accuracy of Interferometric SAR measurements (InSAR) comes from phase propagation delays through the troposphere. The delay can be divided into a stratified component, which correlates with the topography and often dominates the tropospheric signal, and a turbulent component. We use Global Atmospheric Models (GAM) to estimate the stratified phase delay and delay-elevation ratio at epochs of SAR acquisitions, and compare them to observed phase delay derived from SAR interferograms. Three test areas are selected with different geographic and climatic environments and with large SAR archive available. The Lake Mead, Nevada, USA is covered by 79 ERS1/2 and ENVISAT acquisitions, the Haiyuan Fault area, Gansu, China, by 24 ERS1/2 acquisitions, and the Afar region, Republic of Djibouti, by 91 Radarsat acquisitions. The hydrostatic and wet stratified delays are computed from GAM as a function of atmospheric pressure P, temperature T, and water vapor partial pressure e vertical profiles. The hydrostatic delay, which depends on ratio P/ T, varies significantly at low elevation and cannot be neglected. The wet component of the delay depends mostly on the near surface specific humidity. GAM predicted delay-elevation ratios are in good agreement with the ratios derived from InSAR data away from deforming zones. Both estimations of the delay-elevation ratio can thus be used to perform a first order correction of the observed interferometric phase to retrieve a ground motion signal of low amplitude. We also demonstrate that aliasing of daily and seasonal variations in the stratified delay due to uneven sampling of SAR data significantly bias InSAR data stacks or time series produced after temporal smoothing. In all three test cases, the InSAR data stacks or smoothed time series present a residual stratified delay of the order of the expected deformation signal. In all cases, correcting interferograms from the stratified delay removes all these biases. We quantify the standard error associated with the correction of the stratified atmospheric delay. It varies from one site to another depending on the prevailing atmospheric conditions, but remains bounded by the standard deviation of the daily fluctuations of the stratified delay around the seasonal average. Finally we suggest that the phase delay correction can potentially be improved by introducing a non-linear dependence to the elevation derived from GAM.

NEKTON-HABITAT ASSOCIATIONS IN A PACIFIC NORTHWEST (USA) ESTUARY

EPA Science Inventory

Nekton−habitat associations were determined in Yaquina Bay, Oregon, United States, using a stratified-by-habitat, random, estuary-wide sampling design. Three habitats (intertidal eelgrass [Zostera marina], mud shrimp [Upogebia pugettensis], and ghost shrimp [Neotrypaea californie...

Theory of negative refraction in periodic stratified metamaterials.

PubMed

Rukhlenko, Ivan D; Premaratne, Malin; Agrawal, Govind P

2010-12-20

We present a general theory of negative refraction in periodic stratified heterostructures with an arbitrary number of homogeneous, isotropic, nonmagnetic layers in a unit cell. With a 4×4-matrix technique, we derive analytic expressions for the normal modes of such a heterostructure slab, introduce the average refraction angles of the energy flow and wavevector for the TE- and TM-polarized plane waves falling obliquely on the slab, and derive expressions for the reflectivity and transmissivity of the whole slab. For a specific case, in which all layers in a unit cell are much thinner than the wavelength of light, we obtain approximate simple formulae for the effective refraction angles. Using the example of a semiconductor heterostructure slab with two layers in a unit cell, we demonstrate that ultrathin layers are preferable for metamaterial applications because they enable higher transmissivity within the frequency band of negative refraction. Our theory can be used to study the optical properties of any stratified metamaterial, irrespective of whether semiconductors or metals are employed for fabricating its various layers, because it includes absorption within each layer.

Numerical simulation of turbulent stratified flame propagation in a closed vessel

NASA Astrophysics Data System (ADS)

Gruselle, Catherine; Lartigue, Ghislain; Pepiot, Perrine; Moureau, Vincent; D'Angelo, Yves

2012-11-01

Reducing pollutants emissions while keeping a high combustion efficiency and a low fuel consumption is an important challenge for both gas turbine (GT) and internal combustion engines (ICE). To fulfill these new constraints, stratified combustion may constitute an efficient strategy. A tabulated chemistry approach based on FPI combined to a low-Mach number method is applied in the analysis of a turbulent propane-air flame with equivalence ratio (ER) stratification, which has been studied experimentally by Balusamy [S. Balusamy, Ph.D Thesis, INSA-Rouen (2010)]. Flame topology, along with flame velocity statistics, are well reproduced in the simulation, even if time-history effects are not accounted for in the tabulated approach. However, these effects may become significant when exhaust gas recirculation (EGR) is introduced. To better quantify them, both ER and EGR-stratified two-dimensional flames are simulated using finite-rate chemistry and a semi-detailed mechanism for propane oxidation. The numerical implementation is first investigated in terms of efficiency and accuracy, with a focus on splitting errors. The resulting flames are then analyzed to investigate potential extensions of the FPI technique to EGR stratification.

The influence of IQ stratification on WAIS-III/WMS-III FSIQ-general memory index discrepancy base-rates in the standardization sample.

PubMed

Hawkins, K A; Tulsky, D S

2001-11-01

Since memory performance expectations may be IQ-based, unidirectional base rate data for IQ-Memory Score discrepancies are provided in the WAIS-III/WMS-III Technical Manual. The utility of these data partially rests on the assumption that discrepancy base rates do not vary across ability levels. FSIQ stratified base rate data generated from the standardization sample, however, demonstrate substantial variability across the IQ spectrum. A superiority of memory score over FSIQ is typical at lower IQ levels, whereas the converse is true at higher IQ levels. These data indicate that the use of IQ-memory score unstratified "simple difference" tables could lead to erroneous conclusions for clients with low or high IQ. IQ stratified standardization base rate data are provided as a complement to the "predicted difference" method detailed in the Technical Manual.

SAS procedures for designing and analyzing sample surveys

USGS Publications Warehouse

Stafford, Joshua D.; Reinecke, Kenneth J.; Kaminski, Richard M.

2003-01-01

Complex surveys often are necessary to estimate occurrence (or distribution), density, and abundance of plants and animals for purposes of re-search and conservation. Most scientists are familiar with simple random sampling, where sample units are selected from a population of interest (sampling frame) with equal probability. However, the goal of ecological surveys often is to make inferences about populations over large or complex spatial areas where organisms are not homogeneously distributed or sampling frames are in-convenient or impossible to construct. Candidate sampling strategies for such complex surveys include stratified,multistage, and adaptive sampling (Thompson 1992, Buckland 1994).

Technologies for Protein Analysis and Tissue Engineering, with Applications in Cancer

NASA Astrophysics Data System (ADS)

Vermesh, Udi Benjamin

The first part of this thesis describes electrolyte transport through an array of 20 nm wide, 20 mum long SiO2 nanofluidic transistors. At sufficiently low ionic strength, the Debye screening length exceeds the channel width, and ion transport is limited by the negatively charged channel surfaces. At source-drain biases > 5 V, the current exhibits a sharp, nonlinear increase, with a 20 - 50-fold conductance enhancement. This behavior is attributed to a breakdown of the zero-slip condition. Implications for peptide sequencing as well as energy conversion devices are discussed. The next part describes a technology for the detection of the highly aggressive brain cancer glioblastoma multiforme (GBM). In this study, we used an antibody-based microarray to compare plasma samples from glioblastoma patients and healthy controls with respect to the plasma levels of 35 different proteins known to be generally associated with tumor growth, survival, invasion, migration, and immune regulation. Average-linkage hierarchical clustering of the patient data stratified the two groups effectively, permitting accurate assignment of test samples into either GBM or healthy control groups with a sensitivity and specificity as high as 90 % and 94 %, respectively. Using the same 35-protein panel, we then analyzed plasma samples from GBM patients who were treated with the chemotherapeutic drug Avastin (Bevacizumab) and were able to effectively stratify patients based on treatment-responsiveness. Finally, single-cell resolution patterning of tissue engineered structures is demonstrated. The proper functioning of engineered constructs for tissue and organ transplantation requires positioning different cell types in anatomically precise arrangements that mimic their configurations in native tissues. Toward this end, we have developed a technique that involves two microfluidic-patterning steps run perpendicularly to each other using "anchor" and "bridge" DNA oligomers to create dense arrays of DNA grids which can then be converted into cell arrays. As a proof-of-concept, both a neuron-astrocyte construct and a pancreatic islet construct containing 2 distinct islet cell types were patterned separately as a dense array of cell grids. Once fixed in a hydrogel matrix, layers of patterned cells were then stacked to form 3-D tissue engineered constructs.

Variation between Hospitals with Regard to Diagnostic Practice, Coding Accuracy, and Case-Mix. A Retrospective Validation Study of Administrative Data versus Medical Records for Estimating 30-Day Mortality after Hip Fracture.

PubMed

Helgeland, Jon; Kristoffersen, Doris Tove; Skyrud, Katrine Damgaard; Lindman, Anja Schou

2016-01-01

The purpose of this study was to assess the validity of patient administrative data (PAS) for calculating 30-day mortality after hip fracture as a quality indicator, by a retrospective study of medical records. We used PAS data from all Norwegian hospitals (2005-2009), merged with vital status from the National Registry, to calculate 30-day case-mix adjusted mortality for each hospital (n = 51). We used stratified sampling to establish a representative sample of both hospitals and cases. The hospitals were stratified according to high, low and medium mortality of which 4, 3, and 5 hospitals were sampled, respectively. Within hospitals, cases were sampled stratified according to year of admission, age, length of stay, and vital 30-day status (alive/dead). The final study sample included 1043 cases from 11 hospitals. Clinical information was abstracted from the medical records. Diagnostic and clinical information from the medical records and PAS were used to define definite and probable hip fracture. We used logistic regression analysis in order to estimate systematic between-hospital variation in unmeasured confounding. Finally, to study the consequences of unmeasured confounding for identifying mortality outlier hospitals, a sensitivity analysis was performed. The estimated overall positive predictive value was 95.9% for definite and 99.7% for definite or probable hip fracture, with no statistically significant differences between hospitals. The standard deviation of the additional, systematic hospital bias in mortality estimates was 0.044 on the logistic scale. The effect of unmeasured confounding on outlier detection was small to moderate, noticeable only for large hospital volumes. This study showed that PAS data are adequate for identifying cases of hip fracture, and the effect of unmeasured case mix variation was small. In conclusion, PAS data are adequate for calculating 30-day mortality after hip-fracture as a quality indicator in Norway.

Oil-Water Flow Investigations using Planar-Laser Induced Fluorescence and Particle Velocimetry

NASA Astrophysics Data System (ADS)

Ibarra, Roberto; Matar, Omar K.; Markides, Christos N.

2017-11-01

The study of the complex behaviour of immiscible liquid-liquid flow in pipes requires the implementation of advanced measurement techniques in order to extract detailed in situ information. Laser-based diagnostic techniques allow the extraction of high-resolution space- and time resolve phase and velocity information, which aims to improve the fundamental understanding of these flows and to validate closure relations for advanced multiphase flow models. This work shows a novel simultaneous planar-laser induced fluorescence and particle velocimetry in stratified oil-water flows using two laser light sheets at two different wavelengths for fluids with different refractive indices at horizontal and upward pipe inclinations (<5°) in stratified flow conditions (i.e. separated layers). Complex flow structures are extracted from 2-D instantaneous velocity fields, which are strongly dependent on the pipe inclination at low velocities. The analysis of mean wall-normal velocity profiles and velocity fluctuations suggests the presence of single- and counter-rotating vortices in the azimuthal direction, especially in the oil layer, which can be attributed to the influence of the interfacial waves. Funding from BP, and the TMF Consortium is gratefully acknowledged.

Post-stratification sampling in small area estimation (SAE) model for unemployment rate estimation by Bayes approach

NASA Astrophysics Data System (ADS)

Hanike, Yusrianti; Sadik, Kusman; Kurnia, Anang

2016-02-01

This research implemented unemployment rate in Indonesia that based on Poisson distribution. It would be estimated by modified the post-stratification and Small Area Estimation (SAE) model. Post-stratification was one of technique sampling that stratified after collected survey data. It's used when the survey data didn't serve for estimating the interest area. Interest area here was the education of unemployment which separated in seven category. The data was obtained by Labour Employment National survey (Sakernas) that's collected by company survey in Indonesia, BPS, Statistic Indonesia. This company served the national survey that gave too small sample for level district. Model of SAE was one of alternative to solved it. According the problem above, we combined this post-stratification sampling and SAE model. This research gave two main model of post-stratification sampling. Model I defined the category of education was the dummy variable and model II defined the category of education was the area random effect. Two model has problem wasn't complied by Poisson assumption. Using Poisson-Gamma model, model I has over dispersion problem was 1.23 solved to 0.91 chi square/df and model II has under dispersion problem was 0.35 solved to 0.94 chi square/df. Empirical Bayes was applied to estimate the proportion of every category education of unemployment. Using Bayesian Information Criteria (BIC), Model I has smaller mean square error (MSE) than model II.

Poster — Thur Eve — 03: Application of the non-negative matrix factorization technique to [{sup 11}C]-DTBZ dynamic PET data for the early detection of Parkinson's disease

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

Lee, Dong-Chang; Jans, Hans; McEwan, Sandy

2014-08-15

In this work, a class of non-negative matrix factorization (NMF) technique known as alternating non-negative least squares, combined with the projected gradient method, is used to analyze twenty-five [{sup 11}C]-DTBZ dynamic PET/CT brain data. For each subject, a two-factor model is assumed and two factors representing the striatum (factor 1) and the non-striatum (factor 2) tissues are extracted using the proposed NMF technique and commercially available factor analysis software “Pixies”. The extracted factor 1 and 2 curves represent the binding site of the radiotracer and describe the uptake and clearance of the radiotracer by soft tissues in the brain, respectively.more » The proposed NMF technique uses prior information about the dynamic data to obtain sample time-activity curves representing the striatum and the non-striatum tissues. These curves are then used for “warm” starting the optimization. Factor solutions from the two methods are compared graphically and quantitatively. In healthy subjects, radiotracer uptake by factors 1 and 2 are approximately 35–40% and 60–65%, respectively. The solutions are also used to develop a factor-based metric for the detection of early, untreated Parkinson's disease. The metric stratifies healthy subjects from suspected Parkinson's patients (based on the graphical method). The analysis shows that both techniques produce comparable results with similar computational time. The “semi-automatic” approach used by the NMF technique allows clinicians to manually set a starting condition for “warm” starting the optimization in order to facilitate control and efficient interaction with the data.« less

The Relationship between School Achievement and Peer Harassment in Canadian Adolescents: The Importance of Mediating Factors

ERIC Educational Resources Information Center

Beran, Tanya N.; Lupart, Judy

2009-01-01

The relationship between school achievement and peer harassment was examined using individual and peer characteristics as mediating factors. The sample consisted of adolescents age 12-15 years (n = 4,111) drawn from the Canadian National Longitudinal Survey of Children and Youth, which is a stratified random sample of 22,831 households in Canada.…

Reduction of Racial Disparities in Prostate Cancer

DTIC Science & Technology

2005-12-01

erectile dysfunction , and female sexual dysfunction ). Wherever possible, the questions and scales employed on BACH were selected from published...Methods. A racially and ethnically diverse community-based survey of adults aged 30-79 years in Boston, Massachusetts. The BACH survey has...recruited adults in three racial/ethnic groups: Latino, African American, and White using a stratified cluster sample. The target sample size is equally

A Validation Study of the Revised Personal Safety Decision Scale

ERIC Educational Resources Information Center

Kim, HaeJung; Hopkins, Karen M.

2017-01-01

Objective: The purpose of this study is to examine the reliability and validity of an 11-item Personal Safety Decision Scale (PSDS) in a sample of child welfare workers. Methods: Data were derived from a larger cross-sectional online survey to a random stratified sample of 477 public child welfare workers in a mid-Atlantic State. An exploratory…

North Carolina's Summer School Program for High-Risk Students: A Two-Year Follow-Up of Student Achievement.

ERIC Educational Resources Information Center

Ward, Martha Szegda

The long-term effectiveness of the North Carolina Basic Education Summer School Program (BEP) was examined. North Carolina has instituted a testing and summer remediation program for academically at-risk students at grades 3, 6, and 8. The BEP sample was obtained by a stratified random sampling of schools in North Carolina. Results were…

Increasing the Precision of Estimates in Follow-Up Surveys: A Case Study. AIR 1983 Annual Forum Paper.

ERIC Educational Resources Information Center

Clark, Sheldon B.; Nichols, James O.

Survey data concerning teacher education program graduates were used to demonstrate the advantages of a stratified random sampling approach, with followup, relative to a one-shot mailing to an entire population. Sampling issues involved in such an approach are addressed, particularly with regard to quantifying the effects of nonresponse on the…

Survey Response in a Statewide Social Experiment: Differences in Being Located and Collaborating, by Race and Hispanic Origin

ERIC Educational Resources Information Center

Nam, Yunju; Mason, Lisa Reyes; Kim, Youngmi; Clancy, Margaret; Sherraden, Michael

2013-01-01

This study examined whether and how survey response differs by race and Hispanic origin, using data from birth certificates and survey administrative data for a large-scale statewide experiment. The sample consisted of mothers of infants selected from Oklahoma birth certificates using a stratified random sampling method (N = 7,111). This study…

Preserving America's Investment in Human Capital: A Study of Public Higher Education, 1980.

ERIC Educational Resources Information Center

Minter, W. John; Bowen, Howard R.

Financial and educational trends in accredited public institutions of higher education were studied for the period 1976-79 with some data for earlier years and for 1979-80. The study was based on a stratified sample of 135 institutions of which 95 participated. The sample represented all parts of the public sector except autonomous professional…

Teachers' Methodologies and Sources of Information on HIV/AIDS for Students with Visual Impairments in Selected Residential and Integrated Schools in Ghana

ERIC Educational Resources Information Center

Hayford, Samuel K.; Ocansey, Frederick

2017-01-01

This study reports part of a national survey on sources of information, education and communication materials on HIV/AIDS available to students with visual impairments in residential, segregated, and integrated schools in Ghana. A multi-staged stratified random sampling procedure and a purposive and simple random sampling approach, where…

Modeling of Academic Achievement of Primary School Students in Ethiopia Using Bayesian Multilevel Approach

ERIC Educational Resources Information Center

Sebro, Negusse Yohannes; Goshu, Ayele Taye

2017-01-01

This study aims to explore Bayesian multilevel modeling to investigate variations of average academic achievement of grade eight school students. A sample of 636 students is randomly selected from 26 private and government schools by a two-stage stratified sampling design. Bayesian method is used to estimate the fixed and random effects. Input and…

Development of Creative Behavior Observation Form: A Study on Validity and Reliability

ERIC Educational Resources Information Center

Dere, Zeynep; Ömeroglu, Esra

2018-01-01

This study, Creative Behavior Observation Form was developed to assess creativity of the children. While the study group on the reliability and validity of Creative Behavior Observation Form was being developed, 257 children in total who were at the ages of 5-6 were used as samples with stratified sampling method. Content Validity Index (CVI) and…

High resolution satellite remote sensing used in a stratified random sampling scheme to quantify the constituent land cover components of the shifting cultivation mosaic of the Democratic Republic of Congo

NASA Astrophysics Data System (ADS)

Molinario, G.; Hansen, M.; Potapov, P.

2016-12-01

High resolution satellite imagery obtained from the National Geospatial Intelligence Agency through NASA was used to photo-interpret sample areas within the DRC. The area sampled is a stratifcation of the forest cover loss from circa 2014 that either occurred completely within the previosly mapped homogenous area of the Rural Complex, at it's interface with primary forest, or in isolated forest perforations. Previous research resulted in a map of these areas that contextualizes forest loss depending on where it occurs and with what spatial density, leading to a better understading of the real impacts on forest degradation of livelihood shifting cultivation. The stratified random sampling approach of these areas allows the characterization of the constituent land cover types within these areas, and their variability throughout the DRC. Shifting cultivation has a variable forest degradation footprint in the DRC depending on many factors that drive it, but it's role in forest degradation and deforestation had been disputed, leading us to investigate and quantify the clearing and reuse rates within the strata throughout the country.

Scalable Performance Measurement and Analysis

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

Gamblin, Todd

2009-01-01

Concurrency levels in large-scale, distributed-memory supercomputers are rising exponentially. Modern machines may contain 100,000 or more microprocessor cores, and the largest of these, IBM's Blue Gene/L, contains over 200,000 cores. Future systems are expected to support millions of concurrent tasks. In this dissertation, we focus on efficient techniques for measuring and analyzing the performance of applications running on very large parallel machines. Tuning the performance of large-scale applications can be a subtle and time-consuming task because application developers must measure and interpret data from many independent processes. While the volume of the raw data scales linearly with the number ofmore » tasks in the running system, the number of tasks is growing exponentially, and data for even small systems quickly becomes unmanageable. Transporting performance data from so many processes over a network can perturb application performance and make measurements inaccurate, and storing such data would require a prohibitive amount of space. Moreover, even if it were stored, analyzing the data would be extremely time-consuming. In this dissertation, we present novel methods for reducing performance data volume. The first draws on multi-scale wavelet techniques from signal processing to compress systemwide, time-varying load-balance data. The second uses statistical sampling to select a small subset of running processes to generate low-volume traces. A third approach combines sampling and wavelet compression to stratify performance data adaptively at run-time and to reduce further the cost of sampled tracing. We have integrated these approaches into Libra, a toolset for scalable load-balance analysis. We present Libra and show how it can be used to analyze data from large scientific applications scalably.« less

Sample size calculations for cluster randomised crossover trials in Australian and New Zealand intensive care research.

PubMed

Arnup, Sarah J; McKenzie, Joanne E; Pilcher, David; Bellomo, Rinaldo; Forbes, Andrew B

2018-06-01

The cluster randomised crossover (CRXO) design provides an opportunity to conduct randomised controlled trials to evaluate low risk interventions in the intensive care setting. Our aim is to provide a tutorial on how to perform a sample size calculation for a CRXO trial, focusing on the meaning of the elements required for the calculations, with application to intensive care trials. We use all-cause in-hospital mortality from the Australian and New Zealand Intensive Care Society Adult Patient Database clinical registry to illustrate the sample size calculations. We show sample size calculations for a two-intervention, two 12-month period, cross-sectional CRXO trial. We provide the formulae, and examples of their use, to determine the number of intensive care units required to detect a risk ratio (RR) with a designated level of power between two interventions for trials in which the elements required for sample size calculations remain constant across all ICUs (unstratified design); and in which there are distinct groups (strata) of ICUs that differ importantly in the elements required for sample size calculations (stratified design). The CRXO design markedly reduces the sample size requirement compared with the parallel-group, cluster randomised design for the example cases. The stratified design further reduces the sample size requirement compared with the unstratified design. The CRXO design enables the evaluation of routinely used interventions that can bring about small, but important, improvements in patient care in the intensive care setting.

