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Articles 16531 - 16560 of 21191

Full-Text Articles in Social and Behavioral Sciences

A Comparison Of Eight Shrinkage Formulas Under Extreme Conditions, David A. Walker May 2007

A Comparison Of Eight Shrinkage Formulas Under Extreme Conditions, David A. Walker

Journal of Modern Applied Statistical Methods

The performance of various shrinkage formulas for estimating the population squared multiple correlation coefficient (ρ2) were compared under extreme conditions often found in educational research with small sample sizes of 10, 15, 20, 25, 30 and regressor variates ranging from 2 to 4. A new formula for estimating ρ2, Adj R2 DW, was examined in terms of its performance under various conditions of N, p, ρ2, along with its bias properties and standard error estimates. The two shrinkage formulas that performed most consistently were the Claudy (Adj R2 C) and Walker (Adj R2 DW)

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Examining Cronbach Alpha, Theta, Omega Reliability Coefficients According To Sample Size, Ilker Ercan, Berna Yazici, Deniz Sigirli, Bulent Ediz, Ismet Kan May 2007

Examining Cronbach Alpha, Theta, Omega Reliability Coefficients According To Sample Size, Ilker Ercan, Berna Yazici, Deniz Sigirli, Bulent Ediz, Ismet Kan

Journal of Modern Applied Statistical Methods

Differentiations according to the sample size of different reliability coefficients are examined. It is concluded that the estimates obtained by Cronbach alpha and teta coefficients are not related with the sample size, even the estimates obtained from the small samples can represent the population parameter. However, the Omega coefficient requires large sample sizes.

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Analyses Of Unbalanced Groups-Versus-Individual Research Designs Using Three Alternative Approximate Degrees Of Freedom Tests: Test Development And Type I Error Rates, Stephanie Wehry, James Algina May 2007

Analyses Of Unbalanced Groups-Versus-Individual Research Designs Using Three Alternative Approximate Degrees Of Freedom Tests: Test Development And Type I Error Rates, Stephanie Wehry, James Algina

Journal of Modern Applied Statistical Methods

Three approximate degrees of freedom quasi-F tests of treatment effectiveness were developed for use in research designs when one treatment is individually delivered and the other is delivered to individuals nested in groups of unequal size. Imbalance in the data was studied from the prospective of subject attrition. The results indicated the test that best controls the Type I error rate depends on the number of groups in the group-administered treatment but does not depend on the subject attrition rates included in the study.

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Another Look At The Confidence Intervals For The Noncentral T Distribution, Bruno Lecoutre May 2007

Another Look At The Confidence Intervals For The Noncentral T Distribution, Bruno Lecoutre

Journal of Modern Applied Statistical Methods

An alternative approach to the computation of confidence intervals for the noncentrality parameter of the Noncentral t distribution is proposed. It involves the percent points of a statistical distribution. This conceptual improvement renders the technical process for deriving the limits more comprehensible. Accurate approximations can be derived and easily used.

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Better Binomial Confidence Intervals, James F. Reed Iii May 2007

Better Binomial Confidence Intervals, James F. Reed Iii

Journal of Modern Applied Statistical Methods

The construction of a confidence interval for a binomial parameter is a basic analysis in statistical inference. Most introductory statistics textbook authors present the binomial confidence interval based on the asymptotic normality of the sample proportion and estimating the standard error - the Wald method. For the one sample binomial confidence interval the Clopper-Pearson exact method has been regarded as definitive as it eliminates both overshoot and zero width intervals. The Clopper-Pearson exact method is the most conservative and is unquestionably a better alternative to the Wald method. Other viable alternatives include Wilson's Score, the Agresti-Coull method, and the Borkowf …

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A Spline-Based Lack-Of-Fit Test For Independent Variable Effect, Chin-Shang Li, Wanzhu Tu May 2007

A Spline-Based Lack-Of-Fit Test For Independent Variable Effect, Chin-Shang Li, Wanzhu Tu