Knowledge, attitude, and practice (KAP) of food hygiene among schools students' in Majmaah city, Saudi Arabia.

PubMed

Almansour, Mohammed; Sami, Waqas; Al-Rashedy, Oliyan Shoqer; Alsaab, Rayan Saad; Alfayez, Abdulrahman Saad; Almarri, Nawaf Rashed

2016-04-01

To determine the level of knowledge, attitude, and practice of food hygiene among primary, intermediate and high school students and explore association, if any, with socio-demographic differences. The observational cross-sectional study was conducted at boy's schools in Majmaah, Kingdom of Saudi Arabia, from February to May 2014. Data was collected using stratified random sampling technique from students aged 8-25 year. Two schools from each level (primary, intermediate and high school) were randomly selected and data was collected from the selected schools using simple random sampling method. A self-administered modified Sharif and Al-Malki questionnaire for knowledge, attitude and practice of food hygiene was used with Arabic translation. The mean age of 377 male students in the study was 14.53±2.647 years. Knowledge levels was less in primary school students compared to high school students (p=0.026). Attitude level was high in primary school students compared to intermediate school students (p< 0.001). No significant difference was observed between groups with regard to practice levels (p=0.152). The students exhibited good practice levels, despite fair knowledge and attitude levels.

Geohydrology and water quality of stratified-drift aquifers in the lower Merrimack and coastal river basins, southeastern New Hampshire

USGS Publications Warehouse

Stekl, Peter J.; Flanagan, Sarah M.

1992-01-01

Communities in the lower Merrimack River basin and coastal river basins of southeastern New Hampshire are experiencing increased demands for water because of a rapid increase in population. The population in 1987 was 225,495 and is expected to increase by 30 percent during the next decade. As of 1987, five towns used the stratified-drift aquifers for municipal supply and withdrew an estimated 6 million gallons per day. Four towns used the bedrock aquifer for municipal supply and withdrew an average of 1 .6 million gallons per day. Stratified-drift deposits cover 78 of the 327 square miles of the study area. These deposits are generally less than 10 square miles in areal extent, and their saturated thickness ranges front less than 20 feet to as much as 100 feet . Transinissivity exceeds 4,000 square feet per day in several locations. Stratified-drift aquifers in the eastern part are predominantly small ice-contact deposits surrounded by marine sediments or till of low hydraulic conductivity. Stratified-drift aquifers in the western part consist of ice-contact and proglacial deposits that are large in areal extent and are commonly in contact with surface-water bodies. Five stratified-drift aquifers, in the towns of Derry, Windham, Kingston, North Hampton, and Greenland, have the greatest potential to supply additional amounts of water. Potential yields and contributing areas of hypothetical supply wells were estimated for an aquifer in Windham near Cobbetts Pond and for an aquifer in Kingston along the Powwow River by use of a method analogous to superposition in conjunction with a numerical ground-waterflow model. The potential yield is estimated to be 0 .6 million gallons per day for the Windham-Cobbetts Pond aquifer and 4 .0 million gallons per day for the Kingston-Powwow River aquifer. Contributing recharge area for supply wells is estimated to be 1.6 square miles in the Windham-Cobbetts Pond aquifer and 4.9 square miles in the Kingston-Powwow River aquifer. Analyses of water samples from 30 wells indicate that the water quality in the basins studied is generally suitable for drinking and other domestic purposes. Concentrations of iron and manganese exceeded the U.S . Environmental Protection Agency's (USEPA) and the New Hampshire Water Supply Engineering Bureau's secondary maximum contaminant levels for drinking water in 20 samples. With one exception, concentrations of volatile organic compounds at all wells sampled met New Hampshire Water Supply and Engineering Bureau's drinking-water standards. At one well, trichloroethylene was detected at a concentration of 5.7 micrograms per liter. Ground-water contamination has been detected at several hazardous-waste sites in the study area. Currently, 5 sites are on the USEPA's National Priority List of superfund sites, 10 sites are Resource Conservation and Recovery Act of 1976 sites, and 1 site is a Department of Defense hazardous-waste site of stratigraphic layers is a product of a material's density and the velocity at which sound travels through that material . The reflected signals return to the hydrophones at the water surface and are then filtered, amplified, and displayed graphically on the chart recorder to allow interpretation of aquifer stratigraphy and bedrock depths. Lithologic data from nearby wells and test holes were used as control points to check the interpretation of the reflection profiles. Test drilling was done at 66 locations (pls . 1-3) to determine sediment grain size, stratigraphy, depth to water table, depth to bedrock, and ground water quality . A 6-inch-diameter, hollow-stem auger was used for test drilling . Split-spoon samples of subsurface materials collected at specific depths were used to evaluate the grain-size characteristics and identify the stratigraphic sequence of materials comprising the aquifers . Thirty-eight test holes cased with a 2-inch-diameter polyvinyl-chloride (PVC) pipe and slotted screens were used to make ground-water-level measurements and collect ground-water-quality samples. Surface-water-discharge measurements were made at 16 sites during low flow when the surface water is primarily ground-water discharge . These low-flow measurements indicate quantities of ground water potentially available from aquifers. Hydraulic conductivities of aquifer materials were estimated from grain-size-distribution data from 61 samples of stratified drift . Transmissivity was estimated from well logs by assigning hydraulic conductivity to specific well-log intervals, multiplying by the saturated thickness of the interval, and summing the results . Additional transmissivity values were obtained from an analysis of specific capacity and aquifer-test data. Long-term aquifer yields and contributing areas to hypothetical supply wells were estimated by application of a method that is analogous to super position and incorporates a ground-water-flow model developed by McDonald and Harbaugh (1988) . This method was applied to two aquifers judged to have the best potential for providing additional ground-water supplies. Samples of ground water from 26 test wells and 4 municipal wells were collected in March and August 1987 for analysis of common inorganic, organic, and volatile organic constituents. Methods for collecting and analyzing the samples are described by Fishman and Freidman (1989) . The water-quality results from the well samples were used to characterize background water quality in the stratified-drift aquifers.

Mapping spatial resources with GPS animal telemetry: foraging manatees locate seagrass beds in the Ten Thousand Islands, Florida, USA

USGS Publications Warehouse

Slone, Daniel H.; Reid, James P.; Kenworthy, W. Judson

2013-01-01

Turbid water conditions make the delineation and characterization of benthic habitats difficult by traditional in situ and remote sensing methods. Here, we develop and validate modeling and sampling methodology for detecting and characterizing seagrass beds by analyzing GPS telemetry records from radio-tagged manatees. Between October 2002 and October 2005, 14 manatees were tracked in the Ten Thousand Islands (TTI) in southwest Florida (USA) using Global Positioning System (GPS) tags. High density manatee use areas were found to occur off each island facing the open, nearshore waters of the Gulf of Mexico. We implemented a spatially stratified random sampling plan and used a camera-based sampling technique to observe and record bottom observations of seagrass and macroalgae presence and abundance. Five species of seagrass were identified in our study area: Halodule wrightii, Thalassia testudinum, Syringodium filiforme, Halophila engelmannii, and Halophila decipiens. A Bayesian model was developed to choose and parameterize a spatial process function that would describe the observed patterns of seagrass and macroalgae. The seagrasses were found in depths <2 m and in the higher manatee use strata, whereas macroalgae was found at moderate densities at all sampled depths and manatee use strata. The manatee spatial data showed a strong association with seagrass beds, a relationship that increased seagrass sampling efficiency. Our camera-based field sampling proved to be effective for assessing seagrass density and spatial coverage under turbid water conditions, and would be an effective monitoring tool to detect changes in seagrass beds.

Scientific Reasoning and Its Relationship with Problem Solving: The Case of Upper Primary Science Teachers

ERIC Educational Resources Information Center

Alshamali, Mahmoud A.; Daher, Wajeeh M.

2016-01-01

This study aimed at identifying the levels of scientific reasoning of upper primary stage (grades 4-7) science teachers based on their use of a problem-solving strategy. The study sample (N = 138; 32 % male and 68 % female) was randomly selected using stratified sampling from an original population of 437 upper primary school teachers. The…

Sexual Sensation Seeking, Social Stress, and Coping Styles as Predictors of HIV/STD Risk Behaviors in Adolescents

ERIC Educational Resources Information Center

Teva, Inmaculada; Bermudez, Maria Paz; Buela-Casal, Gualberto

2010-01-01

The aim of this study was to assess whether coping styles, social stress, and sexual sensation seeking were predictors of HIV/STD risk behaviours in adolescents. A representative sample of 4,456 female and male Spanish high school students aged 13 to 18 years participated. A stratified random sampling procedure was used. Self-report questionnaires…

The Relationship of Family Satisfaction to Satisfaction with the Military Way of Life among Soldiers. Technical Report 864.

ERIC Educational Resources Information Center

Bowen, Gary L.

This study investigated the relationship between soldiers' satisfaction with the environment for families in the Army and satisfaction with the military way of life. The report is based on a secondary analysis of the responses of a stratified random sample of 9,198 Army personnel, a sample that participated in the 1985 Department of Defense…

National-scale crop type mapping and area estimation using multi-resolution remote sensing and field survey

NASA Astrophysics Data System (ADS)

Song, X. P.; Potapov, P.; Adusei, B.; King, L.; Khan, A.; Krylov, A.; Di Bella, C. M.; Pickens, A. H.; Stehman, S. V.; Hansen, M.

2016-12-01

Reliable and timely information on agricultural production is essential for ensuring world food security. Freely available medium-resolution satellite data (e.g. Landsat, Sentinel) offer the possibility of improved global agriculture monitoring. Here we develop and test a method for estimating in-season crop acreage using a probability sample of field visits and producing wall-to-wall crop type maps at national scales. The method is first illustrated for soybean cultivated area in the US for 2015. A stratified, two-stage cluster sampling design was used to collect field data to estimate national soybean area. The field-based estimate employed historical soybean extent maps from the U.S. Department of Agriculture (USDA) Cropland Data Layer to delineate and stratify U.S. soybean growing regions. The estimated 2015 U.S. soybean cultivated area based on the field sample was 341,000 km2 with a standard error of 23,000 km2. This result is 1.0% lower than USDA's 2015 June survey estimate and 1.9% higher than USDA's 2016 January estimate. Our area estimate was derived in early September, about 2 months ahead of harvest. To map soybean cover, the Landsat image archive for the year 2015 growing season was processed using an active learning approach. Overall accuracy of the soybean map was 84%. The field-based sample estimated area was then used to calibrate the map such that the soybean acreage of the map derived through pixel counting matched the sample-based area estimate. The strength of the sample-based area estimation lies in the stratified design that takes advantage of the spatially explicit cropland layers to construct the strata. The success of the mapping was built upon an automated system which transforms Landsat images into standardized time-series metrics. The developed method produces reliable and timely information on soybean area in a cost-effective way and could be implemented in an operational mode. The approach has also been applied for other crops in other regions, such as winter wheat in Pakistan, soybean in Argentina and soybean in the entire South America. Similar levels of accuracy and timeliness were achieved as in the US.

2001 traffic safety issues opinion survey.

DOT National Transportation Integrated Search

2002-02-01

As a means of determining public opinion on specific traffic safety issues, a public opinion survey was conducted. A total of 4,500 mail surveys were sent to a stratified sample of drivers selected from the drivers license file. The state was divided...

Data processing technique for multiangle lidar sounding of poorly stratified polluted atmospheres: Theory and experiment

Treesearch

Cyle E. Wold; Vladimir A. Kovalev; Alexander P. Petkov; Wei Min Hao

2012-01-01

Scanning elastic lidar, which can operate in different slant directions, is the most appropriate remote sensing tool for investigating the optical properties of smoke-polluted atmospheres. However, the commonly used methodologies of multiangle measurements are based on the assumption of horizontal stratification of the searched atmosphere1,2. When working in real...

Profiling of poorly stratified smoky atmospheres with scanning lidar

Treesearch

Vladimir Kovalev; Cyle Wold; Alexander Petkov; Wei Min Hao

2012-01-01

The multiangle data processing technique is considered based on using the signal measured in zenith (or close to zenith) as a core source for extracting the information about the vertical atmospheric aerosol loading. The multiangle signals are used as the auxiliary data to extract the vertical transmittance profile from the zenith signal. Simulated and experimental...

Effects of unstratified and centre-stratified randomization in multi-centre clinical trials.

PubMed

Anisimov, Vladimir V

2011-01-01

This paper deals with the analysis of randomization effects in multi-centre clinical trials. The two randomization schemes most often used in clinical trials are considered: unstratified and centre-stratified block-permuted randomization. The prediction of the number of patients randomized to different treatment arms in different regions during the recruitment period accounting for the stochastic nature of the recruitment and effects of multiple centres is investigated. A new analytic approach using a Poisson-gamma patient recruitment model (patients arrive at different centres according to Poisson processes with rates sampled from a gamma distributed population) and its further extensions is proposed. Closed-form expressions for corresponding distributions of the predicted number of the patients randomized in different regions are derived. In the case of two treatments, the properties of the total imbalance in the number of patients on treatment arms caused by using centre-stratified randomization are investigated and for a large number of centres a normal approximation of imbalance is proved. The impact of imbalance on the power of the study is considered. It is shown that the loss of statistical power is practically negligible and can be compensated by a minor increase in sample size. The influence of patient dropout is also investigated. The impact of randomization on predicted drug supply overage is discussed. Copyright © 2010 John Wiley & Sons, Ltd.

Health literacy in old age: results of a German cross-sectional study.

PubMed

Vogt, Dominique; Schaeffer, Doris; Messer, Melanie; Berens, Eva-Maria; Hurrelmann, Klaus

2017-03-22

Health literacy is especially important for older people to maintain or enhance remaining health resources and self-management skills. The aim of the study was to determine the level of health literacy and the association between health literacy, demographic and socio-economic factors in German older adults aged 65 years and above stratified by age group. Health literacy was assessed via computer-assisted personal interviews using HLS-EU-Q47 on a representative sample of the German-speaking population. Descriptive statistics, bivariate analyses and logistic regression modelling stratified by age group were conducted to assess health literacy of 475 respondents aged 65 years and above. Overall, 66.3% of all respondents aged 65 years and above had limited health literacy. Limited health literacy was especially prevalent among respondents above 76 years of age (80.6%). Limited health literacy was associated with financial deprivation (OR: 3.05; 95% CI: 1.99-4.67) and limited functional health literacy (OR: 2.16; 95% CI: 1.29-3.61). Financial deprivation was strongest predictor for limited health literacy in the total sample and stratified by age group. Limited health literacy is a frequent phenomenon in German adults aged 65 years and above. Research on health literacy in old age and the role in health disparities is urgently needed. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Direct Numerical Simulation of a Weakly Stratified Turbulent Wake

NASA Technical Reports Server (NTRS)

Redford, J. A.; Lund, T. S.; Coleman, Gary N.

2014-01-01

Direct numerical simulation (DNS) is used to investigate a time-dependent turbulent wake evolving in a stably stratified background. A large initial Froude number is chosen to allow the wake to become fully turbulent and axisymmetric before stratification affects the spreading rate of the mean defect. The uncertainty introduced by the finite sample size associated with gathering statistics from a simulation of a time-dependent flow is reduced, compared to earlier simulations of this flow. The DNS reveals the buoyancy-induced changes to the turbulence structure, as well as to the mean-defect history and the terms in the mean-momentum and turbulence-kinetic-energy budgets, that characterize the various states of this flow - namely the three-dimensional (essentially unstratified), non-equilibrium (or 'wake-collapse') and quasi-two-dimensional (or 'two-component') regimes observed elsewhere for wakes embedded in both weakly and strongly stratified backgrounds. The wake-collapse regime is not accompanied by transfer (or 'reconversion') of the potential energy of the turbulence to the kinetic energy of the turbulence, implying that this is not an essential feature of stratified-wake dynamics. The dependence upon Reynolds number of the duration of the wake-collapse period is demonstrated, and the effect of the details of the initial/near-field conditions of the wake on its subsequent development is examined.

Improved Horvitz-Thompson Estimation of Model Parameters from Two-phase Stratified Samples: Applications in Epidemiology

PubMed Central

Breslow, Norman E.; Lumley, Thomas; Ballantyne, Christie M; Chambless, Lloyd E.; Kulich, Michal

2009-01-01

The case-cohort study involves two-phase sampling: simple random sampling from an infinite super-population at phase one and stratified random sampling from a finite cohort at phase two. Standard analyses of case-cohort data involve solution of inverse probability weighted (IPW) estimating equations, with weights determined by the known phase two sampling fractions. The variance of parameter estimates in (semi)parametric models, including the Cox model, is the sum of two terms: (i) the model based variance of the usual estimates that would be calculated if full data were available for the entire cohort; and (ii) the design based variance from IPW estimation of the unknown cohort total of the efficient influence function (IF) contributions. This second variance component may be reduced by adjusting the sampling weights, either by calibration to known cohort totals of auxiliary variables correlated with the IF contributions or by their estimation using these same auxiliary variables. Both adjustment methods are implemented in the R survey package. We derive the limit laws of coefficients estimated using adjusted weights. The asymptotic results suggest practical methods for construction of auxiliary variables that are evaluated by simulation of case-cohort samples from the National Wilms Tumor Study and by log-linear modeling of case-cohort data from the Atherosclerosis Risk in Communities Study. Although not semiparametric efficient, estimators based on adjusted weights may come close to achieving full efficiency within the class of augmented IPW estimators. PMID:20174455

On the Exploitation of Sensitivity Derivatives for Improving Sampling Methods

NASA Technical Reports Server (NTRS)

Cao, Yanzhao; Hussaini, M. Yousuff; Zang, Thomas A.

2003-01-01

Many application codes, such as finite-element structural analyses and computational fluid dynamics codes, are capable of producing many sensitivity derivatives at a small fraction of the cost of the underlying analysis. This paper describes a simple variance reduction method that exploits such inexpensive sensitivity derivatives to increase the accuracy of sampling methods. Three examples, including a finite-element structural analysis of an aircraft wing, are provided that illustrate an order of magnitude improvement in accuracy for both Monte Carlo and stratified sampling schemes.

Validity of self-reported stroke in elderly African Americans, Caribbean Hispanics, and Whites.

PubMed

Reitz, Christiane; Schupf, Nicole; Luchsinger, José A; Brickman, Adam M; Manly, Jennifer J; Andrews, Howard; Tang, Ming X; DeCarli, Charles; Brown, Truman R; Mayeux, Richard

2009-07-01

The validity of a self-reported stroke remains inconclusive. To validate the diagnosis of self-reported stroke using stroke identified by magnetic resonance imaging (MRI) as the standard. Community-based cohort study of nondemented, ethnically diverse elderly persons in northern Manhattan. High-resolution quantitative MRIs were acquired for 717 participants without dementia. Sensitivity and specificity of stroke by self-report were examined using cross-sectional analyses and the chi(2) test. Putative relationships between factors potentially influencing the reporting of stroke, including memory performance, cognitive function, and vascular risk factors, were assessed using logistic regression models. Subsequently, all analyses were repeated, stratified by age, sex, ethnic group, and level of education. In analyses of the whole sample, sensitivity of stroke self-report for a diagnosis of stroke on MRI was 32.4%, and specificity was 78.9%. In analyses stratified by median age (80.1 years), the validity between reported stroke and detection of stroke on MRI was significantly better in the younger than the older age group (for all vascular territories: sensitivity and specificity, 36.7% and 81.3% vs 27.6% and 26.2%; P = .02). Impaired memory, cognitive skills, or language ability and the presence of hypertension or myocardial infarction were associated with higher rates of false-negative results. Using brain MRI as the standard, specificity and sensitivity of stroke self-report are low. Accuracy of self-report is influenced by age, presence of vascular disease, and cognitive function. In stroke research, sensitive neuroimaging techniques rather than stroke self-report should be used to determine stroke history.

Effect of low-level laser therapy (LLLT) and light-emitting diodes (LEDT) applied during combined training on performance and post-exercise recovery: protocol for a randomized placebo-controlled trial.

PubMed

Machado, Aryane Flauzino; Micheletti, Jéssica Kirsch; Vanderlei, Franciele Marques; Nakamura, Fabio Yuzo; Leal-Junior, Ernesto Cesar Pinto; Netto Junior, Jayme; Pastre, Carlos Marcelo

Previous studies have shown positive results of phototherapy for improving performance and accelerating recovery; however, the effects of phototherapy during training and after a primary adaptation remain unclear. The aim of this randomized controlled trial is to analyze the effects of phototherapy and combined training on clinical, functional, and psychological outcomes and on vascular endothelial growth factor. This randomized placebo-controlled trial by stratified sample will involve 45 healthy male participants. In phase 1, the participants will undergo six weeks of combined training (sprints and squats). In phase 2, participants will be allocated through stratified randomization (based on adaptation capacity) into three groups: active phototherapy group (AG), placebo group (PG), and non-treatment control group (CG). A new six-week training program will then start and the participants will receive the recovery strategy between sprints and squats. The primary outcome will be maximal isometric contraction. The secondary outcomes include strength and power testing, maximal incremental test, squat jump, sprint test, muscle soreness, pain threshold, perceptions of exertion and recovery, psychological questionnaire, and vascular endothelial growth factor. This will be the first trial to include phototherapy during training. We believe that this strategy will combine the ergogenic and prophylactic effects in the same session. Furthermore, an application protocol performed after primary adaptation may reflect the real effect of the technique. Copyright © 2017 Associação Brasileira de Pesquisa e Pós-Graduação em Fisioterapia. Publicado por Elsevier Editora Ltda. All rights reserved.

A technique system for the measurement, reconstruction and character extraction of rice plant architecture

PubMed Central

Li, Xumeng; Wang, Xiaohui; Wei, Hailin; Zhu, Xinguang; Peng, Yulin; Li, Ming; Li, Tao; Huang, Huang

2017-01-01

This study developed a technique system for the measurement, reconstruction, and trait extraction of rice canopy architectures, which have challenged functional–structural plant modeling for decades and have become the foundation of the design of ideo-plant architectures. The system uses the location-separation-measurement method (LSMM) for the collection of data on the canopy architecture and the analytic geometry method for the reconstruction and visualization of the three-dimensional (3D) digital architecture of the rice plant. It also uses the virtual clipping method for extracting the key traits of the canopy architecture such as the leaf area, inclination, and azimuth distribution in spatial coordinates. To establish the technique system, we developed (i) simple tools to measure the spatial position of the stem axis and azimuth of the leaf midrib and to capture images of tillers and leaves; (ii) computer software programs for extracting data on stem diameter, leaf nodes, and leaf midrib curves from the tiller images and data on leaf length, width, and shape from the leaf images; (iii) a database of digital architectures that stores the measured data and facilitates the reconstruction of the 3D visual architecture and the extraction of architectural traits; and (iv) computation algorithms for virtual clipping to stratify the rice canopy, to extend the stratified surface from the horizontal plane to a general curved surface (including a cylindrical surface), and to implement in silico. Each component of the technique system was quantitatively validated and visually compared to images, and the sensitivity of the virtual clipping algorithms was analyzed. This technique is inexpensive and accurate and provides high throughput for the measurement, reconstruction, and trait extraction of rice canopy architectures. The technique provides a more practical method of data collection to serve functional–structural plant models of rice and for the optimization of rice canopy types. Moreover, the technique can be easily adapted for other cereal crops such as wheat, which has numerous stems and leaves sheltering each other. PMID:28558045

Cardiorespiratory Fitness Levels among U.S. Youth Aged 12-15 Years: United States, 1999-2004 and 2012

MedlinePlus

... use a complex, stratified, multistage probability cluster sampling design. NHANES data collection is based on a nationally ... conjunction with the 2012 NHANES and the survey design was based on the design for NHANES, with ...

Dietary Supplement Use Among U.S. Adults Has Increased Since NHANES III (1988-1994)

MedlinePlus

... uses a complex, stratified, multistage probability cluster sampling design and oversamples in order to increase precision in estimates for certain groups. NHANES III was one in a series of periodic surveys conducted in two cycles during ...

Frequency of distracting tasks people do while driving : an analysis of the ACAS FOT data.

DOT National Transportation Integrated Search

2007-06-01

This report describes further analysis of data from the advanced collision avoidance system (ACAS) field operational test, a naturalistic driving study. To determine how distracted and nondistracted driving differ, a stratified sample of 2,914 video ...

Assessment of the effect of population and diary sampling methods on estimation of school-age children exposure to fine particles.

PubMed

Che, W W; Frey, H Christopher; Lau, Alexis K H

2014-12-01

Population and diary sampling methods are employed in exposure models to sample simulated individuals and their daily activity on each simulation day. Different sampling methods may lead to variations in estimated human exposure. In this study, two population sampling methods (stratified-random and random-random) and three diary sampling methods (random resampling, diversity and autocorrelation, and Markov-chain cluster [MCC]) are evaluated. Their impacts on estimated children's exposure to ambient fine particulate matter (PM2.5 ) are quantified via case studies for children in Wake County, NC for July 2002. The estimated mean daily average exposure is 12.9 μg/m(3) for simulated children using the stratified population sampling method, and 12.2 μg/m(3) using the random sampling method. These minor differences are caused by the random sampling among ages within census tracts. Among the three diary sampling methods, there are differences in the estimated number of individuals with multiple days of exposures exceeding a benchmark of concern of 25 μg/m(3) due to differences in how multiday longitudinal diaries are estimated. The MCC method is relatively more conservative. In case studies evaluated here, the MCC method led to 10% higher estimation of the number of individuals with repeated exposures exceeding the benchmark. The comparisons help to identify and contrast the capabilities of each method and to offer insight regarding implications of method choice. Exposure simulation results are robust to the two population sampling methods evaluated, and are sensitive to the choice of method for simulating longitudinal diaries, particularly when analyzing results for specific microenvironments or for exposures exceeding a benchmark of concern. © 2014 Society for Risk Analysis.

Should studies of risk factors for musculoskeletal disorders be stratified by gender? Lessons from the 1998 Québec Health and Social Survey.

PubMed

Messing, Karen; Stock, Susan R; Tissot, France

2009-03-01

Several studies have reported male-female differences in the prevalence of symptoms of work-related musculoskeletal disorders (MSD), some arising from workplace exposure differences. The objective of this paper was to compare two strategies analyzing a single dataset for the relationships between risk factors and MSD in a population-based sample with a wide range of exposures. The 1998 Québec Health and Social Survey surveyed 11 735 respondents in paid work and reported "significant" musculoskeletal pain in 11 body regions during the previous 12 months and a range of personal, physical, and psychosocial risk factors. Five studies concerning risk factors for four musculoskeletal outcomes were carried out on these data. Each included analyses with multiple logistic regression (MLR) performed separately for women, men, and the total study population. The results from these gender-stratified and unstratified analyses were compared. In the unstratified MLR models, gender was significantly associated with musculoskeletal pain in the neck and lower extremities, but not with low-back pain. The gender-stratified MLR models identified significant associations between each specific musculoskeletal outcome and a variety of personal characteristics and physical and psychosocial workplace exposures for each gender. Most of the associations, if present for one gender, were also found in the total population. But several risk factors present for only one gender could be detected only in a stratified analysis, whereas the unstratified analysis added little information. Stratifying analyses by gender is necessary if a full range of associations between exposures and MSD is to be detected and understood.

Stratified exact tests for the weak causal null hypothesis in randomized trials with a binary outcome.

PubMed

Chiba, Yasutaka

2017-09-01

Fisher's exact test is commonly used to compare two groups when the outcome is binary in randomized trials. In the context of causal inference, this test explores the sharp causal null hypothesis (i.e. the causal effect of treatment is the same for all subjects), but not the weak causal null hypothesis (i.e. the causal risks are the same in the two groups). Therefore, in general, rejection of the null hypothesis by Fisher's exact test does not mean that the causal risk difference is not zero. Recently, Chiba (Journal of Biometrics and Biostatistics 2015; 6: 244) developed a new exact test for the weak causal null hypothesis when the outcome is binary in randomized trials; the new test is not based on any large sample theory and does not require any assumption. In this paper, we extend the new test; we create a version of the test applicable to a stratified analysis. The stratified exact test that we propose is general in nature and can be used in several approaches toward the estimation of treatment effects after adjusting for stratification factors. The stratified Fisher's exact test of Jung (Biometrical Journal 2014; 56: 129-140) tests the sharp causal null hypothesis. This test applies a crude estimator of the treatment effect and can be regarded as a special case of our proposed exact test. Our proposed stratified exact test can be straightforwardly extended to analysis of noninferiority trials and to construct the associated confidence interval. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Norcocaine and cocaethylene distribution patterns in hair samples from light, moderate, and heavy cocaine users

PubMed Central

Rossi, Riccardo; Aroni, Kyriaki; Gili, Alessio; Bacci, Mauro; Pascali, Vincenzo; Fucci, Nadia

2015-01-01

Even though hair analysis often seems to be the best choice for retrospective monitoring of cocaine intake, differentiating between incorporated cocaine and external contamination is widely debated. In this study we report results obtained in 90 hair samples from addicts. All samples were analyzed for cocaine, benzoylecgonine, norcocaine, cocaethylene, and tropococaine by gas chromatography‐mass spectrometry (GC‐MS) techniques coupled with direct immersion solid‐phase micro‐extraction. Cocaine concentrations were stratified into three classes of usage: light (0.5–3 ng/mg), moderate (3.1–10 ng/mg) and heavy (10.1–40 ng/mg). The Substance Abuse and Mental Health Services Administration cut‐off criteria for establishing active cocaine use were applied to the results. For all samples criteria were cocaine levels above 0.5 ng/mg (ranging from 1.63 to 39.29 ng/mg, mean 9.49 ng/mg), benzoylecgonine concentrations ≥ 0.05 ng/mg (ranging from 0.19 to 5.77 ng/mg, mean 1.40), and benzoylecgonine to cocaine % ratio ≥5% (from 6.43 to 26.09%). Norcocaine was present in 58.9% of samples (concentration range: 0.22–3.14 ng/mg) and was strongly predictive only of heavy cocaine use (sensitivity 100% for cocaine concentrations above 9.58 ng/mg). Twenty hair samples from moderate and heavy users tested positive for cocaethylene (concentration range: 0.22–1.98 ng/mg, mean 0.73 ng/mg). This study on hair samples with no chance of false positive cases highlights the very limited applications of testing minor cocaine metabolites for definitive proof of active cocaine consumption. © 2015 The Authors. Drug Testing and Analysis Published by John Wiley & Sons, Ltd. PMID:26621770

Norcocaine and cocaethylene distribution patterns in hair samples from light, moderate, and heavy cocaine users.

PubMed

Gambelunghe, Cristiana; Rossi, Riccardo; Aroni, Kyriaki; Gili, Alessio; Bacci, Mauro; Pascali, Vincenzo; Fucci, Nadia

2017-02-01

Even though hair analysis often seems to be the best choice for retrospective monitoring of cocaine intake, differentiating between incorporated cocaine and external contamination is widely debated. In this study we report results obtained in 90 hair samples from addicts. All samples were analyzed for cocaine, benzoylecgonine, norcocaine, cocaethylene, and tropococaine by gas chromatography-mass spectrometry (GC-MS) techniques coupled with direct immersion solid-phase micro-extraction. Cocaine concentrations were stratified into three classes of usage: light (0.5-3 ng/mg), moderate (3.1-10 ng/mg) and heavy (10.1-40 ng/mg). The Substance Abuse and Mental Health Services Administration cut-off criteria for establishing active cocaine use were applied to the results. For all samples criteria were cocaine levels above 0.5 ng/mg (ranging from 1.63 to 39.29 ng/mg, mean 9.49 ng/mg), benzoylecgonine concentrations ≥ 0.05 ng/mg (ranging from 0.19 to 5.77 ng/mg, mean 1.40), and benzoylecgonine to cocaine % ratio ≥5% (from 6.43 to 26.09%). Norcocaine was present in 58.9% of samples (concentration range: 0.22-3.14 ng/mg) and was strongly predictive only of heavy cocaine use (sensitivity 100% for cocaine concentrations above 9.58 ng/mg). Twenty hair samples from moderate and heavy users tested positive for cocaethylene (concentration range: 0.22-1.98 ng/mg, mean 0.73 ng/mg). This study on hair samples with no chance of false positive cases highlights the very limited applications of testing minor cocaine metabolites for definitive proof of active cocaine consumption. © 2015 The Authors. Drug Testing and Analysis Published by John Wiley & Sons, Ltd. © 2015 The Authors. Drug Testing and Analysis Published by John Wiley & Sons, Ltd.

An analysis of wilderness water in Kings Canyon, Sequoia, and Yosemite national parks for coliform and pathologic bacteria.

PubMed

Derlet, Robert W; Carlson, James R

2004-01-01

To determine the prevalence of coliform and potentially pathogenic bacteria in remote backcountry alpine lakes and streams of national parks in the Sierra Nevada mountains. Water was sampled at 55 predetermined lakes and streams that would stratify the risk, based on sites used by backpackers, sites used by pack animals, and uncontaminated wild areas. Sites were distributed among Kings Canyon (15), Sequoia (17), and Yosemite (23). Water was collected using Millipore bacterial samplers, which provided specific counts of coliform and other bacteria in each water sample and also served as a transport media from the wilderness to the laboratory. On return to the laboratory, bacteria were harvested from the samplers and subjected to specific identification and qualitative analysis using standard microbiology techniques for the analysis of water. Coliform bacteria were detected in 22 of the 55 sites. All of these sites were below areas used by backpackers or pack animals. Thirty-three sites were free of coliforms. These sites included both those used lightly by backpackers and those with no human or domestic animal use. All samples contained expected amounts of normal aquatic bacteria including Pseudomonas, Rahnella aquatilis, Serratia spp, and nonpathogenic species of Yersinia. Most sampling sites in these national parks are free of coliform or pathogenic organisms. Low levels of coliform bacteria are found in some bodies of water where the watershed has been affected by human or pack animal travel.

Aggregating pixel-level basal area predictions derived from LiDAR data to industrial forest stands in North-Central Idaho

Treesearch

Andrew T. Hudak; Jeffrey S. Evans; Nicholas L. Crookston; Michael J. Falkowski; Brant K. Steigers; Rob Taylor; Halli Hemingway

2008-01-01

Stand exams are the principal means by which timber companies monitor and manage their forested lands. Airborne LiDAR surveys sample forest stands at much finer spatial resolution and broader spatial extent than is practical on the ground. In this paper, we developed models that leverage spatially intensive and extensive LiDAR data and a stratified random sample of...

The Effect Of Age At Harvest On Bending And Tensile Properties Of Loblolly Pine From The Coastal Plain

Treesearch

Robert H. McAlister; Alexander Clark; Joseph R. Saucier

1997-01-01

The effect of rotation age on strength and stiffness of lumber produced from unthinned loblolly pine stands in the Coastal Plain of Georgia was examined. Six stands representing 22-, 28-, and 40-year-old roations were sampled. A stratified random sample of trees 8 to 16 inches in diameter at breast height was selected from each stand and processed into lumber....

Assessment of post-fire forest structural diversity using neighborhood parameter in the Sierra Madre Oriental, Mexico

Treesearch

Diana Yemilet Avila Flores; Marco Aurelio González Tagle; Javier Jiménez Pérez; Oscar Aguirre Calderón; Eduardo Treviño Garza

2013-01-01

The objective of this research was to characterize the spatial structure patterns of a Pinus hartwegii forest in the Sierra Madre Oriental, affected by a fire in 1998. Sampling was stratified by fire severity. A total of three fire severity classes (low, medium and high) were defined. Three sample plots of 40m x 40m were established for each...

Use of health insurance claim patterns to identify patients using nonsteroidal anti-inflammatory drugs for rheumatoid arthritis.

PubMed

Bernard, Marie-Agnès; Bénichou, Jacques; Blin, Patrick; Weill, Alain; Bégaud, Bernard; Abouelfath, Abdelilah; Moore, Nicholas; Fourrier-Réglat, Annie

2012-06-01

To determine healthcare claim patterns associated using nonsteroidal anti-inflammatory drugs (NSAIDs) for rheumatoid arthritis (RA). The CADEUS study randomly identified NSAID users within the French health insurance database. One-year claims data were extracted, and NSAID indication was obtained from prescribers. Logistic regression was used in a development sample to identify claim patterns predictive of RA and models applied to a validation sample. Analyses were stratified on the dispensation of immunosuppressive agents or specific antirheumatism treatment, and the area under the receiver operating characteristic curve was used to estimate discriminant power. NSAID indication was provided for 26,259 of the 45,217 patients included in the CADEUS cohort; it was RA for 956 patients. Two models were constructed using the development sample (n = 13,143), stratifying on the dispensation of an immunosuppressive agent or specific antirheumatism treatment. Discriminant power was high for both models (AUC > 0.80) and was not statistically different from that found when applied to the validation sample (n = 13,116). The models derived from this study may help to identify patients prescribed NSAIDs who are likely to have RA in claims databases without medical data such as treatment indication. Copyright © 2012 John Wiley & Sons, Ltd.

Study on the availability of physical infrastructure and manpower facilities in sub-centers of Chittoor district of Andhra Pradesh.

PubMed

Reddy, N Bayapa; Prabhu, G Ravi; Sai, T S R

2012-01-01

The sub-centers (SCs) are under constant criticism for their inability to deliver quality services due to the nonavailability of adequate infrastructure, manpower and supply of drugs.A cross-sectional study was conducted in Chittoor District of Andhra Pradesh to assess the availability of physical infrastructure and manpower in the SCs. A total of 34 SCs were selected by multistage and stratified random sampling technique. The data was statistically analyzed by using Microsoft Excel. The deficiency in the availability of health workers male and female were found to be 67.7% and 27.5%, respectively. The residential facility for health workers was available only in 26.4% SCs. Only 20.6% of SCs had stethoscope and B.P apparatus. The physical infrastructure and manpower availability at the SCs needs considerable improvement as per the Indian Public Health Standard (IPHS). Facilities to conduct the normal delivery and 24-hours emergency referral services need to be addressed at the earliest.

Local Kernel for Brains Classification in Schizophrenia

NASA Astrophysics Data System (ADS)

Castellani, U.; Rossato, E.; Murino, V.; Bellani, M.; Rambaldelli, G.; Tansella, M.; Brambilla, P.

In this paper a novel framework for brain classification is proposed in the context of mental health research. A learning by example method is introduced by combining local measurements with non linear Support Vector Machine. Instead of considering a voxel-by-voxel comparison between patients and controls, we focus on landmark points which are characterized by local region descriptors, namely Scale Invariance Feature Transform (SIFT). Then, matching is obtained by introducing the local kernel for which the samples are represented by unordered set of features. Moreover, a new weighting approach is proposed to take into account the discriminative relevance of the detected groups of features. Experiments have been performed including a set of 54 patients with schizophrenia and 54 normal controls on which region of interest (ROI) have been manually traced by experts. Preliminary results on Dorso-lateral PreFrontal Cortex (DLPFC) region are promising since up to 75% of successful classification rate has been obtained with this technique and the performance has improved up to 85% when the subjects have been stratified by sex.

Influence of marital and educational status on clients' psychosocial adjustment to HIV/AIDS in Calabar, Nigeria.

PubMed

Akpabio, Idongesit I; Uyanah, David A; Osuchukwu, Nelson C; Samson-Akpan, Patience E

2010-06-01

A comparative descriptive design and a stratified random sampling technique were adopted to study the influence of marital and educational status on the psychological, social, and spiritual adjustment of 280 respondents living with HIV/AIDS in two randomly selected clinics within Calabar, Nigeria. A 30 item questionnaire, with a content validity index of 0.92 and a Cronbach's alpha reliability coefficient of 0.94, was used for data collection, with due attention to ethical considerations. The findings showed that marital status had a significant influence on the respondents' psychological and social adjustment but not on their spiritual adjustment. Those that were married and those with higher educational qualifications had better psychological adjustment than those who had never married. The marital and educational status of clients should be considered when conducting education or counseling, making recommendations, or organizing support groups for living with HIV/AIDS. Furthermore, advocacy aimed at meeting the psychosocial needs of single and less-educated clients could enhance their psychosocial adjustment.

Bhutanese Students' Views of Nature of Science: a Case Study of Culturally Rich Country

NASA Astrophysics Data System (ADS)

Das, Pabi Maya; Faikhamta, Chatree; Punsuvon, Vittaya

2017-07-01

This study is aimed at exploring ninth-grade Bhutanese students' views of nature of science (NOS). A total of 389 students from middle secondary and higher secondary schools from the eastern, western, southern and central regions of Bhutan took part in this study. To generate a representative population, a stratified random sampling technique was used. An adopted and adapted version of the Students Understanding of Science and Scientific Inquiry (SUSSI) comprised Likert-type items, and open-ended questions were used as a research tool. Quantitative data were analysed using descriptive statistics, and the qualitative data were analysed and categorized into naïve, transitional and informed views. The results indicated that the majority of the Bhutanese students held naïve views on sociocultural embeddedness, scientific laws, scientific theories and science as a body of knowledge. The study has an implication for curriculum developers and teaching professionals, particularly in culturally rich countries, that explicit instruction of NOS should be reframed based on students' cultural backgrounds and their indigenous knowledge.

Predictors of adolescents' mental health problems in Saudi Arabia: findings from the Jeeluna® national study.

PubMed

Abou Abbas, Oraynab; AlBuhairan, Fadia

2017-01-01

Depression and anxiety among adolescents require further attention as they have profound harmful implications on several aspects of adolescents' wellbeing and can be associated with life threatening risk behaviors such as suicide. To examine the underlying risk factors for feeling so sad or hopeless and for feeling worried among adolescents in Saudi Arabia. Data from Jeeluna ® national survey was used. A cross-sectional, multi-stage, stratified, cluster random sampling technique was applied among a sample of students aged 10-19 years attending intermediate and secondary schools in Saudi Arabia. A self-administered questionnaire assessing several domains, including feeling so sad or hopeless and worried, was used to collect data. Logistic regression models were fitted to determine the different factors associated with mental health. A sample of 12,121 students was included in this study. Feeling so sad or hopeless and feeling worried were significantly more prevalent among females and older adolescents ( p  < 0.0001). The results showed that poor relationship with parents, negative body image, and chronic illness to be significantly associated with feeling so sad or hopeless and worried. Symptoms suggestive of mental health problems among adolescents in Saudi Arabia are prevalent and deserve special attention. Adopting effective strategies, including regular screening and intervention programs are highly needed to better address, detect, and control early signs of these problems.

Bacterial Contamination and Disinfection Status of Laryngoscopes Stored in Emergency Crash Carts

PubMed Central

Lee, Jung Won; Shin, Hee Bong; Lee, In Kyung

2017-01-01

Objectives To identify bacterial contamination rates of laryngoscope blades and handles stored in emergency crash carts by hospital and area according to the frequency of intubation attempts. Methods One hundred forty-eight handles and 71 blades deemed ready for patient use from two tertiary hospitals were sampled with sterile swabs using a standardized rolling technique. Samples were considered negative (not contaminated) if no colonies were present on the blood agar plate after an 18-hour incubation period. Samples were stratified by hospital and according to the frequency of intubation attempts (10 attempts per year) using the χ2-test and Fisher exact test. Results One or more species of bacteria were isolated from 4 (5.6%) handle tops, 20 (28.2%) handles with knurled surfaces, and 27 (18.2%) blades. No significant differences were found in microbial contamination levels on the handle tops and blades between the two hospitals and two areas according to the frequency of intubation attempts. However, significant differences were found between the two hospitals and two areas in the level of microbial contamination on the handles with knurled surfaces (p<0.05). Conclusions Protocols and policies must be reviewed to standardize procedures to clean and disinfect laryngoscope blades and handles; handles should be re-designed to eliminate points of contact with the blade; and single-use, one-piece laryngoscopes should be introduced. PMID:28605891

A software suite for the generation and comparison of peptide arrays from sets of data collected by liquid chromatography-mass spectrometry.