Journal of Modern Applied Statistical Methods

In regression analysis of count data, independent variables are often modeled by their linear effects under the assumption of log-linearity. In reality, the validity of such an assumption is rarely tested, and its use is at times unjustifiable. A lack-of-fit test is proposed for the adequacy of a postulated functional form of an independent variable within the framework of semiparametric Poisson regression models based on penalized splines. It offers added flexibility in accommodating the potentially non-loglinear effect of the independent variable. A likelihood ratio test is constructed for the adequacy of the postulated parametric form, for example log-linearity, of the …

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A Comparison Of One-High-Threshold And Two-High-Threshold Multinomial Models Of Source Monitoring, Mahesh Menon, Todd S. Woodward May 2007

A Comparison Of One-High-Threshold And Two-High-Threshold Multinomial Models Of Source Monitoring, Mahesh Menon, Todd S. Woodward

Journal of Modern Applied Statistical Methods

A data simulation study comparing the one-high-threshold (1HT) and two-high-threshold (2HT) multinomial models suggested that 2HT models are more likely to misestimate the underlying parameter values, due to inflation of some parameters (b and d), and deflation of others (D).

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Multinomial Logistic Regression Model For The Inferential Risk Age Groups For Infection Caused By Vibrio Cholerae In Kolkata, India, Krishnan Rajendran, Thandavarayan Ramamurthy, Dipika Sur May 2007

Multinomial Logistic Regression Model For The Inferential Risk Age Groups For Infection Caused By Vibrio Cholerae In Kolkata, India, Krishnan Rajendran, Thandavarayan Ramamurthy, Dipika Sur

Journal of Modern Applied Statistical Methods

Multinomial Logistic Regression (MLR) modeling is an effective approach for categorical outcomes, as compared with discriminant function analysis and log-linear models for profiling individual category of dependent variable. To explore the yearly change of inferential age groups of acute diarrhoeal patients infected with Vibrio cholerae during 1996-2000 by MLR, systematic sampling data were generated from an active surveillance study. Among 1330 V.cholerae infected cases, the predominant age category was up to 5 years accounting for 478 (30.5%) cases. The independent variables V.cholerae O1 (p<0.001) and non-O1 and non-O139 (p < 0.001) were significantly associated with children under 5 years age group. V.cholerae O139 inferential age group was > 40 years. The infection mediated by V.cholerae O1 had significantly decreasing trend Exp(B) year wise from …

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Estimation Of Risk For Developing Cardiac Problem In Patients Of Type 2 Diabetes As Obtained By The Technique Of Density Estimation, Ajit Mukherjee, Ajit Mathur, Rakesh Mittal May 2007

Estimation Of Risk For Developing Cardiac Problem In Patients Of Type 2 Diabetes As Obtained By The Technique Of Density Estimation, Ajit Mukherjee, Ajit Mathur, Rakesh Mittal

Journal of Modern Applied Statistical Methods

High levels of cholesterol and triglyceride are known to be strongly associated with development of cardiac problem in patients of type 2 diabetes. In a hospital-based study, patients showing ECG positive were compared with those who were not. The observations on cholesterol and triglyceride were considered for estimation of risk for developing the cardiac problem. The technique of density estimation employing Epanechnikov kernel was used for estimating bivariate probability density functions with respect to observations on cholesterol and triglyceride of the two groups. Using the odds form of Bayes’ rule, the estimates of posterior odds were computed.

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The Open Archives Initiative, Michael L. Nelson May 2007

The Open Archives Initiative, Michael L. Nelson

Computer Science Presentations

PDF of a powerpoint presentation from the Open Archives Initiative DRIADE ( Digital Repository of Information and Data for Evolution) Workshop, Durham, North Carolina, May 16-17, 2007. Also available on Slideshare.

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An Analysis Of Key Aspects Of Warm And Cool Season Flash Flooding In The Southern Appalachians, William Baldwin May 2007

An Analysis Of Key Aspects Of Warm And Cool Season Flash Flooding In The Southern Appalachians, William Baldwin

Masters Theses & Specialist Projects

Flash flooding kills more people in the United States than any other severe weather phenomenon. One of the most vulnerable areas for flooding is the southern Appalachians. These mountains lie in a geographical location that places them near the Atlantic Ocean and the Gulf of Mexico, two major moisture source regions. This ample supply of moisture, mid-latitude circulation patterns, and orographic lifting leads to annual precipitation totals in the southern Appalachians that are comparable to locations along the Gulf coast. The present study investigates eight non-tropical flash flood events. Four of the events occurred in the cool season and four …

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Semantic Web: Technologies And Applications For The Real-World, Amit P. Sheth May 2007

Semantic Web: Technologies And Applications For The Real-World, Amit P. Sheth

Kno.e.sis Publications

No abstract provided.