PubMed

Li, Xiao-jun; Yi, Eugene C; Kemp, Christopher J; Zhang, Hui; Aebersold, Ruedi

2005-09-01

There is an increasing interest in the quantitative proteomic measurement of the protein contents of substantially similar biological samples, e.g. for the analysis of cellular response to perturbations over time or for the discovery of protein biomarkers from clinical samples. Technical limitations of current proteomic platforms such as limited reproducibility and low throughput make this a challenging task. A new LC-MS-based platform is able to generate complex peptide patterns from the analysis of proteolyzed protein samples at high throughput and represents a promising approach for quantitative proteomics. A crucial component of the LC-MS approach is the accurate evaluation of the abundance of detected peptides over many samples and the identification of peptide features that can stratify samples with respect to their genetic, physiological, or environmental origins. We present here a new software suite, SpecArray, that generates a peptide versus sample array from a set of LC-MS data. A peptide array stores the relative abundance of thousands of peptide features in many samples and is in a format identical to that of a gene expression microarray. A peptide array can be subjected to an unsupervised clustering analysis to stratify samples or to a discriminant analysis to identify discriminatory peptide features. We applied the SpecArray to analyze two sets of LC-MS data: one was from four repeat LC-MS analyses of the same glycopeptide sample, and another was from LC-MS analysis of serum samples of five male and five female mice. We demonstrate through these two study cases that the SpecArray software suite can serve as an effective software platform in the LC-MS approach for quantitative proteomics.

DESIGNING MONITORING AND ASSESSMENT STRATEGIES TO INCLUDE NEARSHORE ECOSYSTEMS OF THE GREAT LAKES

EPA Science Inventory

An expectation for monitoring and assessment of very large aquatic systems is that we can develop a strategy that recognizes and reports on ecologically-important subareas using spatially-stratified, probabilistic sampling designs. Ongoing efforts monitor the main-body, offshore ...

Education Needs of Michigan Farmers

ERIC Educational Resources Information Center

Suvedi, Murari; Jeong, Eunseong; Coombs, John

2010-01-01

In 2008 MSU Extension evaluated their program to identify the major areas of educational need for Michigan farmers and agribusiness operators. Surveys were mailed to a stratified random sample from Michigan Agricultural Statistics Service records of dairy, livestock, swine, cash crops, fruit, vegetable, and nursery/greenhouse producers. Findings…

New Mathematical Strategy Using Branch and Bound Method

NASA Astrophysics Data System (ADS)

Tarray, Tanveer Ahmad; Bhat, Muzafar Rasool

In this paper, the problem of optimal allocation in stratified random sampling is used in the presence of nonresponse. The problem is formulated as a nonlinear programming problem (NLPP) and is solved using Branch and Bound method. Also the results are formulated through LINGO.

Assessment of powder blend uniformity: Comparison of real-time NIR blend monitoring with stratified sampling in combination with HPLC and at-line NIR Chemical Imaging.

PubMed

Bakri, Barbara; Weimer, Marco; Hauck, Gerrit; Reich, Gabriele

2015-11-01

Scope of the study was (1) to develop a lean quantitative calibration for real-time near-infrared (NIR) blend monitoring, which meets the requirements in early development of pharmaceutical products and (2) to compare the prediction performance of this approach with the results obtained from stratified sampling using a sample thief in combination with off-line high pressure liquid chromatography (HPLC) and at-line near-infrared chemical imaging (NIRCI). Tablets were manufactured from powder blends and analyzed with NIRCI and HPLC to verify the real-time results. The model formulation contained 25% w/w naproxen as a cohesive active pharmaceutical ingredient (API), microcrystalline cellulose and croscarmellose sodium as cohesive excipients and free-flowing mannitol. Five in-line NIR calibration approaches, all using the spectra from the end of the blending process as reference for PLS modeling, were compared in terms of selectivity, precision, prediction accuracy and robustness. High selectivity could be achieved with a "reduced" approach i.e. API and time saving approach (35% reduction of API amount) based on six concentration levels of the API with three levels realized by three independent powder blends and the additional levels obtained by simply increasing the API concentration in these blends. Accuracy and robustness were further improved by combining this calibration set with a second independent data set comprising different excipient concentrations and reflecting different environmental conditions. The combined calibration model was used to monitor the blending process of independent batches. For this model formulation the target concentration of the API could be achieved within 3 min indicating a short blending time. The in-line NIR approach was verified by stratified sampling HPLC and NIRCI results. All three methods revealed comparable results regarding blend end point determination. Differences in both mean API concentration and RSD values could be attributed to differences in effective sample size and thief sampling errors. This conclusion was supported by HPLC and NIRCI analysis of tablets manufactured from powder blends after different blending times. In summary, the study clearly demonstrates the ability to develop efficient and robust quantitative calibrations for real-time NIR powder blend monitoring with a reduced set of powder blends while avoiding any bias caused by physical sampling. Copyright © 2015 Elsevier B.V. All rights reserved.

DIAGNOSIS OF ENDOCRINE DISEASE: High-yield thyroid fine-needle aspiration cytology: an update focused on ancillary techniques improving its accuracy.

PubMed

Bongiovanni, M; Trimboli, P; Rossi, E D; Fadda, G; Nobile, A; Giovanella, L

2016-02-01

Thyroid fine-needle aspiration (FNA) cytology is a fast growing field. One of the most developing areas is represented by molecular tests applied to cytological material. Patients that could benefit the most from these tests are those that have been diagnosed as 'indeterminate' on FNA. They could be better stratified in terms of malignancy risk and thus oriented with more confidence to the appropriate management. Taking in to consideration the need to improve and keep high the yield of thyroid FNA, professionals from various fields (i.e. molecular biologists, endocrinologists, nuclear medicine physicians and radiologists) are refining and fine-tuning their diagnostic instruments. In particular, all these developments aim at increasing the negative predictive value of FNA to improve the selection of patients for diagnostic surgery. These advances involve terminology, the application of next-generation sequencing to thyroid FNA, the use of immunocyto- and histo-chemistry, the development of new sampling techniques and the increasing use of nuclear medicine as well as molecular imaging in the management of patients with a thyroid nodule. Herein, we review the recent advances in thyroid FNA cytology that could be of interest to the 'thyroid-care' community, with particular focus on the indeterminate diagnostic category. © 2016 European Society of Endocrinology.

Free Thermal Convection Inside a Stably Stratified FLUID:A Study by Means of Three Dimensional Particle Tracking Velocimetry

NASA Astrophysics Data System (ADS)

Cenedese, A.; Dore, V.; Moroni, M.

2009-05-01

Free thermal convection refers to the motion of vertical turbulent plumes or domes, which can occur when, an initially in-rest stratified fluid, is submitted to buoyancy forces, caused by a permanent perturbation associated to a heat transfer mechanism. When a fluid, in equilibrium, is stably stratified the external forcing can produce an unstable configuration ensuing the increasing in amplitude of internal waves, and, if it has strength enough, it can definitely erode the stratification, involving an increasing thickness of fluid volume. The entrainment phenomenon justifies the penetrative feature of convection and causes the growth of a convective boundary layer of well mixed fluid (Convective Mixing Layer) against the adjacent stable stratified layer. The non-steady phenomenon of penetrative convection in a stably stratified fluid has been reproduced in laboratory employing a tank filled with water and subjected to heating from below. The goal in the experiment is predicting the convective boundary layer growth as a function of initial and boundary conditions and describing the fate of a tracer dissolved in the fluid phase. The motivations of the research are mostly related to its connections to environmental topics. In nature the dynamics of penetrative convection influences the transport and mixing features of stratified fluids, playing a fundamental role in characterizing and forecasting the distribution of chemical species, with implication for water or air quality in the upper oceans and lakes or in the lower troposphere. When studying turbulent convective phenomenon, dispersion is mostly due to transport by large organized structures while molecular diffusion can be neglected. The knowledge of the horizontal and vertical extension of the structures dominating the flow field appears to be mandatory. In order to better understanding and likely describing the evolution of turbulent structures inside the convective layer, a fully three dimensional experimental technique is required. The equipment employed is suitable for simultaneously providing temperatures inside the domain through thermocouples and Lagrangian particle trajectories obtained by using a 3D-PTV technique. The combined use of a vertical array of thermocouples and 3D-PTV allows, simultaneously, profiling temperature and the 3D velocity components. A properly calibrated stereoscopic system of three monochrome 25 fps CCD cameras has been employed. The combination of image and object space based information is applied to establish the spatio-temporal correspondences between particle position of consecutive time steps, resulting in the reconstruction of 3D trajectories. The vertical dimension of convective structures is associated to the mixing layer height, detected both employing temperature data and statistics of the velocity field. On the other hand, the spatial correlation of the velocity field, providing the plume horizontal dimension, allows the horizontal extension of the mixing region to be determined. This information coupled to the knowledge of the mixing layer height allows the spatial extension of the convective region to be fully described.

Crystalline Stratification in Semiconducting Polymer Thin Film Quantified by Grazing Incidence X-ray Scattering

NASA Astrophysics Data System (ADS)

Gann, Eliot; Caironi, Mario; Noh, Yong-Young; Kim, Yun-Hi; McNeill, Christopher R.

The depth dependence of crystalline structure within thin films is critical for many technological applications, but has been impossible to measure directly using common techniques. In this work, by monitoring diffraction peak intensity and location and utilizing the highly angle-dependent waveguiding effects of X-rays near grazing incidence we quantitatively measure the thickness, roughness and orientation of stratified crystalline layers within thin films of a high-performance semiconducting polymer. In particular, this diffractive X-ray waveguiding reveals a self-organized 5-nm-thick crystalline surface layer with crystalline orientation orthogonal to the underlying 65-nm-thick layer. While demonstrated for an organic semiconductor film, this approach is applicable to any thin film material system where stratified crystalline structure and orientation can influence important interfacial processes such as charge injection and field-effect transport.

Colonization of the Stratified Squamous Epithelium of the Nonsecreting Area of Horse Stomach by Lactobacilli

PubMed Central

Yuki, Norikatsu; Shimazaki, Tomoko; Kushiro, Akira; Watanabe, Koichi; Uchida, Kazumi; Yuyama, Teruhiko; Morotomi, Masami

2000-01-01

Selective adhesion to only certain epithelia is particularly common among the bacterial members of the indigenous microflora of mammals. We have found that the stratified squamous epithelium of the nonsecreting area of horse stomach is colonized by gram-positive rods. The microscopic features of a dense layer of these bacteria on the epithelium were found to be similar to those reported in mice, rats, and swine. Adhering microorganisms were isolated and identified as Lactobacillus salivarius, L. crispatus, L. reuteri, and L. agilis by DNA-DNA hybridization and 16S rRNA gene sequencing techniques. These lactobacilli associated with the horse, except for L. reuteri, were found to adhere to horse epithelial cells in vitro but not to those of rats. A symbiotic relationship of these lactobacilli with the horse is suggested. PMID:11055960

The systematic component of phylogenetic error as a function of taxonomic sampling under parsimony.

PubMed

Debry, Ronald W

2005-06-01

The effect of taxonomic sampling on phylogenetic accuracy under parsimony is examined by simulating nucleotide sequence evolution. Random error is minimized by using very large numbers of simulated characters. This allows estimation of the consistency behavior of parsimony, even for trees with up to 100 taxa. Data were simulated on 8 distinct 100-taxon model trees and analyzed as stratified subsets containing either 25 or 50 taxa, in addition to the full 100-taxon data set. Overall accuracy decreased in a majority of cases when taxa were added. However, the magnitude of change in the cases in which accuracy increased was larger than the magnitude of change in the cases in which accuracy decreased, so, on average, overall accuracy increased as more taxa were included. A stratified sampling scheme was used to assess accuracy for an initial subsample of 25 taxa. The 25-taxon analyses were compared to 50- and 100-taxon analyses that were pruned to include only the original 25 taxa. On average, accuracy for the 25 taxa was improved by taxon addition, but there was considerable variation in the degree of improvement among the model trees and across different rates of substitution.

The role of perceived barriers and objectively measured physical activity in adults aged 65-100.

PubMed

Gellert, Paul; Witham, Miles D; Crombie, Iain K; Donnan, Peter T; McMurdo, Marion E T; Sniehotta, Falko F

2015-05-01

to test the predictive utility of perceived barriers to objectively measured physical activity levels in a stratified sample of older adults when accounting for social-cognitive determinants proposed by the Theory of Planned Behaviour (TPB), and economic and demographic factors. data were analysed from the Physical Activity Cohort Scotland survey, a representative and stratified (65-80 and 80+ years; deprived and affluent) sample of 584 community-dwelling older people, resident in Tayside, Scotland. Physical activity was measured objectively by accelerometry. perceived barriers clustered around the areas of poor health, lack of interest, lack of safety and lack of access. Perceived poor health and lack of interest, but not lack of access or concerns about personal safety, predicted physical activity after controlling for demographic, economic and TPB variables. perceived person-related barriers (poor health and lack of interest) seem to be more strongly associated with physical activity levels than perceived environmental barriers (safety and access) in a large sample of older adults. Perceived barriers are modifiable and may be a target for future interventions. © The Author 2015. Published by Oxford University Press on behalf of the British Geriatrics Society. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Benford's Law based detection of latent fingerprint forgeries on the example of artificial sweat printed fingerprints captured by confocal laser scanning microscopes

NASA Astrophysics Data System (ADS)

Hildebrandt, Mario; Dittmann, Jana

2015-03-01

The possibility of forging latent fingerprints at crime scenes is known for a long time. Ever since it has been stated that an expert is capable of recognizing the presence of multiple identical latent prints as an indicator towards forgeries. With the possibility of printing fingerprint patterns to arbitrary surfaces using affordable ink- jet printers equipped with artificial sweat, it is rather simple to create a multitude of fingerprints with slight variations to avoid raising any suspicion. Such artificially printed fingerprints are often hard to detect during the analysis procedure. Moreover, the visibility of particular detection properties might be decreased depending on the utilized enhancement and acquisition technique. In previous work primarily such detection properties are used in combination with non-destructive high resolution sensory and pattern recognition techniques to detect fingerprint forgeries. In this paper we apply Benford's Law in the spatial domain to differentiate between real latent fingerprints and printed fingerprints. This technique has been successfully applied in media forensics to detect image manipulations. We use the differences between Benford's Law and the distribution of the most significant digit of the intensity and topography data from a confocal laser scanning microscope as features for a pattern recognition based detection of printed fingerprints. Our evaluation based on 3000 printed and 3000 latent print samples shows a very good detection performance of up to 98.85% using WEKA's Bagging classifier in a 10-fold stratified cross-validation.

Phase II Trials for Heterogeneous Patient Populations with a Time-to-Event Endpoint.

PubMed

Jung, Sin-Ho

2017-07-01

In this paper, we consider a single-arm phase II trial with a time-to-event end-point. We assume that the study population has multiple subpopulations with different prognosis, but the study treatment is expected to be similarly efficacious across the subpopulations. We review a stratified one-sample log-rank test and present its sample size calculation method under some practical design settings. Our sample size method requires specification of the prevalence of subpopulations. We observe that the power of the resulting sample size is not very sensitive to misspecification of the prevalence.

Computers in Public Education Study.

ERIC Educational Resources Information Center

HBJ Enterprises, Highland Park, NJ.

This survey conducted for the National Institute of Education reports the use of computers in U.S. public schools in the areas of instructional computing, student accounting, management of educational resources, research, guidance, testing, and library applications. From a stratified random sample of 1800 schools in varying geographic areas and…

Self-identity Changes and English Learning among Chinese Undergraduates.

ERIC Educational Resources Information Center

Yihong, Gao; Ying, Cheng; Yuan, Zhao; Yan, Zhou

2005-01-01

This quantitative study investigated Chinese college students' self-identity changes associated with English learning. The subjects were 2,278 undergraduates from 30 universities, obtained from a stratified sampling. Based on existing literature of bilinguals identities, the self-designed questionnaire defined six categories of self-identity…

Near-infrared spectroscopy used to predict soybean seed germination and vigor

USDA-ARS?s Scientific Manuscript database

The potential of using near-infrared (NIR) spectroscopy for differentiating levels in germination, vigor, and electrical conductivity of soybean seeds was investigated. For the 243 spectral data collected using the Perten DA7200, stratified sampling was used to obtain three calibration sets consisti...

Heredity and Environment in the Development of Intelligence

ERIC Educational Resources Information Center

Migliorino, Giuseppe

1974-01-01

Intelligence tests were administered to a stratified sample of 4058 school children from Palermo, Sicily. I.Q. scores were found to be positively correlated with socioeconomic status and negatively related to family size. As birth order increased, mental development decreased. Implications for future research were discussed. (EH)

Factors Affecting Retirement Attitude among Elementary School Teachers

ERIC Educational Resources Information Center

Hsu, Wan-Chen; Chiang, Chia-Hsun; Chuang, Hsueh-Hua

2015-01-01

This study investigated the relationships of teacher efficacy, perceived organizational control, and the teacher-student age gap with teachers' retirement attitudes. Stratified random sampling was adopted to collect survey responses. A total of 498 valid surveys from 33 elementary schools were collected. Correlational analyses revealed significant…

Singaporean Kindergartners' Phonological Awareness and English Writing Skills

ERIC Educational Resources Information Center

Dixon, L. Quentin

2011-01-01

This article describes the phonological awareness and English writing skills among a sample of 297 Singaporean kindergarten children, stratified by ethnicity (Chinese, Malay, and Indian), and examines the relationship between oral language and writing skills in this multilingual population. Overall, Singaporean kindergartners, nearly all of whom…

Multi-Sensory Intervention Observational Research

ERIC Educational Resources Information Center

Thompson, Carla J.

2011-01-01

An observational research study based on sensory integration theory was conducted to examine the observed impact of student selected multi-sensory experiences within a multi-sensory intervention center relative to the sustained focus levels of students with special needs. A stratified random sample of 50 students with severe developmental…

Mother Knows Best? Inhibitory Maternal Gatekeeping, Psychological Control, and the Mother-Adolescent Relationship

ERIC Educational Resources Information Center

Holmes, Erin Kramer; Dunn, KayLee C.; Harper, James; Dyer, W. Justin; Day, Randal D.

2013-01-01

We used structural equation modeling to explore associations between inhibitory maternal gatekeeping attitudes, reports of inhibitory maternal gatekeeping behaviors, maternal psychological control, observed mother-adolescent warmth, and adolescent reports of maternal involvement. Our random stratified sample consisted of 315 mothers and their…

Teachers' Perceptions of the Relevance and Usefulness of Professional Development

ERIC Educational Resources Information Center

Shoemaker, Susan F.

2013-01-01

The purpose of this qualitative, phenomenological study was to investigate, through interviews, secondary teachers' perceptions of the level of the value, applicability, and implementation of skills learned within professional development offerings in the targeted school district. Non-probability, stratified, purposeful sampling was utilized to…

Stratifying empiric risk of schizophrenia among first degree relatives using multiple predictors in two independent Indian samples.

PubMed

Bhatia, Triptish; Gettig, Elizabeth A; Gottesman, Irving I; Berliner, Jonathan; Mishra, N N; Nimgaonkar, Vishwajit L; Deshpande, Smita N

2016-12-01

Schizophrenia (SZ) has an estimated heritability of 64-88%, with the higher values based on twin studies. Conventionally, family history of psychosis is the best individual-level predictor of risk, but reliable risk estimates are unavailable for Indian populations. Genetic, environmental, and epigenetic factors are equally important and should be considered when predicting risk in 'at risk' individuals. To estimate risk based on an Indian schizophrenia participant's family history combined with selected demographic factors. To incorporate variables in addition to family history, and to stratify risk, we constructed a regression equation that included demographic variables in addition to family history. The equation was tested in two independent Indian samples: (i) an initial sample of SZ participants (N=128) with one sibling or offspring; (ii) a second, independent sample consisting of multiply affected families (N=138 families, with two or more sibs/offspring affected with SZ). The overall estimated risk was 4.31±0.27 (mean±standard deviation). There were 19 (14.8%) individuals in the high risk group, 75 (58.6%) in the moderate risk and 34 (26.6%) in the above average risk (in Sample A). In the validation sample, risks were distributed as: high (45%), moderate (38%) and above average (17%). Consistent risk estimates were obtained from both samples using the regression equation. Familial risk can be combined with demographic factors to estimate risk for SZ in India. If replicated, the proposed stratification of risk may be easier and more realistic for family members. Copyright © 2016. Published by Elsevier B.V.

DoD Met Most Requirements of the Improper Payments Elimination and Recovery Act in FY 2014, but Improper Payment Estimates Were Unreliable

DTIC Science & Technology

2015-05-12

Deficiencies That Affect the Reliability of Estimates ________________________________________6 Statistical Precision Could Be Improved... statistical precision of improper payments estimates in seven of the DoD payment programs through the use of stratified sample designs. DoD improper...payments not subject to sampling, which made the results statistically invalid. We made a recommendation to correct this problem in a previous report;4

Initial response of soil carbon and nitrogen to harvest intensity and competing vegetation control in douglas-fir (Pseudotsuga menziesii) plantations of the Pacific Northwest

Treesearch

Robert A. Slesak; Stephen H. Schoenholtz; Timothy B. Harrington; Nathan A. Meehan

2011-01-01

We assessed the effect of harvest type (bole-only or whole-tree) and vegetation control treatments (initial or annual application of herbicide) on soil C and N at two contrasting sites in the Pacific Northwest. Pretreatment (2003) and posttreatment (2005) soil samples were collected by depth to 60 cm, and a stratified sampling approach based on four surface conditions...

Tumour vasculature immaturity, oxidative damage and systemic inflammation stratify survival of colorectal cancer patients on bevacizumab treatment

PubMed Central

Martin, Petra; Biniecka, Monika; Ó'Meachair, Shane; Maguire, Aoife; Tosetto, Miriam; Nolan, Blathnaid; Hyland, John; Sheahan, Kieran; O'Donoghue, Diarmuid; Mulcahy, Hugh; Fennelly, David; O'Sullivan, Jacintha

2018-01-01

Despite treatment of patients with metastatic colorectal cancer (mCRC) with bevacizumab plus chemotherapy, response rates are modest and there are no biomarkers available that will predict response. The aim of this study was to assess if markers associated with three interconnected cancer-associated biological processes, specifically angiogenesis, inflammation and oxidative damage, could stratify the survival outcome of this cohort. Levels of angiogenesis, inflammation and oxidative damage markers were assessed in pre-bevacizumab resected tumour and serum samples of mCRC patients by dual immunofluorescence, immunohistochemistry and ELISA. This study identified that specific markers of angiogenesis, inflammation and oxidative damage stratify survival of patients on this anti-angiogenic treatment. Biomarkers of immature tumour vasculature (% IMM, p=0.026, n=80), high levels of oxidative damage in the tumour epithelium (intensity of 8-oxo-dG in nuclear and cytoplasmic compartments, p=0.042 and 0.038 respectively, n=75) and lower systemic pro-inflammatory cytokines (IL6 and IL8, p=0.053 and 0.049 respectively, n=61) significantly stratify with median overall survival (OS). In summary, screening for a panel of biomarkers for high levels of immature tumour vasculature, high levels of oxidative DNA damage and low levels of systemic pro-inflammatory cytokines may be beneficial in predicting enhanced survival outcome following bevacizumab treatment for mCRC. PMID:29535825

Contemporary carotid imaging: from degree of stenosis to plaque vulnerability.

PubMed

Brinjikji, Waleed; Huston, John; Rabinstein, Alejandro A; Kim, Gyeong-Moon; Lerman, Amir; Lanzino, Giuseppe

2016-01-01

Carotid artery stenosis is a well-established risk factor of ischemic stroke, contributing to up to 10%-20% of strokes or transient ischemic attacks. Many clinical trials over the last 20 years have used measurements of carotid artery stenosis as a means to risk stratify patients. However, with improvements in vascular imaging techniques such as CT angiography and MR angiography, ultrasonography, and PET/CT, it is now possible to risk stratify patients, not just on the degree of carotid artery stenosis but also on how vulnerable the plaque is to rupture, resulting in ischemic stroke. These imaging techniques are ushering in an emerging paradigm shift that allows for risk stratifications based on the presence of imaging features such as intraplaque hemorrhage (IPH), plaque ulceration, plaque neovascularity, fibrous cap thickness, and presence of a lipid-rich necrotic core (LRNC). It is important for the neurosurgeon to be aware of these new imaging techniques that allow for improved patient risk stratification and outcomes. For example, a patient with a low-grade stenosis but an ulcerated plaque may benefit more from a revascularization procedure than a patient with a stable 70% asymptomatic stenosis with a thick fibrous cap. This review summarizes the current state-of-the-art advances in carotid plaque imaging. Currently, MRI is the gold standard in carotid plaque imaging, with its high resolution and high sensitivity for identifying IPH, ulceration, LRNC, and inflammation. However, MRI is limited due to time constraints. CT also allows for high-resolution imaging and can accurately detect ulceration and calcification, but cannot reliably differentiate LRNC from IPH. PET/CT is an effective technique to identify active inflammation within the plaque, but it does not allow for assessment of anatomy, ulceration, IPH, or LRNC. Ultrasonography, with the aid of contrast enhancement, is a cost-effective technique to assess plaque morphology and characteristics, but it is limited in sensitivity and specificity for detecting LRNC, plaque hemorrhage, and ulceration compared with MRI. Also summarized is how these advanced imaging techniques are being used in clinical practice to risk stratify patients with low- and high-grade carotid artery stenosis. For example, identification of IPH on MRI in patients with low-grade carotid artery stenosis is a risk factor for failure of medical therapy, and studies have shown that such patients may fair better with carotid endarterectomy (CEA). MR plaque imaging has also been found to be useful in identifying revascularization candidates who would be better candidates for CEA than carotid artery stenting (CAS), as high intraplaque signal on time of flight imaging is associated with vulnerable plaque and increased rates of adverse events in patients undergoing CAS but not CEA.

Field Testing New Plot Designs and Methods for Determining Hydrophytic Vegetation during Wetland Delineations in the United States

DTIC Science & Technology

2014-03-01

Trees and woody vines are sampled in large plots with 9 m (30 ft) radii. Saplings, shrubs , and herbs are sampled in nested smaller plots with 2 m (5 ft... woody vines in 9 m (30 ft) radius plots and saplings, shrubs , and herbaceous species in 2 m (5 ft) radius plots. In herbaceous meadows, only the 2 m (5...suggests stratifying vegetation by growth forms of trees, shrubs , herbs, and vines and sampling plant communities by using nested circular plots

Relationships of the phase velocity with the microarchitectural parameters in bovine trabecular bone in vitro: Application of a stratified model

NASA Astrophysics Data System (ADS)

Lee, Kang Il

2012-08-01

The present study aims to provide insight into the relationships of the phase velocity with the microarchitectural parameters in bovine trabecular bone in vitro. The frequency-dependent phase velocity was measured in 22 bovine femoral trabecular bone samples by using a pair of transducers with a diameter of 25.4 mm and a center frequency of 0.5 MHz. The phase velocity exhibited positive correlation coefficients of 0.48 and 0.32 with the ratio of bone volume to total volume and the trabecular thickness, respectively, but a negative correlation coefficient of -0.62 with the trabecular separation. The best univariate predictor of the phase velocity was the trabecular separation, yielding an adjusted squared correlation coefficient of 0.36. The multivariate regression models yielded adjusted squared correlation coefficients of 0.21-0.36. The theoretical phase velocity predicted by using a stratified model for wave propagation in periodically stratified media consisting of alternating parallel solid-fluid layers showed reasonable agreements with the experimental measurements.

Evaluation of a mark-recapture method for estimating mortality and migration rates of stratified populations

USGS Publications Warehouse

Dorazio, R.M.; Rago, P.J.

1991-01-01

We simulated mark–recapture experiments to evaluate a method for estimating fishing mortality and migration rates of populations stratified at release and recovery. When fish released in two or more strata were recovered from different recapture strata in nearly the same proportions, conditional recapture probabilities were estimated outside the [0, 1] interval. The maximum likelihood estimates tended to be biased and imprecise when the patterns of recaptures produced extremely "flat" likelihood surfaces. Absence of bias was not guaranteed, however, in experiments where recapture rates could be estimated within the [0, 1] interval. Inadequate numbers of tag releases and recoveries also produced biased estimates, although the bias was easily detected by the high sampling variability of the estimates. A stratified tag–recapture experiment with sockeye salmon (Oncorhynchus nerka) was used to demonstrate procedures for analyzing data that produce biased estimates of recapture probabilities. An estimator was derived to examine the sensitivity of recapture rate estimates to assumed differences in natural and tagging mortality, tag loss, and incomplete reporting of tag recoveries.

Geohydrology and water quality of the stratified-drift aquifers in Upper Buttermilk Creek and Danby Creek Valleys, Town of Danby, Tompkins County, New York

USGS Publications Warehouse

Miller, Todd S.

2015-11-20

During 2007–10, groundwater samples were collected from 13 wells including 7 wells that are completed in the confined sand and gravel aquifers, 1 well that is completed in the unconfined aquifer, and 5 wells that are completed in the bedrock aquifers. Calcium dominates the cation composition and bicarbonate dominates the anion composition in most groundwater. Water quality in the study area generally meets state and Federal drinking-water standards but concentrations of some constituents exceeded the standards. The standards that were exceeded include sodium (3 samples), dissolved solids (1 sample), iron (3 samples), manganese (8 samples), and arsenic (1 sample).

A Comparison of Item Selection Techniques and Exposure Control Mechanisms in CATs Using the Generalized Partial Credit Model.

ERIC Educational Resources Information Center

Pastor, Dena A.; Dodd, Barbara G.; Chang, Hua-Hua

2002-01-01

Studied the impact of using five different exposure control algorithms in two sizes of item pool calibrated using the generalized partial credit model. Simulation results show that the a-stratified design, in comparison to a no-exposure control condition, could be used to reduce item exposure and overlap and increase pool use, while degrading…

Osteochondral allograft.

PubMed

Torrie, Arissa M; Kesler, William W; Elkin, Joshua; Gallo, Robert A

2015-12-01

Over the past decade, osteochondral allograft transplantation has soared in popularity. Advances in storage techniques have demonstrated improved chondrocyte viability at longer intervals and allowed for potential of increased graft availability. Recent studies have stratified outcomes according to location and etiology of the chondral or osteochondral defect. Unipolar lesions generally have favorable outcomes with promising 10-year survival rates. Though those undergoing osteochondral allograft transplantation often require reoperation, patient satisfaction remains high.

Psychological Distress and Related Factors in Female College Students

ERIC Educational Resources Information Center

Vazquez, Fernando L.; Otero, Patricia; Diaz, Olga

2012-01-01

Objective: This study assessed the psychological distress in Spanish college women and analyzed it in relation to sociodemographic and academic factors. Participants and Methods: The authors selected a stratified random sampling of 1,043 college women (average age of 22.2 years). Sociodemographic and academic information were collected, and…

75 FR 71439 - Agency Information Collection Activities: Announcement of Board Approval Under Delegated...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-11-23

... the extension for three years, with revision, of the following report: Report title: Domestic Finance.... Reporters: Domestic finance companies and mortgage companies. Estimated annual reporting hours: 350 hours... calendar day of the month from a stratified sample of finance companies. Each monthly report collects...

Affluence and Equality in Nonmetropolitan American, 1950-1970.

ERIC Educational Resources Information Center

Beck, E. M.; Bianchi, S.

Utilizing census data on a stratified sample of 276 U.S. countries, the relationships between economic development and the levels of affluence and inequality in rural America (1950-70) were investigated via development of a macro-level affluence/inequality model. Variables examined were: demographic and social characteristics; income…

Physical Activity among Older People Living Alone in Shanghai, China

ERIC Educational Resources Information Center

Chen, Yu; While, Alison E; Hicks, Allan

2015-01-01

Objective: To investigate physical activity among older people living alone in Shanghai, People's Republic of China, and key factors contributing to their physical activity. Methods: A cross-sectional questionnaire survey was administered in nine communities in Shanghai, using a stratified random cluster sample: 521 community-dwelling older people…

Trends in Financial Indicators of Colleges and Universities.

ERIC Educational Resources Information Center

Gomberg, Irene L.; Atelsek, Frank J.

A survey conducted by the Higher Education Panel sought trends in various items of information about the financial condition of colleges and universities. A stratified sample of 760 insitutions was used, excluding major research universities. Information was requested on basic finance data, dormitory occupancy rates, occurrence of institutional…

Determinants of Teachers' Attitudes towards E- Learning in Tanzanian Higher Learning Institutions

ERIC Educational Resources Information Center

Kisanga, Dalton H.

2016-01-01

This survey research study presents the findings on determinants of teachers' attitudes towards e-learning in Tanzanian higher learning institutions. The study involved 258 teachers from 4 higher learning institutions obtained through stratified, simple random sampling. Questionnaires and documentary review were used in data collection. Data were…

Abundance and population characteristics of Northern Spotted Owls (Strix occidentalis caurina) in Olympic National Park, Washington

Treesearch

D. Erran Seaman

1997-01-01

We monitored the threatened Northern Spotted Owl (Strix occidentalis caurina) in Olympic National Park from 1992 through 1996. We used a stratified random sampling scheme to survey 35 plots totaling 236 km?, approximately 10 percent of the forested area of the park.

Empirically Exploring Higher Education Cultures of Assessment

ERIC Educational Resources Information Center

Fuller, Matthew B.; Skidmore, Susan T.; Bustamante, Rebecca M.; Holzweiss, Peggy C.

2016-01-01

Although touted as beneficial to student learning, cultures of assessment have not been examined adequately using validated instruments. Using data collected from a stratified, random sample (N = 370) of U.S. institutional research and assessment directors, the models tested in this study provide empirical support for the value of using the…

Drug and Alcohol Use by Canadian University Athletes: A National Survey.

ERIC Educational Resources Information Center

Spence, John C.; Gauvin, Lise

1996-01-01

Using a stratified random sampling procedure, 754 student athletes were surveyed regarding drug and alcohol use in eight different sports from eight universities across Canada. Provides statistics of substances athletes reported using, including pain medications, weight loss products, anabolic steroids, smokeless tobacco products, alcohol,…

Predictors of Eligibility for ESY. Final Report.

ERIC Educational Resources Information Center

Browder, Diane M.; And Others

Evaluation of eligibility for extended school year (ESY) services was made based on informaton contained in school files in a stratified sampling across Pennsylvania. Subjects had been classified as severely and profoundly mentally retarded and were divided into groups based on eligibility for programming in excess of 180 days or ineligibility for…

Causative factors and countermeasures for rural and suburban pedestrian accidents : accident data collection and analysis

DOT National Transportation Integrated Search

1977-03-01

The objectives of the study were to collect and analyze data on rural pedestrian accidents and to identify potential countermeasures. Data on a stratified random sample of over 1,500 rural and suburban accidents from six states was collected during i...

School Nurse Communication Effectiveness with Physicians and Satisfaction with School Health Services

ERIC Educational Resources Information Center

Volkman, Julie E.; Hillemeier, Marianne M.

2008-01-01

This study examined school nurses' communication with community physicians and its relationship to school nurse satisfaction with school health services. A stratified random sample of school nurses in Pennsylvania (N = 615) were surveyed about communication effectiveness with community physicians, satisfaction with school health services for…

Water-Oriented Recreational Demand and Projections: Calculations for Western Lake Superior.

DTIC Science & Technology

1978-06-15

Documented boats-every 36th registration. The stratified sample gives maximum descrimination to boats over 20 feet in length. These are the boats that are...large boats. Because documented boats, by their nature, are rarely trailered, it was believed that less descrimination was required. Therefore, a smaller

The Contours of Tracking in North Carolina

ERIC Educational Resources Information Center

Kelly, Sean

2007-01-01

In this analysis of North Carolina high schools the author examines school tracking policies using an amended version of Sorensen's (1970) conceptualization of the organizational dimensions of tracking. Data from curriculum guides in a stratified sample of 92 high schools reveal both consistency and variation in how tracking is implemented at the…

Training Neighborhood Residents to Conduct a Survey

ERIC Educational Resources Information Center

Back, Susan Malone; Tseng, Wan-Chun; Li, Jiaqi; Wang, Yuanhua; Phan, Van Thanh; Yeter, Ibrahim Halil

2015-01-01

As a requirement for a federal neighborhood revitalization grant, the authors trained resident interviewers and coordinated the conduct of more than 1000 door-to-door interviews of a stratified random sample. The targeted area was a multiethnic, lower income neighborhood that continues to experience the effects of past segregation. Monitoring and…

APPLICATION OF A MULTIPURPOSE UNEQUAL-PROBABILITY STREAM SURVEY IN THE MID-ATLANTIC COASTAL PLAIN

EPA Science Inventory

A stratified random sample with unequal-probability selection was used to design a multipurpose survey of headwater streams in the Mid-Atlantic Coastal Plain. Objectives for data from the survey include unbiased estimates of regional stream conditions, and adequate coverage of un...

Change in Sense of Community: An Empirical Finding

ERIC Educational Resources Information Center

Loomis, Colleen; Dockett, Kathleen H.; Brodsky, Anne E.

2004-01-01

This study investigated changes in students' psychological sense of community (SOC) under two conditions of external threat against their urban, historically Black, public nonresidential university in a U.S. mid-Atlantic city. Two independent stratified random samples (N = 801 and N = 241) consisting of undergraduate and graduate women (61%) and…

EXTENT, PROPERTIES, AND LANDSCAPE SETTING OF GEOGRAPHICALLY ISOLATED WETLANDS IN URBAN SOUTHERN NEW ENGLAND WATERSHEDS

EPA Science Inventory

We assessed the extent and characteristics of geographically isolated wetlands (i.e., wetlands completely surrounded by upland) in a series of drainage basins in the urban northeast U.S. We employed a random sampling design that stratifies study sites according to their degree o...

Psychological Security-Insecurity of Illinois Central College Students.

ERIC Educational Resources Information Center

Grout, David R.

This study attempted to discover the distribution of feelings of security and insecurity in the population of Illinois Central College (ICC) and whether significant differences exist among various subgroups. A 10 per cent stratified random sample of students were administered Maslow's Security-Insecurity Inventory. No significant difference was…

Homophobia in Registered Nurses: Impact on LGB Youth

ERIC Educational Resources Information Center

Blackwell, Christopher W.; Kiehl, Ermalynn M.

2008-01-01

This study examined registered nurses' overall attitudes and homophobia towards gays and lesbians in the workplace. Homophobia scores, represented by the Attitudes Toward Lesbians and Gay Men (ATLG) Scale, was the dependent variable. Overall homophobia scores were assessed among a randomized stratified sample of registered nurses licensed in the…

The Analysis of Iranian Students' Persistence in Online Education

ERIC Educational Resources Information Center

Mahmodi, Mahdi; Ebrahimzade, Issa

2015-01-01

In the following research, the relationship between instructional interaction and student persistence in e-learning has been analyzed. In order to conduct a descriptive-analytic survey, 744 undergraduate e-students were selected by stratified random sampling method to examine not only the frequency and the methods of establishing an instructional…

Causative factors and countermeasures for rural and suburban pedestrian accidents : accident data collection and analysis--appendices

DOT National Transportation Integrated Search

1977-06-01

The objectives of the study were to collect and analyze data on rural pedestrian accidents and to identify potential countermeasures. Data on a stratified random sample of over 1,500 rural and suburban accidents from six states was collected during i...

ENVIRONMENTALLY STRATIFIED SAMPLING DESIGN FOR THE DEVELOPMENT OF THE GREAT LAKES ENVIRONMENTAL INDICATORS

EPA Science Inventory

Ecological indicators must be shown to be responsive to stress. For large-scale observational studies the best way to demonstrate responsiveness is by evaluating indicators along a gradient of stress, but such gradients are often unknown for a population of sites prior to site se...

Do Social Workers Make Better Child Welfare Workers than Non-Social Workers?

ERIC Educational Resources Information Center

Perry, Robin E.

2006-01-01

Objective: To empirically examine whether the educational background of child welfare workers in Florida impacts on performance evaluations of their work. Method: A proportionate, stratified random sample of supervisor and peer evaluations of child protective investigators and child protective service workers is conducted. ANOVA procedures are…

Perceptions of Professionalism among Individuals in the Child Care Field

ERIC Educational Resources Information Center

Martin, Sue; Meyer, James; Jones, Robin Caudle; Nelson, Laverne; Ting, Ling

2010-01-01

Individuals working with young children, birth through age five, continue to strive for professional recognition. Factors that contribute to a person's feelings about being a child care professional were investigated. Stratified random sampling was used for data collection. Participants in the study responded to mailed questionnaires concerning a…

Factors Associated with the Fulfillment of Residential Preferences.

ERIC Educational Resources Information Center

Hwang, Sean-Shong; Albrecht, Don E.

A 1983 survey of Texas homebuyers reveals a high degree of mismatch between the preferred and actual residence of homebuyers. Such mismatch is examined using social/psychological, life-cycle, racial, socioeconomic, and occupational factors as possible explanations. Questionnaires mailed to a stratified random sample of 960 homebuyers across 12…

Interpersonal Features and Functions of Nonsuicidal Self-Injury

ERIC Educational Resources Information Center

Muehlenkamp, Jennifer; Brausch, Amy; Quigley, Katherine; Whitlock, Janis

2013-01-01

Etiological models of nonsuicidal self-injury (NSSI) suggest interpersonal features may be important to understand this behavior, but social functions and correlates have not been extensively studied. This study addresses existing limitations by examining interpersonal correlates and functions of NSSI within a stratified random sample of 1,243…

Lake Superior Phytoplankton Characterization from the 2006 Probability Based Survey

EPA Science Inventory

We conducted a late summer probability based survey of Lake Superior in 2006 which consisted of 52 sites stratified across 3 depth zones. As part of this effort, we collected composite phytoplankton samples from the epilimnion and the fluorescence maxima (Fmax) at 29 of the site...

Teachers' Characteristics: Understanding the Decision to Refer for Special Education Placement

ERIC Educational Resources Information Center

Hauck, Deborah Z.

2010-01-01

This mixed method study examined elementary teachers' characteristics (efficacy, tolerance, and demographics) and their influences on the decision to refer African American students to special education. A stratified purposeful sample of 115 elementary teachers for the quantitative segment and a subsample of 13 teachers for the qualitative portion…

Factors Associated with Successful Functioning in American Indian Youths

ERIC Educational Resources Information Center

Silmere, Hile; Stiffman, Arlene Rubin

2006-01-01

This study examines environmental and cultural factors related to successful functioning in a stratified random sample of 401 American Indian youths. The success index included seven indicators: good mental health, being alcohol and drug free, absence of serious misbehavior, clean police record, good grades, positive psychosocial functioning, and…

Positive Reading Attitudes of Low-Income Bilingual Latinos

ERIC Educational Resources Information Center

Bussert-webb, Kathy M.; Zhang, Zhidong

2018-01-01

Many assume low-income, emergent bilingual Latinos have poor reading attitudes. To investigate this issue, we surveyed 1,503 Texas public high school students through stratified cluster sampling to determine their reading attitudes. Most represented Latinos and mixed-race Latinos/Whites who heard Spanish at home and whose mother tongue was…

Job Insecurity and Employee Well-Being.

ERIC Educational Resources Information Center

Vance, Robert J.; Kuhnert, Karl W.

This study explored the consequences of perceived job security and insecurity on the psychological and physical health of employees. Data were gathered from employees of a large midwestern manufacturing organization that produced products for material removal applications. Surveys were sent through company mail to a stratified random sample of 442…

Comparative analysis of whole mount processing and systematic sampling of radical prostatectomy specimens: pathological outcomes and risk of biochemical recurrence.

PubMed

Salem, Shady; Chang, Sam S; Clark, Peter E; Davis, Rodney; Herrell, S Duke; Kordan, Yakup; Wills, Marcia L; Shappell, Scott B; Baumgartner, Roxelyn; Phillips, Sharon; Smith, Joseph A; Cookson, Michael S; Barocas, Daniel A

2010-10-01

Whole mount processing is more resource intensive than routine systematic sampling of radical retropubic prostatectomy specimens. We compared whole mount and systematic sampling for detecting pathological outcomes, and compared the prognostic value of pathological findings across pathological methods. We included men (608 whole mount and 525 systematic sampling samples) with no prior treatment who underwent radical retropubic prostatectomy at Vanderbilt University Medical Center between January 2000 and June 2008. We used univariate and multivariate analysis to compare the pathological outcome detection rate between pathological methods. Kaplan-Meier curves and the log rank test were used to compare the prognostic value of pathological findings across pathological methods. There were no significant differences between the whole mount and the systematic sampling groups in detecting extraprostatic extension (25% vs 30%), positive surgical margins (31% vs 31%), pathological Gleason score less than 7 (49% vs 43%), 7 (39% vs 43%) or greater than 7 (12% vs 13%), seminal vesicle invasion (8% vs 10%) or lymph node involvement (3% vs 5%). Tumor volume was higher in the systematic sampling group and whole mount detected more multiple surgical margins (each p <0.01). There were no significant differences in the likelihood of biochemical recurrence between the pathological methods when patients were stratified by pathological outcome. Except for estimated tumor volume and multiple margins whole mount and systematic sampling yield similar pathological information. Each method stratifies patients into comparable risk groups for biochemical recurrence. Thus, while whole mount is more resource intensive, it does not appear to result in improved detection of clinically important pathological outcomes or prognostication. Copyright © 2010 American Urological Association Education and Research, Inc. Published by Elsevier Inc. All rights reserved.

Accounting for Incomplete Species Detection in Fish Community Monitoring

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

McManamay, Ryan A; Orth, Dr. Donald J; Jager, Yetta

2013-01-01

Riverine fish assemblages are heterogeneous and very difficult to characterize with a one-size-fits-all approach to sampling. Furthermore, detecting changes in fish assemblages over time requires accounting for variation in sampling designs. We present a modeling approach that permits heterogeneous sampling by accounting for site and sampling covariates (including method) in a model-based framework for estimation (versus a sampling-based framework). We snorkeled during three surveys and electrofished during a single survey in suite of delineated habitats stratified by reach types. We developed single-species occupancy models to determine covariates influencing patch occupancy and species detection probabilities whereas community occupancy models estimated speciesmore » richness in light of incomplete detections. For most species, information-theoretic criteria showed higher support for models that included patch size and reach as covariates of occupancy. In addition, models including patch size and sampling method as covariates of detection probabilities also had higher support. Detection probability estimates for snorkeling surveys were higher for larger non-benthic species whereas electrofishing was more effective at detecting smaller benthic species. The number of sites and sampling occasions required to accurately estimate occupancy varied among fish species. For rare benthic species, our results suggested that higher number of occasions, and especially the addition of electrofishing, may be required to improve detection probabilities and obtain accurate occupancy estimates. Community models suggested that richness was 41% higher than the number of species actually observed and the addition of an electrofishing survey increased estimated richness by 13%. These results can be useful to future fish assemblage monitoring efforts by informing sampling designs, such as site selection (e.g. stratifying based on patch size) and determining effort required (e.g. number of sites versus occasions).« less

Low Altitude AVIRIS Data for Mapping Landform Types on West Ship Island, Mississippi

NASA Technical Reports Server (NTRS)

Spruce, Joseph; Otvos, Ervin; Giardino, Marco

2002-01-01

A chain of barrier islands provides protection against hurricanes and severe storms along the south and southeastern shores of the United States. Barrier island landform types can be spectrally similar and as small as a few meters across, making highly detailed maps difficult to produce. To determine whether high-resolution airborne hyperspectral imagery could provide detailed maps of barrier island landform types, we used low-altitude hyperspectral and multispectral imagery to map surface environments of West Ship Island, Mississippi. We employed 3.4-meter AVIRIS hyperspectral imagery acquired in July 1999 and 0.5-meter ADAR multispectral data acquired in November 1997. The data were co-registered to digital ortho aerial imagery, and the AVIRIS data was scaled to ground reflectance using ATREM software. Unsupervised classification of AVIRIS and ADAR data proceeded using ISODATA clustering techniques. The resulting landform maps were field-checked and compared to aerial photography and digital elevation maps. Preliminary analyses indicated that the AVIRIS classification mapped more landform types, while the ADAR-based map enabled smaller patches to be identified. Used together, these maps provided a means to assess landform distributions of West Ship Island before and after Hurricane Gorges. Classification accuracy is being addressed through photo-interpretation and field surveys of sample areas selected with stratified random sampling.

Low Altitude AVIRIS Data for Mapping Landform Types on West Ship Island, Mississippi

NASA Technical Reports Server (NTRS)

Spruce, Joseph; Otvos, Ervin; Giardino, Marco

2003-01-01

A chain of barrier islands provides protection against hurricanes and severe storms along the southern and southeastern shores of the Unites States. Barrier island landform types can be spectrally similar and as small as a few meters across, making highly detailed maps difficult to produce. To determine whether high-resolution airborne hyperspectral imagery could provide detailed maps of barrier island landform types, we used low-altitude hyperspectral and multispectral imagery to map surface environments of West Ship Island, Mississippi. We employed 3.4 meter AVIRIS hyperspectral imagery acquired in July 1999 and 0.5 meter ADAR multispectral data acquired in November 1997. The data were co-registered to digital ortho aerial imagery, and the AVIRIS data was scaled to ground reflectance using ATREM software. Unsupervised classification of AVIRIS and ADAR data proceeded using ISODATA clustering techniques. The resulting landform maps were field-checked and compared to aerial photography and digital elevation maps. Preliminary analyses indicated that the AVIRIS classification mapped more landform types, while the ADAR-based map enabled smaller patches to be identified. Used together, these maps provided a means to assess landform distributions of West Ship Island before and after Hurricane Georges. Classification accuracy is being assessed through photo-interpretation and field surveys of sample areas selected with stratified random sampling.

Realistic Matematic Approach through Numbered Head Together Learning Model

NASA Astrophysics Data System (ADS)

Sugihatno, A. C. M. S.; Budiyono; Slamet, I.

2017-09-01

Recently, the teaching process which is conducted based on teacher center affect the students interaction in the class. It causes students become less interest to participate. That is why teachers should be more creative in designing learning using other types of cooperative learning model. Therefore, this research is aimed to implement NHT with RMA in the teaching process. We utilize NHT since it is a variant of group discussion whose aim is giving a chance to the students to share their ideas related to the teacher’s question. By using NHT in the class, a teacher can give a better understanding about the material which is given with the help of Realistic Mathematics Approach (RMA) which known for its real problem contex. Meanwhile, the researcher assumes instead of selecting teaching model, Adversity Quotient (AQ) of student also influences students’ achievement. This research used the quasi experimental research. The samples is 60 students in junior high school, it was taken by using the stratified cluster random sampling technique. The results show NHT-RMA gives a better learning achievement of mathematics than direct teaching model and NHT-RMA teaching model with categorized as high AQ show different learning achievement from the students with categorized as moderate and low AQ.

Bacterial contamination of re-usable laryngoscope blades during the course of daily anaesthetic practice.

PubMed

Lowman, Warren; Venter, Laurissa; Scribante, Juan

2013-02-19

Hospital-acquired infections (HAIs) are largely preventable through risk analysis and modification of practice. Anaesthetic practice plays a limited role in the prevention of HAIs, although laryngoscope use and decontamination is an area of concern. We aimed to assess the level of microbial contamination of re-usable laryngoscope blades at a public hospital in South Africa. The theatre complex of a secondary-level public hospital in Johannesburg. Blades from two different theatres were sampled twice daily, using a standardised technique, over a 2-week period. Samples were quantitatively assessed for microbial contamination, and stratified by area on blade, theatre and time using Fisher's exact test. A contamination rate of 57.3% (63/110) was found, with high-level contamination accounting for 22.2% of these. Common commensals were the most frequently isolated micro-organisms (79.1%), but important hospital pathogens such as Enterobacter species and Acinetobacter baumannii were isolated from blades with high-level contamination. No significant difference in the level of microbial contamination by area on blade, theatre or time was found (p<0.05). A combination of sub-optimal decontamination and improper handling of laryngoscopes after decontamination results in significant microbial contamination of re-usable laryngoscope blades. There is an urgent need to review protocols and policies surrounding the use of these blades.

Concentrations of polycyclic aromatic hydrocarbons and inorganic constituents in ambient surface soils, Chicago, Illinois: 2001-2002

USGS Publications Warehouse

Kay, R.T.; Arnold, T.L.; Cannon, W.F.; Graham, D.

2008-01-01

Samples of ambient surface soils were collected from 56 locations in Chicago, Illinois, using stratified random sampling techniques and analyzed for polycyclic aromatic hydrocarbon (PAH) compounds and inorganic constituents. PAHs appear to be derived primarily from combustion of fossil fuels and may be affected by proximity to industrial operations, but do not appear to be substantially affected by the organic carbon content of the soil, proximity to nonindustrial land uses, or proximity to a roadway. Atmospheric settling of particulate matter appears to be an important mechanism for the placement of PAH compounds into soils. Concentrations of most inorganic constituents are affected primarily by soil-forming processes. Concentrations of lead, arsenic, mercury, calcium, magnesium, phosphorus, copper, molybdenum, zinc, and selenium are elevated in ambient surface soils in Chicago in comparison to the surrounding area, indicating anthropogenic sources for these elements in Chicago soils. Concentrations of calcium and magnesium in Chicago soils appear to reflect the influence of the carbonate bedrock parent material on the chemical composition of the soil, although the effects of concrete and road fill cannot be discounted. Concentrations of inorganic constituents appear to be largely unaffected by the type of nearby land use. Copyright ?? Taylor & Francis Group, LLC.

Outcomes of parental use of psychological aggression on children: a structural model from Sri Lanka.

PubMed

de Zoysa, Piyanjali; Newcombe, Peter A; Rajapakse, Lalini

2010-08-01

The objective of this study was to explore the existence and, if so, the nature of the association between parental use of psychological aggression and psychological maladjustment in a 12-year-old Sri Lankan school population. A stratified random sampling technique was used to select 1,226 children from Colombo district schools. Three instruments, validated in the Sri Lankan context, were used to collect data on children's experience of psychological aggression, its psychological outcomes, and psychosocial correlates. The annual prevalence of psychological aggression reported by the study sample was 75%. A predictive model for psychological outcomes was examined. The experience of psychological aggression was shown to be moderately, but directly and significantly, associated with psychological maladjustment in children. This association was mediated by non-parentto-child violence-the child's knowledge of violence between the parents, experience of teacher violence, exposure to peer violence, and violence in the child's community. However, the child's report of a nurturant parent-child relationship did not impact on the association between psychological aggression and psychological maladjustment. The study also indicated that greater the child's experience of non-parent-to-child violence, the greater is his/her own level of hostility and aggression. These findings show that although many Sri Lankan parents use psychological aggression it has negative consequences for their children.

Sickness absenteeism and associated factors among horticulture employees in lume district, southeast Ethiopia.

PubMed

Tadesse, Sebsibe; Ebrahim, Kamil; Gizaw, Zemichael

2015-01-01

Sickness absenteeism is the major occupational health problem in developing countries where the majority of working population are engaged in hazardous sectors, such as agriculture. However, there is a dearth of studies clarifying the situation in most of Subsaharan African countries, like Ethiopia. The present study determined the magnitude of sickness absenteeism and associated factors among horticulture employees in Lume District, southeast Ethiopia. An institutional-based cross-sectional study was conducted among horticulture employees in Lume District, southeast Ethiopia from March to May 2014. Stratified sampling followed by simple random sampling techniques was used to select the study participants. A pre-tested and structured questionnaire was used to collect data. Multivariable analyses were employed to see the effect of explanatory variables on dependent variable. The magnitude of sickness absenteeism was 58.8 % [95 % CI: (54.9, 62.5)] in the past three months. Absence of periodic medical checkup, working for more than 48 h per week, working overtime, job dissatisfaction, and job stress were factors significantly associated with sickness absenteeism. In this study a relatively higher rate of sickness absenteeism was reported compared to other studies. Interventions to reduce sickness absenteeism should focus on areas, such as periodic medical checkup, monitoring work schedules, improving employees' job satisfaction, and managing job stress.

Gender differences in leisure-time versus non-leisure-time physical activity among Saudi adolescents.

PubMed

Al-Sobayel, Hana; Al-Hazzaa, Hazzaa M; Abahussain, Nanda A; Qahwaji, Dina M; Musaiger, Abdulrahman O

2015-01-01

The aim of the study was to examine the gender differences and predictors of leisure versus non-leisure time physical activities among Saudi adolescents aged 14-19 years. The multistage stratified cluster random sampling technique was used. A sample of 1,388 males and 1,500 females enrolled in secondary schools in three major cities in Saudi Arabia was included. Anthropometric measurements were performed and Body Mass Index was calculated. Physical activity, sedentary behaviours and dietary habits were measured using a self-reported validated questionnaire. The total time spent in leisure and non-leisure physical activity per week was 90 and 77 minutes, respectively. The males spent more time per week in leisure-time physical activities than females. Females in private schools spent more time during the week in leisure-time physical activities, compared to females in Stateschools. There was a significant difference between genders by obesity status interaction in leisure-time physical activity. Gender, and other factors, predicted total duration spent in leisure-time and non-leisure-time physical activity. The study showed that female adolescents are much less active than males, especially in leisure-time physical activities. Programmes to promote physical activity among adolescents are urgently needed, with consideration of gender differences.

Knowledge of the Nigerian Code of Health Research Ethics Among Biomedical Researchers in Southern Nigeria.

PubMed

Ogunrin, Olubunmi A; Daniel, Folasade; Ansa, Victor

2016-12-01

Responsibility for protection of research participants from harm and exploitation rests on Research Ethics Committees and principal investigators. The Nigerian National Code of Health Research Ethics defines responsibilities of stakeholders in research so its knowledge among researchers will likely aid ethical conduct of research. The levels of awareness and knowledge of the Code among biomedical researchers in southern Nigerian research institutions was assessed. Four institutions were selected using a stratified random sampling technique. Research participants were selected by purposive sampling and completed a pre-tested structured questionnaire. A total of 102 biomedical researchers completed the questionnaires. Thirty percent of the participants were aware of the National Code though 64% had attended at least one training seminar in research ethics. Twenty-five percent had a fairly acceptable knowledge (scores 50%-74%) and 10% had excellent knowledge of the code (score ≥75%). Ninety-five percent expressed intentions to learn more about the National Code and agreed that it is highly relevant to the ethical conduct of research. Awareness and knowledge of the Code were found to be very limited among biomedical researchers in southern Nigeria. There is need to improve awareness and knowledge through ethics seminars and training. Use of existing Nigeria-specific online training resources is also encouraged.

Relationship of saving habit determinants among undergraduate students: A case study of UiTM Negeri Sembilan, Kampus Seremban

NASA Astrophysics Data System (ADS)

Syahrom, N. S.; Nasrudin, N. S.; Mohamad Yasin, N.; Azlan, N.; Manap, N.

2017-08-01

It has been reported that students are already accumulating substantial debt from higher education fees and their spending habit are at a critical stage. These situations cause the youngsters facing bankruptcy if they cannot improve their saving habit. Many researches have acknowledged that the determinants of saving habit include financial management, parental socialization, peer influence, and self-control. However, there remains a need for investigating the relationship between these determinants in order to avoid bankruptcy among youngsters. The objectives of this study are to investigate the relationship between saving habit determinants and to generate a statistical model based on the determinants of saving habit. Data collection method used is questionnaire and its scope is undergraduate students of UiTM Negeri Sembilan, Kampus Seremban. Samples are chosen by using stratified probability sampling technique and cross-sectional method is used as the research design. The results are then analysed by using descriptive analysis, reliability test, Pearson Correlation, and Multiple Linear Regression analysis. It shows that saving habit and self-control has no relationship. It means that students with less self-control tend to save less. A statistical model has been generated that incorporated this relationship. This study is significant to help the students save more by having high self-control.

Mapping aboveground woody biomass using forest inventory, remote sensing and geostatistical techniques.

PubMed

Yadav, Bechu K V; Nandy, S

2015-05-01

Mapping forest biomass is fundamental for estimating CO₂ emissions, and planning and monitoring of forests and ecosystem productivity. The present study attempted to map aboveground woody biomass (AGWB) integrating forest inventory, remote sensing and geostatistical techniques, viz., direct radiometric relationships (DRR), k-nearest neighbours (k-NN) and cokriging (CoK) and to evaluate their accuracy. A part of the Timli Forest Range of Kalsi Soil and Water Conservation Division, Uttarakhand, India was selected for the present study. Stratified random sampling was used to collect biophysical data from 36 sample plots of 0.1 ha (31.62 m × 31.62 m) size. Species-specific volumetric equations were used for calculating volume and multiplied by specific gravity to get biomass. Three forest-type density classes, viz. 10-40, 40-70 and >70% of Shorea robusta forest and four non-forest classes were delineated using on-screen visual interpretation of IRS P6 LISS-III data of December 2012. The volume in different strata of forest-type density ranged from 189.84 to 484.36 m(3) ha(-1). The total growing stock of the forest was found to be 2,024,652.88 m(3). The AGWB ranged from 143 to 421 Mgha(-1). Spectral bands and vegetation indices were used as independent variables and biomass as dependent variable for DRR, k-NN and CoK. After validation and comparison, k-NN method of Mahalanobis distance (root mean square error (RMSE) = 42.25 Mgha(-1)) was found to be the best method followed by fuzzy distance and Euclidean distance with RMSE of 44.23 and 45.13 Mgha(-1) respectively. DRR was found to be the least accurate method with RMSE of 67.17 Mgha(-1). The study highlighted the potential of integrating of forest inventory, remote sensing and geostatistical techniques for forest biomass mapping.

Mapping and predicting mortality from systemic sclerosis.

PubMed

Elhai, Muriel; Meune, Christophe; Boubaya, Marouane; Avouac, Jérôme; Hachulla, Eric; Balbir-Gurman, Alexandra; Riemekasten, Gabriela; Airò, Paolo; Joven, Beatriz; Vettori, Serena; Cozzi, Franco; Ullman, Susanne; Czirják, László; Tikly, Mohammed; Müller-Ladner, Ulf; Caramaschi, Paola; Distler, Oliver; Iannone, Florenzo; Ananieva, Lidia P; Hesselstrand, Roger; Becvar, Radim; Gabrielli, Armando; Damjanov, Nemanja; Salvador, Maria J; Riccieri, Valeria; Mihai, Carina; Szücs, Gabriella; Walker, Ulrich A; Hunzelmann, Nicolas; Martinovic, Duska; Smith, Vanessa; Müller, Carolina de Souza; Montecucco, Carlo Maurizio; Opris, Daniela; Ingegnoli, Francesca; Vlachoyiannopoulos, Panayiotis G; Stamenkovic, Bojana; Rosato, Edoardo; Heitmann, Stefan; Distler, Jörg H W; Zenone, Thierry; Seidel, Matthias; Vacca, Alessandra; Langhe, Ellen De; Novak, Srdan; Cutolo, Maurizio; Mouthon, Luc; Henes, Jörg; Chizzolini, Carlo; Mühlen, Carlos Alberto von; Solanki, Kamal; Rednic, Simona; Stamp, Lisa; Anic, Branimir; Santamaria, Vera Ortiz; De Santis, Maria; Yavuz, Sule; Sifuentes-Giraldo, Walter Alberto; Chatelus, Emmanuel; Stork, Jiri; Laar, Jacob van; Loyo, Esthela; García de la Peña Lefebvre, Paloma; Eyerich, Kilian; Cosentino, Vanesa; Alegre-Sancho, Juan Jose; Kowal-Bielecka, Otylia; Rey, Grégoire; Matucci-Cerinic, Marco; Allanore, Yannick

2017-11-01

To determine the causes of death and risk factors in systemic sclerosis (SSc). Between 2000 and 2011, we examined the death certificates of all French patients with SSc to determine causes of death. Then we examined causes of death and developed a score associated with all-cause mortality from the international European Scleroderma Trials and Research (EUSTAR) database. Candidate prognostic factors were tested by Cox proportional hazards regression model by single variable analysis, followed by a multiple variable model stratified by centres. The bootstrapping technique was used for internal validation. We identified 2719 French certificates of deaths related to SSc, mainly from cardiac (31%) and respiratory (18%) causes, and an increase in SSc-specific mortality over time. Over a median follow-up of 2.3 years, 1072 (9.6%) of 11 193 patients from the EUSTAR sample died, from cardiac disease in 27% and respiratory causes in 17%. By multiple variable analysis, a risk score was developed, which accurately predicted the 3-year mortality, with an area under the curve of 0.82. The 3-year survival of patients in the upper quartile was 53%, in contrast with 98% in the first quartile. Combining two complementary and detailed databases enabled the collection of an unprecedented 3700 deaths, revealing the major contribution of the cardiopulmonary system to SSc mortality. We also developed a robust score to risk-stratify these patients and estimate their 3-year survival. With the emergence of new therapies, these important observations should help caregivers plan and refine the monitoring and management to prolong these patients' survival. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

Comparative evidence of the consumption from fast-food restaurants between normal-weight and obese Saudi schoolchildren.

PubMed

Alturki, Hmidan A; Brookes, Denise Sk; Davies, Peter Sw

2018-04-06

To provide an in-depth analysis of the relationship between obesity and fast-food consumption by comparing urban obese and normal-weight Saudi Arabian children. A multicentre cross-sectional study was conducted from December 2015 to March 2016. Participants were divided into two groups (normal weight and obese) and further stratified by sex. Groups were randomly selected using a multistage stratified cluster-sampling technique. A self-paced questionnaire was used to collect data relating to food consumption. Weight height and waist circumference were measured and bioelectrical impedance analysis was performed in all children. Capital of Saudi Arabia, Riyadh. Children aged 9·00-11·99 years (n 1023). Compared with normal-weight groups, intake frequency of fast food/week was higher among the obese groups (P<0·001), irrespective of fast-food consumption outside (P<0·001) or inside (P<0·001) the home; and larger portion sizes were preferred in obese groups (P<0·001). Families eating fast-food meals together was a protective factor against obesity (OR; 95 % CI: 2·67; 1·44, 4·96, P<0·001), with similar results for families ordering from a 'healthy meals menu' for their children (1·90; 1·24, 2·90, P=0·002). Taste of fast foods (P=0·021), child-friendly menu (P=0·020) and meal cost (P<0·001) were identified as main reasons why parents took their children to fast-food restaurants; these data were replicated for parents with obese boys, but not girls. Development of effective interventions to reduce fast-food consumption in Saudi Arabian schoolchildren requires greater research-based evidence of fast-food consumption habits and practices associated with increased childhood obesity.

Active animal health surveillance in European Union Member States: gaps and opportunities.

PubMed

Bisdorff, B; Schauer, B; Taylor, N; Rodríguez-Prieto, V; Comin, A; Brouwer, A; Dórea, F; Drewe, J; Hoinville, L; Lindberg, A; Martinez Avilés, M; Martínez-López, B; Peyre, M; Pinto Ferreira, J; Rushton, J; VAN Schaik, G; Stärk, K D C; Staubach, C; Vicente-Rubiano, M; Witteveen, G; Pfeiffer, D; Häsler, B

2017-03-01

Animal health surveillance enables the detection and control of animal diseases including zoonoses. Under the EU-FP7 project RISKSUR, a survey was conducted in 11 EU Member States and Switzerland to describe active surveillance components in 2011 managed by the public or private sector and identify gaps and opportunities. Information was collected about hazard, target population, geographical focus, legal obligation, management, surveillance design, risk-based sampling, and multi-hazard surveillance. Two countries were excluded due to incompleteness of data. Most of the 664 components targeted cattle (26·7%), pigs (17·5%) or poultry (16·0%). The most common surveillance objectives were demonstrating freedom from disease (43·8%) and case detection (26·8%). Over half of components applied risk-based sampling (57·1%), but mainly focused on a single population stratum (targeted risk-based) rather than differentiating between risk levels of different strata (stratified risk-based). About a third of components were multi-hazard (37·3%). Both risk-based sampling and multi-hazard surveillance were used more frequently in privately funded components. The study identified several gaps (e.g. lack of systematic documentation, inconsistent application of terminology) and opportunities (e.g. stratified risk-based sampling). The greater flexibility provided by the new EU Animal Health Law means that systematic evaluation of surveillance alternatives will be required to optimize cost-effectiveness.

A technique for measuring vertically and horizontally polarized microwave brightness temperatures using electronic polarization-basis rotation

NASA Technical Reports Server (NTRS)

Gasiewski, Albin J.

1992-01-01

This technique for electronically rotating the polarization basis of an orthogonal-linear polarization radiometer is based on the measurement of the first three feedhorn Stokes parameters, along with the subsequent transformation of this measured Stokes vector into a rotated coordinate frame. The technique requires an accurate measurement of the cross-correlation between the two orthogonal feedhorn modes, for which an innovative polarized calibration load was developed. The experimental portion of this investigation consisted of a proof of concept demonstration of the technique of electronic polarization basis rotation (EPBR) using a ground based 90-GHz dual orthogonal-linear polarization radiometer. Practical calibration algorithms for ground-, aircraft-, and space-based instruments were identified and tested. The theoretical effort consisted of radiative transfer modeling using the planar-stratified numerical model described in Gasiewski and Staelin (1990).

Estimating juvenile Chinook salmon (Oncorhynchus tshawytscha) abundance from beach seine data collected in the Sacramento–San Joaquin Delta and San Francisco Bay, California

USGS Publications Warehouse

Perry, Russell W.; Kirsch, Joseph E.; Hendrix, A. Noble

2016-06-17

Resource managers rely on abundance or density metrics derived from beach seine surveys to make vital decisions that affect fish population dynamics and assemblage structure. However, abundance and density metrics may be biased by imperfect capture and lack of geographic closure during sampling. Currently, there is considerable uncertainty about the capture efficiency of juvenile Chinook salmon (Oncorhynchus tshawytscha) by beach seines. Heterogeneity in capture can occur through unrealistic assumptions of closure and from variation in the probability of capture caused by environmental conditions. We evaluated the assumptions of closure and the influence of environmental conditions on capture efficiency and abundance estimates of Chinook salmon from beach seining within the Sacramento–San Joaquin Delta and the San Francisco Bay. Beach seine capture efficiency was measured using a stratified random sampling design combined with open and closed replicate depletion sampling. A total of 56 samples were collected during the spring of 2014. To assess variability in capture probability and the absolute abundance of juvenile Chinook salmon, beach seine capture efficiency data were fitted to the paired depletion design using modified N-mixture models. These models allowed us to explicitly test the closure assumption and estimate environmental effects on the probability of capture. We determined that our updated method allowing for lack of closure between depletion samples drastically outperformed traditional data analysis that assumes closure among replicate samples. The best-fit model (lowest-valued Akaike Information Criterion model) included the probability of fish being available for capture (relaxed closure assumption), capture probability modeled as a function of water velocity and percent coverage of fine sediment, and abundance modeled as a function of sample area, temperature, and water velocity. Given that beach seining is a ubiquitous sampling technique for many species, our improved sampling design and analysis could provide significant improvements in density and abundance estimation.

An approach to checking case-crossover analyses based on equivalence with time-series methods.

PubMed

Lu, Yun; Symons, James Morel; Geyh, Alison S; Zeger, Scott L

2008-03-01

The case-crossover design has been increasingly applied to epidemiologic investigations of acute adverse health effects associated with ambient air pollution. The correspondence of the design to that of matched case-control studies makes it inferentially appealing for epidemiologic studies. Case-crossover analyses generally use conditional logistic regression modeling. This technique is equivalent to time-series log-linear regression models when there is a common exposure across individuals, as in air pollution studies. Previous methods for obtaining unbiased estimates for case-crossover analyses have assumed that time-varying risk factors are constant within reference windows. In this paper, we rely on the connection between case-crossover and time-series methods to illustrate model-checking procedures from log-linear model diagnostics for time-stratified case-crossover analyses. Additionally, we compare the relative performance of the time-stratified case-crossover approach to time-series methods under 3 simulated scenarios representing different temporal patterns of daily mortality associated with air pollution in Chicago, Illinois, during 1995 and 1996. Whenever a model-be it time-series or case-crossover-fails to account appropriately for fluctuations in time that confound the exposure, the effect estimate will be biased. It is therefore important to perform model-checking in time-stratified case-crossover analyses rather than assume the estimator is unbiased.

Does History Repeat Itself? Wavelets and the Phylodynamics of Influenza A

PubMed Central

Tom, Jennifer A.; Sinsheimer, Janet S.; Suchard, Marc A.

2012-01-01

Unprecedented global surveillance of viruses will result in massive sequence data sets that require new statistical methods. These data sets press the limits of Bayesian phylogenetics as the high-dimensional parameters that comprise a phylogenetic tree increase the already sizable computational burden of these techniques. This burden often results in partitioning the data set, for example, by gene, and inferring the evolutionary dynamics of each partition independently, a compromise that results in stratified analyses that depend only on data within a given partition. However, parameter estimates inferred from these stratified models are likely strongly correlated, considering they rely on data from a single data set. To overcome this shortfall, we exploit the existing Monte Carlo realizations from stratified Bayesian analyses to efficiently estimate a nonparametric hierarchical wavelet-based model and learn about the time-varying parameters of effective population size that reflect levels of genetic diversity across all partitions simultaneously. Our methods are applied to complete genome influenza A sequences that span 13 years. We find that broad peaks and trends, as opposed to seasonal spikes, in the effective population size history distinguish individual segments from the complete genome. We also address hypotheses regarding intersegment dynamics within a formal statistical framework that accounts for correlation between segment-specific parameters. PMID:22160768

Integrating remote sensing and terrain data in forest fire modeling

NASA Astrophysics Data System (ADS)

Medler, Michael Johns

Forest fire policies are changing. Managers now face conflicting imperatives to re-establish pre-suppression fire regimes, while simultaneously preventing resource destruction. They must, therefore, understand the spatial patterns of fires. Geographers can facilitate this understanding by developing new techniques for mapping fire behavior. This dissertation develops such techniques for mapping recent fires and using these maps to calibrate models of potential fire hazards. In so doing, it features techniques that strive to address the inherent complexity of modeling the combinations of variables found in most ecological systems. Image processing techniques were used to stratify the elements of terrain, slope, elevation, and aspect. These stratification images were used to assure sample placement considered the role of terrain in fire behavior. Examination of multiple stratification images indicated samples were placed representatively across a controlled range of scales. The incorporation of terrain data also improved preliminary fire hazard classification accuracy by 40%, compared with remotely sensed data alone. A Kauth-Thomas transformation (KT) of pre-fire and post-fire Thematic Mapper (TM) remotely sensed data produced brightness, greenness, and wetness images. Image subtraction indicated fire induced change in brightness, greenness, and wetness. Field data guided a fuzzy classification of these change images. Because fuzzy classification can characterize a continuum of a phenomena where discrete classification may produce artificial borders, fuzzy classification was found to offer a range of fire severity information unavailable with discrete classification. These mapped fire patterns were used to calibrate a model of fire hazards for the entire mountain range. Pre-fire TM, and a digital elevation model produced a set of co-registered images. Training statistics were developed from 30 polygons associated with the previously mapped fire severity. Fuzzy classifications of potential burn patterns were produced from these images. Observed field data values were displayed over the hazard imagery to indicate the effectiveness of the model. Areas that burned without suppression during maximum fire severity are predicted best. Areas with widely spaced trees and grassy understory appear to be misrepresented, perhaps as a consequence of inaccuracies in the initial fire mapping.

Estimating leaf functional traits by inversion of PROSPECT: Assessing leaf dry matter content and specific leaf area in mixed mountainous forest

NASA Astrophysics Data System (ADS)

Ali, Abebe Mohammed; Darvishzadeh, Roshanak; Skidmore, Andrew K.; Duren, Iris van; Heiden, Uta; Heurich, Marco

2016-03-01

Assessments of ecosystem functioning rely heavily on quantification of vegetation properties. The search is on for methods that produce reliable and accurate baseline information on plant functional traits. In this study, the inversion of the PROSPECT radiative transfer model was used to estimate two functional leaf traits: leaf dry matter content (LDMC) and specific leaf area (SLA). Inversion of PROSPECT usually aims at quantifying its direct input parameters. This is the first time the technique has been used to indirectly model LDMC and SLA. Biophysical parameters of 137 leaf samples were measured in July 2013 in the Bavarian Forest National Park, Germany. Spectra of the leaf samples were measured using an ASD FieldSpec3 equipped with an integrating sphere. PROSPECT was inverted using a look-up table (LUT) approach. The LUTs were generated with and without using prior information. The effect of incorporating prior information on the retrieval accuracy was studied before and after stratifying the samples into broadleaf and conifer categories. The estimated values were evaluated using R2 and normalized root mean square error (nRMSE). Among the retrieved variables the lowest nRMSE (0.0899) was observed for LDMC. For both traits higher R2 values (0.83 for LDMC and 0.89 for SLA) were discovered in the pooled samples. The use of prior information improved accuracy of the retrieved traits. The strong correlation between the estimated traits and the NIR/SWIR region of the electromagnetic spectrum suggests that these leaf traits could be assessed at canopy level by using remotely sensed data.

Community-level influences on women's experience of intimate partner violence and terminated pregnancy in Nigeria: a multilevel analysis

PubMed Central

2012-01-01

Background Intimate partner violence (IPV) is a major public health problem with serious consequences for women’s physical, mental, sexual and reproductive health. Reproductive health outcomes such as unwanted and terminated pregnancies, fetal loss or child loss during infancy, non-use of family planning methods, and high fertility are increasingly recognized. However, little is known about the role of community influences on women's experience of IPV and its effect on terminated pregnancy, given the increased awareness of IPV being a product of social context. This study sought to examine the role of community-level norms and characteristics in the association between IPV and terminated pregnancy in Nigeria. Methods Multilevel logistic regression analyses were performed on nationally-representative cross-sectional data including 19,226 women aged 15–49 years in Nigeria. Data were collected by a stratified two-stage sampling technique, with 888 primary sampling units (PSUs) selected in the first sampling stage, and 7,864 households selected through probability sampling in the second sampling stage. Results Women who had experienced physical IPV, sexual IPV, and any IPV were more likely to have terminated a pregnancy compared to women who had not experienced these IPV types. IPV types were significantly associated with factors reflecting relationship control, relationship inequalities, and socio-demographic characteristics. Characteristics of the women aggregated at the community level (mean education, justifying wife beating, mean age at first marriage, and contraceptive use) were significantly associated with IPV types and terminated pregnancy. Conclusion Findings indicate the role of community influence in the association between IPV-exposure and terminated pregnancy, and stress the need for screening women seeking abortions for a history of abuse. PMID:23150987

Differential color space analysis for investigating nutrient content in a puréed food dilution-flavor matrix: a step toward objective malnutrition risk assessment

NASA Astrophysics Data System (ADS)

Pfisterer, Kaylen J.; Amelard, Robert; Wong, Alexander

2018-02-01

Dysphagia (swallowing difficulty) increases risk for malnutrition and affects at least 15% of American older adults, and 590 million people worldwide. Malnutrition is associated with increased mortality, increased morbidity, decreased quality of life, and accounts for over $15 billion (USD) health-care related costs each year. While modified texture diets (e.g., puréed food) reduce the risk of choking, quality assurance is necessary for monitoring nutrient density to ensure food meets nutritional requirements. However, current methods are subjective and time consuming. The purpose of this study was to investigate the feasibility of optical techniques for an objective assessment of food nutrient density in puréed samples. Motivated by a theoretical optical dilution model, broadband spectral images of commercially prepared purée samples were acquired. Specifically, 13 flavors at five dilutions relative to initial concentration, each with six replicates, were acquired for a total of 390 samples. Purée samples were prepared and loaded onto a white reflectance back plane to maximize photon traversal path length through the purée. The sample was illuminated with a tungsten-halogen illumination source fitted with a front glass fabric diffuser for spatially homogeneous illumination. This broadband illuminant was chosen to observe as many food-light spectral absorbance interactions as possible. Flavor-stratified correlation analysis was performed on this food image dataset to investigate the relationship between nutritional information and color space transformations. A special case of blueberry is presented as the effect of anthocyanins was quantitatively observed through normalized spectral trends in response to pH perturbations across dilutions.

Community-level influences on women's experience of intimate partner violence and terminated pregnancy in Nigeria: a multilevel analysis.

PubMed

Antai, Diddy; Adaji, Sunday

2012-11-14

Intimate partner violence (IPV) is a major public health problem with serious consequences for women's physical, mental, sexual and reproductive health. Reproductive health outcomes such as unwanted and terminated pregnancies, fetal loss or child loss during infancy, non-use of family planning methods, and high fertility are increasingly recognized. However, little is known about the role of community influences on women's experience of IPV and its effect on terminated pregnancy, given the increased awareness of IPV being a product of social context. This study sought to examine the role of community-level norms and characteristics in the association between IPV and terminated pregnancy in Nigeria. Multilevel logistic regression analyses were performed on nationally-representative cross-sectional data including 19,226 women aged 15-49 years in Nigeria. Data were collected by a stratified two-stage sampling technique, with 888 primary sampling units (PSUs) selected in the first sampling stage, and 7,864 households selected through probability sampling in the second sampling stage. Women who had experienced physical IPV, sexual IPV, and any IPV were more likely to have terminated a pregnancy compared to women who had not experienced these IPV types.IPV types were significantly associated with factors reflecting relationship control, relationship inequalities, and socio-demographic characteristics. Characteristics of the women aggregated at the community level (mean education, justifying wife beating, mean age at first marriage, and contraceptive use) were significantly associated with IPV types and terminated pregnancy. Findings indicate the role of community influence in the association between IPV-exposure and terminated pregnancy, and stress the need for screening women seeking abortions for a history of abuse.

Awareness of Dental Trauma Management among School Teachers of Kannur, Kerala, India

PubMed Central

Peedikayil, Faizal C; Premkumar, Chandru T; Narasimhan, Dhanesh; Jose, Deepak

2017-01-01

Introduction Dental trauma can overtake dental caries and periodontal disease as the most significant threat to dental health among young people. The prognosis of traumatized teeth depends on prompt and appropriate treatment. The role of school teachers in the prevention of traumatic dental injuries is a topic that has received a great deal of attention in recent years. However, studies conducted in different regions of the world have demonstrated that teachers and other lay people’s knowledge about traumatic dental injuries is inadequate and their behavior does not contribute to reduce the sequelae. Aim The purpose of this study was to evaluate the knowledge of school teachers about dental trauma and its management in Kannur district. Materials and Methods The survey was conducted under the Department of Paedodontics and Preventive Dentistry; Kannur Dental College among 303 school teachers randomly selected from 16 schools. Four schools were selected from 16 schools using stratified cluster sampling technique. A cross sectional study design was used. A stratified cluster sampling method was done to select the study subjects. The nature and purpose of the study was first explained to the teachers in local language. Following this the printed questionnaire was distributed to school teachers. The questionnaire was prepared based on the needs of the study after referring similar questionnaires used in studies conducted in different parts of the world. Results A statistically significant association was found between the teacher’s knowledge regarding trauma and their teaching experience. Out of the total school teachers who participated in the study, 90.1% responded correctly that the teeth most frequently affected by traumatic accidents are the upper front teeth. Nearly 23.4% responded correctly regarding management of traumatic tooth fracture. Almost 46.5% had correct knowledge regarding the reimplantation of avulsed permanent teeth. Only 14.2% responded correctly to the proper storage medium for avulsed teeth. Conclusion It was concluded from the study that among the school teachers surveyed there was significantly very low knowledge of emergency management of dental trauma. PMID:28384971

An Efficient Alternative Mixed Randomized Response Procedure

ERIC Educational Resources Information Center

Singh, Housila P.; Tarray, Tanveer A.

2015-01-01

In this article, we have suggested a new modified mixed randomized response (RR) model and studied its properties. It is shown that the proposed mixed RR model is always more efficient than the Kim and Warde's mixed RR model. The proposed mixed RR model has also been extended to stratified sampling. Numerical illustrations and graphical…

Mechanisms of Learning Transfer in Adventure Education: Qualitative Results from the NOLS Transfer Survey

ERIC Educational Resources Information Center

Sibthorp, Jim; Furman, Nate; Paisley, Karen; Gookin, John; Schumann, Scott

2011-01-01

Transfer of learning from adventure programs remains of critical interest to adventure education professionals. Although some research has investigated what transfers, notably less has focused on mechanisms that might influence transfer. This paper explores the mechanisms of transfer reported by a stratified random sample of National Outdoor…

ASSESSMENT OF THE WRITTEN LANGUAGE OF DEAF STUDENTS.

ERIC Educational Resources Information Center

MARKS, CLAUDE H.; STUCKLESS, E. ROSS

THIS INVESTIGATION WAS CONDUCTED TO DESCRIBE THE WRITTEN LANGUAGE OF DEAF STUDENTS BETWEEN 10 AND 18 YEARS OF AGE IN TERMS OF SIX MEASURABLE VARIABLES, AND TO RELATE THESE VARIABLES TO TEACHER JUDGMENTS OF QUALITY OF LANGUAGE. TEN STRATIFIED RANDOM SAMPLES OF COMPOSITIONS BY DEAF STUDENTS WERE SELECTED FROM 14 RESIDENTIAL AND DAY EDUCATIONAL…

The Effects of Grouping Practices and Curricular Adjustments on Achievement

ERIC Educational Resources Information Center

Tieso, Carol

2005-01-01

The purpose of this study was to examine the effects of curricular (textbook, revised, and differentiated) and grouping (whole, between, and within-class) practices on intermediate students' achievement in mathematics. A pretest-posttest, quasi-experimental design using a stratified random sample of 31 teachers and their students (N = 645) was…

14 CFR Sec. 19-7 - Passenger origin-destination survey.

Code of Federal Regulations, 2010 CFR

2010-01-01

... (for the carrier's internal controls). The Survey data are taken from the coupon that is lifted by a... already recorded and reported the data, in which instance the ticket coupon is non-reportable for the...). This procedure yields a “two-tiered” stratified sample. Group tickets are included on the basis of a 10...

Collaborative Job Training in Rural Areas

ERIC Educational Resources Information Center

Green, Gary Paul; Galetto, Valeria; Haines, Anna

2003-01-01

We examine collaborative efforts by employers to provide job training in rural areas and assess how this collaboration affects the willingness of employers to train workers. Data are drawn from a telephone survey conducted in 2001 of a stratified random sample of 1,590 nonmetropolitan firms in the U.S. The literature on job training suggests that…

Private Sector Views of Vocational Education: A Statewide Employer Survey.

ERIC Educational Resources Information Center

Owens, Thomas R.; Monthey, Wanda

A study examined the views of private sector employers in Oregon on vocational education. During the study, researchers mailed questionnaires to a stratified random sample of 1,500 employers throughout Oregon. In addition, they surveyed another 140 employers who were identified as hiring the largest numbers of vocational education completers in…

Impact of Teachers' Beliefs on Mathematics Education

ERIC Educational Resources Information Center

Bayaga, Anass; Wadesango, Newman; Wadesango, Ongayi Vongai

2015-01-01

The objective of the current study was to analyse the impact of teachers' personal theory and beliefs (PTB) towards Mathematics teaching. A total of 183 respondents were involved in this study, using the stratified random sampling method with Cronbach's alpha of 0.87. Due to the objective of the research and the hypothesis, it was positioned…

Cultural Diversity of Los Angeles County Residents Using Undeveloped Natural Areas

Treesearch

Patrick T. Tierney; Rene F. Dahl; Chavez Deborah J.

1998-01-01

A model of ethnic participation at undeveloped natural areas was developed and tested. The proposed model included the constructs of socio-economic status, perceived discrimination, assimilation, and ethnicity. Undeveloped natural areas were defined as being located outside of cities and primarily natural in composition. A telephone survey of a stratified random sample...

Self-Efficacy, Scripts of Love and Intention To Use Condoms among Norwegian Adolescents.

ERIC Educational Resources Information Center

Kvalem, Ingela Lundin; Traeen, Bente

2000-01-01

Studied contraceptive self-efficacy and the intention to use condoms in a stratified sample of 920 Norwegian adolescents aged 16 to 20 years. Results show that contraceptive self-efficacy in the Norwegian context is multidimensional. Discusses gender differences in planning for contraceptive use. Highlights the importance of anchoring health…

Multimedia Usage among Islamic Education Lecturers at Higher Education Institution

ERIC Educational Resources Information Center

Hamzah, Mohd Isa; Rinaldi; Razak, Khadijah Abdul

2014-01-01

This study aims to examine the level of multimedia usage among Islamic education lecturers at higher education institutions in West Sumatera, Indonesia. The participants were chosen from three types of higher institutions by using stratified random sampling. The data was collected from 250 students using questionnaires. The findings showed that…

Welfare Careers and Low Wage Employment.

ERIC Educational Resources Information Center

Miller, Joe A.; Ferman, Louis A.

A sample of 1010 low-wage workers in Detroit (stratified by sex and welfare status) were interviewed in 1969. Data were collected on background characteristics, labor market experiences, and work career histories. The data relate to sexism as an important determinant of income in low-wage groups (women earn less and have lower status jobs),…

Training Objectives, Transfer, Validation and Evaluation: A Sri Lankan Study

ERIC Educational Resources Information Center

Wickramasinghe, Vathsala M.

2006-01-01

Using a stratified random sample, this paper examines the training practices of setting objectives, transfer, validation and evaluation in Sri Lanka. The paper further sets out to compare those practices across local, foreign and joint-venture companies based on the assumption that there may be significant differences across companies of different…

Expenditures for Scientific Research Equipment at Ph.D. Granting Institutions, FY 1978.

ERIC Educational Resources Information Center

Gomberg, Irene L.; Atelsek, Frank J.

At the request of the National Science Foundation (NSF), the Higher Education Panel (a stratified sample of 760 colleges and universities) collected information on the level of institutional expenditures for research equipment, the federal contribution to those expenditures, and the share of funds expended for high-cost items. The data were…

Job Demand in the Cosmetology Industry.

ERIC Educational Resources Information Center

Rudner, Lawrence M.; Deutermann, William V., Jr.

In order to determine job demand in the cosmetology industry, a survey was made of a nationally representative stratified random sample of 1,454 beauty salons, barber shops, and unisex salons in July 1991. Salon owners were asked about 1990 and their plans for the future. Survey results were supplemented with information about the industry…

An Investigation of Middle School Students' Attitudes and Awareness of Water Use

ERIC Educational Resources Information Center

Aydogdu, Bülent; Çakir, Aysun

2016-01-01

The purpose of this mixed method study is to investigate middle school students' attitudes and awareness of water use. The quantitative data were collected through the administration of "Water Usage Questionnaire (WUQ)". The qualitative data were collected through semi structured interviews. In the study the stratified sampling method…

Recruitment to Teaching: Career Expectations of South Carolina Young People.

ERIC Educational Resources Information Center

Lyson, Thomas A.

Using data collected from a stratified random sample of South Carolina high school seniors in 1969, the study compared the patterns of occupational choices among white and black boys and girls, and examined the relationship among race, sex, and teacher recruitment. Social class origin, local residence place, and scholastic performance were…

Workforce Improvement Network 2000 Survey of Virginia Employers.

ERIC Educational Resources Information Center

Foucar-Szocki, Diane; Bolt, Les

A stratified random sample of Virginia's 4,000 employers with over 100 employees was surveyed about workplace-based foundational basic skills (oral and written communication, reading, math, thinking skills, teamwork, English proficiency, and basic computer literacy). A total of 446 surveys were sent with a usable response rate of 18 percent.…

The Learning Behaviors Scale: National Standardization in Trinidad and Tobago

ERIC Educational Resources Information Center

Chao, Jessica L.; McDermott, Paul A.; Watkins, Marley W.; Drogalis, Anna Rhoad; Worrell, Frank C.; Hall, Tracey E.

2018-01-01

This study reports on the national standardization and validation of the Learning Behaviors Scale (LBS) for use in Trinidad and Tobago. The LBS is a teacher rating scale centering on observable behaviors relevant to identifying childhood approaches to classroom learning. Teachers observed a stratified sample of 900 students across the islands'…

Evaluation of LEAA Funded Courts Training Programs. Volume I.

ERIC Educational Resources Information Center

McManis Associates, Inc., Washington, DC.

An impact evaluation of eight courts training project (CTP) institutes funded by the Law Enforcement Assistance Administration was conducted. After a literature search and visits to potential evaluation sites in all fifty states, twelve sites were selected from a random stratified sample of court systems. Data were obtained from 1047 respondents…

Social Strain, Self-Control, and Juvenile Gambling Pathology: Evidence From Chinese Adolescents

ERIC Educational Resources Information Center

Cheung, Nicole W. T.

2016-01-01

Despite recent concerns over youthful problem gambling, few gambling studies have looked into Asian adolescent populations. This study of a stratified, random sample of high school students in Hong Kong is designed to estimate the prevalence of gambling pathology among Chinese adolescents and to examine the relationships between social strain,…

Effect of School Policy on Tobacco Use by School Personnel in Bihar, India.

ERIC Educational Resources Information Center

Sinha, Dhirendra N.; Gupta, Prakash C.; Warren, Charles W.; Asma, Samira

2004-01-01

This study examined the relationship between school tobacco policies and tobacco use prevalence among school personnel. Two subsets of schools were identified in Bihar, India: Federal schools (with a tobacco policy), and State schools (without a tobacco policy). Stratified probability samples of 50 schools each were selected. The survey was…

An Employer Needs Assessment for Vocational Education.

ERIC Educational Resources Information Center

Muraski, Ed J.; Whiteman, Dick

An employer needs assessment study was performed at Porterville College (PC), in California in 1991 as part of a comprehensive educational planning process for PC and the surrounding area. A validated survey instrument was sent to a stratified random sampling of 593 employers in the community, asking them to provide general information about their…

Screening and Brief Intervention for Tobacco Use by Student Health Providers on College Campuses

ERIC Educational Resources Information Center

Sutfin, Erin L.; McNamara, Robert S.; Blocker, Jill N.; Ip, Edward H.; O'Brien, Mary Claire; Wolfson, Mark

2012-01-01

Objective: This study assessed college students' reports of tobacco screening and brief intervention by student health center providers. Participants: Participants were 3,800 students from 8 universities in North Carolina. Methods: Web-based survey of a stratified random sample of undergraduates. Results: Fifty-three percent reported ever visiting…

The King Pre-Retirement Checklist: Assessing Differences in Pre-Retirement Planning.

ERIC Educational Resources Information Center

Zitzow, Darryl; King, Donald N.

In an effort to assess the retirement preparedness of Midwestern populations above the age of 28, the King Pre-Retirement Checklist was administered to a sampling of 458 persons randomly selected and proportionally stratified by geographic location and community size. Factors examined were financial, social, family cohesion, mobility/health,…

Factors Influencing Federal Employee Worker Satisfaction: A Baseline Study.

ERIC Educational Resources Information Center

Schmidt, Wallace V.; And Others

Utilizing data from the Federal Employee Attitude Survey, 1979, a survey was distributed to a stratified random sample of 20,000 employees to identify and analyze the factors influencing federal employee worker satisfaction. Questions on the survey ranged from demographics to personal evaluations of the work environment as recorded on a…

School Instructional Climate and Student Achievement: An Examination of Group Norms for Differentiated Instruction

ERIC Educational Resources Information Center

Goddard, Yvonne; Goddard, Roger; Kim, Minjung

2015-01-01

The purpose of this article is to investigate the relationship between school instructional climate and students' fifth-grade mathematics and reading achievement, with a particular emphasis on norms for practice consistent with differentiated instruction. Using data from a stratified random sample of Michigan elementary schools, we employed…

Secondary School Science and Mathematics Teachers, Characteristics and Service Loads.

ERIC Educational Resources Information Center

Mills, Thomas J.

Determined were the educational and professional backgrounds, and some aspects of the operational environment of teachers of secondary school science and mathematics (Grades 7-12) in the public and private schools of the United States during the school year 1960-61. A stratified random sampling method was used to ensure proportional representation…

An Employer Needs Assessment for Vocational Education: Palomar Community College District.

ERIC Educational Resources Information Center

Muraski, Ed J.; Barker, Cherie

A study was conducted to determine the employment needs within the Palomar Community College District. Surveys were mailed to a stratified random sample of 600 North San Diego County employers, requesting respondents to provide information on type and size of business, to rank the occupational programs offered by Palomar according to employment…

Influences on Students Selecting Cooperative Education Programs in Michigan High Schools. Final Report.

ERIC Educational Resources Information Center

Woloszyk, Carl A.

Factors influencing the decision of high school students to enroll in cooperative education programs were investigated in a survey. The stratified random sample consisted of 275 high school students currently enrolled in cooperative education programs in five different types of communities throughout Michigan. The survey questionnaire included 8…

Maneuvering the Role as a Community College Artist-Educator: Scholarship Assessed

ERIC Educational Resources Information Center

Gibson, John R.; Murray, John P.

2009-01-01

This study examined how Texas community college artist-educators balance artistic productivity with their teaching responsibilities. The 98 survey respondents represented 76.6% of a stratified random sample of the full-time instructors in visual arts departments within the 50 Texas public community college districts. Access to studio space and…

Impact Evaluation of Further Mathematics Curriculum in Nigeria

ERIC Educational Resources Information Center

Odili, Godwin Alo; Asuru, Vincent A.

2011-01-01

This research was a perceptual survey study carried out to determine whether the goals of Further Mathematics Curriculum (FMC) are being achieved at the Senior Secondary School level. The sample for the study consisted of 240 FM final year students, 45 FM teachers and 180 undergraduates who were selected by a multistage stratified random sampling…

Relations between Parental Psychological Control and Childhood Relational Aggression: Reciprocal in Nature?

ERIC Educational Resources Information Center

Kuppens, Sofie; Grietens, Hans; Onghena, Patrick; Michiels, Daisy

2009-01-01

Using a cross-lagged panel design, this study examined the directionality of relations between parental psychological control and child relational aggression. Data were collected from a proportionally stratified sample of 600 Flemish 8- to 10-year-old children at 3 measurement points with 1-year intervals. Reciprocal effects were evident in…

Elementary School Parent Engagement Efforts: Relations with Educator Perceptions and School Characteristics

ERIC Educational Resources Information Center

McDowall, Philippa S.; Schaughency, Elizabeth

2017-01-01

School efforts to engage parents are posited to influence whether and how they are involved in their children's schooling. The authors examined educators' engagement efforts in beginning reading, their subjective evaluations of engagement practices, and beliefs about parent involvement, in two stratified samples of New Zealand elementary school…

AIP Report, 1989 Salaries: Society Membership Survey.

ERIC Educational Resources Information Center

Kellman, Dawn; Scholz, Catherine

This report examines the variations in salaries by degree level, employment sector, geographic location, and work activity among members of the scientific labor force and educational system. The data are based on a stratified random sample of one-sixth of the U.S. membership of the American Institute of Physics Member Societies; approximately…

Understanding the Priorities of Australian Secondary Schools through an Analysis of Their Mission and Vision Statements

ERIC Educational Resources Information Center

Allen, Kelly-Ann; Kern, Margaret L.; Vella-Brodrick, Dianne; Waters, Lea

2018-01-01

Purpose: The vision or mission statement of a school outlines the school's purpose and defines the context, goals, and aspirations that govern the institution. Using vision and mission statements, the present descriptive research study investigated trends in Australian secondary schools' priorities. Research Methods: A stratified sample of…

Factors Influencing Entrepreneurial Intentions of Chinese Secondary School Students: An Empirical Study

ERIC Educational Resources Information Center

Xu, Xiaozhou; Ni, Hao; Ye, Yinghua

2016-01-01

The ideal stage to learn about and foster positive attitudes toward entrepreneurship is believed to be during childhood and adolescence. However, most entrepreneurial studies examine college rather than secondary school students (SSS). Based on a modified theory of planned behavior (TPB), this study used stratified cluster sampling and a…

Public-Private Partnership and Infrastructural Development in Nigerian Universities

ERIC Educational Resources Information Center

Oduwaiye, R. O.; Sofoluwe, A. O.; Bello, T. O.; Durosaro, I. A.

2014-01-01

This study investigated the degree to which Public-Private Partnership (PPP) services are related to infrastructural development in Nigerian Universities. The research design used was descriptive survey method. The population for the study encompassed all the 20 universities in South-west Nigeria. Stratified random sampling was used to select 12…

The Social Correlates of Lexical Borrowing in Spanish in New York City

ERIC Educational Resources Information Center

Varra, Rachel Marie

2013-01-01

This dissertation investigates lexical borrowing in Spanish in New York. English-origin lexical material was extracted from a stratified sample of 146 Spanish-speaking informants of different ages, national origins, classes, etc., living in New York City. ANOVAs and Pearson correlations determined whether lexical borrowing frequency and the type…

The Role of Religiosity in Influencing Adolescent and Adult Alcohol Use in Trinidad

ERIC Educational Resources Information Center

Rollocks, Steve C. T.; Dass, Natasha; Seepersad, Randy; Mohammed, Linda

2008-01-01

This study examined the role of religiosity among adolescents' and adults' alcohol use in Trinidad. A stratified random sample design of 369 adolescents and 210 adult parents belonging to the various religious groups in Trinidad was employed. Participants were randomly selected from various educational districts across Trinidad. Adolescent…

Missed Opportunities to Keep Children Safe? National Survey of Injury Prevention Activities of Children's Centres

ERIC Educational Resources Information Center

Watson, Michael Craig; Mulvaney, Caroline; Timblin, Clare; Stewart, Jane; Coupland, Carol A.; Deave, Toity; Hayes, Mike; Kendrick, Denise

2016-01-01

Objective: To ascertain the activities undertaken by children's centres to prevent unintentional injuries in the under-fives and, in particular, the prevention of falls, poisoning and scalds. Design: A questionnaire was posted to managers of 851 children's centres, using stratified cluster sampling. The questionnaire included questions on injury…

Cigarette Smoking and Anti-Smoking Counseling Practices among Physicians in Wuhan, China

ERIC Educational Resources Information Center

Gong, Jie; Zhang, Zhifeng; Zhu, Zhaoyang; Wan, Jun; Yang, Niannian; Li, Fang; Sun, Huiling; Li, Weiping; Xia, Jiang; Zhou, Dunjin; Chen, Xinguang

2012-01-01

Purpose: The paper seeks to report data on cigarette smoking, anti-smoking practices, physicians' receipt of anti-smoking training, and the association between receipt of the training and anti-smoking practice among physicians in Wuhan, China. Design/methodology/approach: Participants were selected through the stratified random sampling method.…

Student Teaching in the United States. Executive Summary

ERIC Educational Resources Information Center

National Council on Teacher Quality, 2011

2011-01-01

In an effort to understand what makes a student teaching experience strong, the National Council on Teacher Quality (NCTQ) has undertaken this comprehensive review. Over a period of two years, NCTQ researchers examined the student teaching programs of a stratified random sample of 134 higher education institutions across the United States, with at…

Effects of spatial allocation and parameter variability on lakewide estimates from surveys of Lake Superior, North America’s largest lake

EPA Science Inventory

Lake Superior was sampled in 2011 using a Generalized Random Tessellation Stratified design (n=54 sites) to characterize biological and chemical properties of this huge aquatic resource, with statistical confidence. The lake was divided into two strata (inshore <100m and offsh...

An Investigation of the Difficulties Faced by EFL Undergraduates in Speaking Skills

ERIC Educational Resources Information Center

Al-Jamal, Dina A.; Al-Jamal, Ghadeer A.

2014-01-01

Since speaking well in English is crucial for English language literature undergraduates, the present study aimed at describing difficulties that may be encountered at an EFL setting. The sample was stratified random as drawn from six Jordanian public universities. Survey questionnaires as well as semi-structured interviews were constructed. 64…

Lake Superior Zooplankton Biomass Predictions from LOPC Tow Surveys Compare Well with a Probability Based Net Survey

EPA Science Inventory

We conducted a probability-based sampling of Lake Superior in 2006 and compared the zooplankton biomass estimate with laser optical plankton counter (LOPC) predictions. The net survey consisted of 52 sites stratified across three depth zones (0-30, 30-150, >150 m). The LOPC tow...

Maternal Religiosity, Family Resources and Stressors, and Parent-Child Attachment Security in Northern Ireland

ERIC Educational Resources Information Center

Goeke-Morey, Marcie C.; Cairns, Ed; Merrilees, Christine E.; Schermerhorn, Alice C.; Shirlow, Peter; Cummings, E. Mark

2013-01-01

This study explores the associations between mothers' religiosity, and families' and children's functioning in a stratified random sample of 695 Catholic and Protestant mother-child dyads in socially deprived areas in Belfast, Northern Ireland, a region which has experienced centuries of sectarian conflict between Protestant Unionists and…

Sex Roles and Perceived Job Stress of Washington Elementary Principals.

ERIC Educational Resources Information Center

Torelli, Joseph A.

The relationship between elementary principals' perceived job stress and sex role is examined. Questionnaires mailed to a random stratified sample of 200 elementary principals in Washington state (50 females, 150 males) yielded 172 useable returns, an 86 percent response rate. Two measurement instruments were used: the Bem Sex Role Inventory…

Social Capital and Community Participation among Migrant Workers in China

ERIC Educational Resources Information Center

Palmer, Neal A.; Perkins, Douglas D.; Xu, Qingwen

2011-01-01

In China, rapid development has prompted massive migration from rural to urban areas. Migrants' participation in Urban Residents Committees (URCs) and other community organizations offers opportunities for the development of social capital and democracy in contemporary China. We use 2006 survey data from a stratified convenience sample of 3,024…

Decision Processes Among the Elderly: Do They Differ?

ERIC Educational Resources Information Center

Goodchilds, Jacqueline D.; Bikson, Tora K.

Decision making processes among older adults were investigated within the context of grocery selection, using a stimulus array involving two product classes (bread and cheese) with 10 items per class. The sample (N=580) was stratified by sex, household status (living alone or with spouse), and age, employing three age groupings: 25-34 (young),…

Correlates of Home Health Care Services Use among the Elderly.

ERIC Educational Resources Information Center

Starrett, Richard A.; And Others

The use of health and social services is influenced by economic, community, geographic, organizational, societal, and environmental factors. A study was conducted to examine predisposing, enabling, and need-for-care factors related to the use of home health care services by a stratified random sample of 400 older adults. Predisposing factors…

Mitigating budget constraints on visitation volume surveys: the case of U.S. National forests

Treesearch

Ashley E. Askew; Donald B.K. English; Stanley J. Zarnoch; Neelam C. Poudyal; J.M. Bowker

2014-01-01

Stratified random sampling (SRS) provides a scientifically based estimate of a population comprising mutually exclusive, homogenous subgroups. In the National Visitor Use Monitoring (NVUM) program, SRS is used to estimate recreation visitation and visitor characteristics across activities on National forests. However, with rising costs and declining budgets, carrying...

Exploring the Impact of Applicants' Gender and Religion on Principals' Screening Decisions for Assistant Principal Applicants

ERIC Educational Resources Information Center

Bon, Susan C.

2009-01-01

In this experimental study, a national random sample of high school principals (stratified by gender) were asked to evaluate hypothetical applicants whose resumes varied by religion (Jewish, Catholic, nondenominational) and gender (male, female) for employment as assistant principals. Results reveal that male principals rate all applicants higher…

Exploring Student Understanding of Grades and Report Cards

ERIC Educational Resources Information Center

Gwidt, Kathleen M.

2010-01-01

This qualitative study was designed to identify how students from a single high school in the rural Midwest perceive grades and report cards. Stratified purposeful random sampling resulted in the inclusion of 14 students who provided journal entries and participated in one-on-one interviews for the purpose of exploring student understanding of…

Information Needs of State Directors of Vocational Education.

ERIC Educational Resources Information Center

McCracken, J. David

To identify the critical problems of state directors of vocational education and the information sources utilized by them, data were collected by mail questionnaire and a series of telephone interviews with a stratified random sample of 15 state directors. Analysis of the data with respect to major problems, methods used to seek information,…

ADHD Symptoms in Children with Mild Intellectual Disability

ERIC Educational Resources Information Center

Simonoff, Emily; Pickles, Andrew; Wood, Nicky; Gringras, Paul; Chadwick, Oliver

2007-01-01

Objectives: To determine whether the nature and correlates of attention-deficit/hyperactivity disorder (ADHD) symptoms are different in subjects with mild intellectual disability (ID) compared to subjects with average ability. Method: From a general population sample of 2,726 12- to 15-year-olds, a stratified subsample was selected to enrich for…

Reference List Accuracy in Social Work Journals: A Follow-Up Analysis

ERIC Educational Resources Information Center

Mitchell-Williams, Missy T.; Skipper, Antonius D.; Alexander, Marvin C.; Wilks, Scott E.

2017-01-01

Purpose: Following up an "Research on Social Work Practice" article published a decade ago, this study aimed to examine reference error rates among five, widely circulated social work journals. Methods: A stratified random sample of references was selected from the year 2013 (N = 500, 100/journal). Each was verified against the original…

Professional Teacher Learning in Virtual Environments

ERIC Educational Resources Information Center

Pachler, Norbert; Daly, Caroline

2006-01-01

This article is based on qualitative empirical research into the ways in which teachers view their experiences as learners in the context of an online tutor group who are studying for the mixed-mode Master of Teaching degree at the Institute of Education, University of London. Data collected from a stratified sample of teacher participants is…

Monitoring Achievement of Educational Governance/Management Policy Goals.

ERIC Educational Resources Information Center

Sederberg, Charles H.; Hendrix, Vernon L.

This paper reports on a field test of a system for monitoring the achievement of selected educational governance/management goals. The study entailed (1) collection of enrollment, revenue, expenditure, and teacher assignment data from a stratified random sample of Minnesota districts for a seven-year period, 1969-70 through 1975-76; (2) reduction…

Social Attitudes and Educational Needs of Women in the Chaffey Community College District.

ERIC Educational Resources Information Center

Lyman-Viera, Karen A.; Boggs, John

A socio-economically stratified sample of 368 randomly selected adult women residents of the Chaffey College district were interviewed to determine their demographic characteristics, educational needs and interests, perceived barriers to educational participation, and the adequacy of current college programs to meet the needs of women. Results of…

Results from an Empirical Study of School Principals' Decisions about Disclosure of HIV Status

ERIC Educational Resources Information Center

Chenneville, Tiffany

2007-01-01

Elementary school principals' decisions about disclosure of school age children's confidential medical information was empirically studied. Participants included a stratified sample of 339 elementary school principals from the seven largest school districts in Florida. Each participant received one of six vignettes describing a student with HIV,…

Teachers' Attitude towards Implementation of Learner-Centered Methodology in Science Education in Kenya

ERIC Educational Resources Information Center

Ndirangu, Caroline

2017-01-01

This study aims to evaluate teachers' attitude towards implementation of learner-centered methodology in science education in Kenya. The study used a survey design methodology, adopting the purposive, stratified random and simple random sampling procedures and hypothesised that there was no significant relationship between the head teachers'…

Early Adolescent Outcomes of Institutionally Deprived and Non-Deprived Adoptees. III. Quasi-Autism

ERIC Educational Resources Information Center

Rutter, Michael; Kreppner, Jana; Croft, Carla; Murin, Marianna; Colvert, Emma; Beckett, Celia; Castle, Jenny; Sonuga-Barke, Edmund

2007-01-01

Background: Some young children reared in profoundly depriving institutions have been found to show autistic-like patterns, but the developmental significance of these features is unknown. Methods: A randomly selected, age-stratified, sample of 144 children who had experienced an institutional upbringing in Romania and who were adopted by UK…

Assessment of the Implementation of Continuous Assessment: The Case of METTU University

ERIC Educational Resources Information Center

Walde, Getinet Seifu

2016-01-01

This paper examines the status of the implementation of continuous assessment (CA) in Mettu University. A random stratified sampling method was used to select 309 students and 29 instructors and purposive method used to select quality assurance and faculty Deans. Questionnaires, focus group discussion, interview and documents were used for data…