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Visualization Of Events In A Spatially And Multimedia Enriched Virtual Environment, Leonidas Deligiannidis, Farshad Hakimpour, Amit P. Sheth May 2007

Visualization Of Events In A Spatially And Multimedia Enriched Virtual Environment, Leonidas Deligiannidis, Farshad Hakimpour, Amit P. Sheth

Kno.e.sis Publications

Semantic Event Tracker (SET) is a highly interactive visualization tool for tracking and associating activities (events) in a spatially and Multimedia Enriched Virtual Environment. SET provides integrated views of information spaces while providing overview and detail to improve perception and evaluation of complex scenarios. We model an event as an object that describes an action and its location, time, and relations to other objects. Real world event information is extracted from Internet sources, then stored and processed using Semantic Web technologies that enable us to discover semantic associations between events. We use RDF graphs to represent semantic metadata and ontologies. …

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An Experiment In Integrating Large Biomedical Knowledge Resources With Rdf: Application To Associating Genotype And Phenotype Information, Satya S. Sahoo, Olivier Bodenreider, Kelly Zeng, Amit P. Sheth May 2007

An Experiment In Integrating Large Biomedical Knowledge Resources With Rdf: Application To Associating Genotype And Phenotype Information, Satya S. Sahoo, Olivier Bodenreider, Kelly Zeng, Amit P. Sheth

Kno.e.sis Publications

Bridging between genotype and phenotype is generally achieved through the integration of knowledge sources such as Entrez Gene (EG), Online Mendelian Inheritance in Man (OMIM) and the Gene Ontology (GO). Traditionally, such integration implies manual effort or the development of customized software. In this paper, we demonstrate how the Resource Description Framework (RDF) can be used to represent and integrate these resources and support complex queries over the unified resource. We illustrate the effectiveness of our approach by answering a real-world biomedical query linking a specific molecular function, glycosyltransferase, to the disorder congenital muscular dystrophy, which potentially forms a new …

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Spatio-Temporal Analysis Of Observed Soil Moisture From Nebraska, Ashley Littell May 2007

Spatio-Temporal Analysis Of Observed Soil Moisture From Nebraska, Ashley Littell

Masters Theses & Specialist Projects

Soil moisture is a measure of the water content in a soil that is dependent upon precipitation, evapotranspiration, runoff, drainage, and irrigation. Nebraska is one of the few states that measures soil moisture in an extensive network that records weather variables on a daily basis. Daily soil moisture observations are collected from depths of 10, 25, 50, and 100 centimeters and analyzed in this research. Data from these stations are evaluated on the spatial and temporal scales using spatial interpolations, time-series analysis, and cross-correlations to better understand the variations of soil moisture in the Northern Great Plains. Spatial interpolation grids …

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Modeling Of Culicidae Population Capacity Using Remote Sensing, Gis, And Fractal Geometry, Daniel Patrick Johnson May 2007

Modeling Of Culicidae Population Capacity Using Remote Sensing, Gis, And Fractal Geometry, Daniel Patrick Johnson

All-Inclusive List of Electronic Theses and Dissertations

A remote sensing and fractal geometric approach is proposed for the surveillance of mosquito population. The spread of vector-borne pathogens is becoming increasingly important with recent discussions of extensive human urbanization and global climate change. To date most studies dealing with mosquito transmitted disease surveyed by remote sensing and Geographic Information Systems have been conducted in tropical homogenous locales. This study approached the issue in a rapidly suburbanizing county in the Midwestern portion of the United States. Adult mosquitoes were trapped over a several year period and the landscape of the surrounding patches analyzed via remote sensing, fractal geometry, and …

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Modeling Environmental Justice: A Comparative Analysis Of Multiple Environmental Metrics, Trevor K. Fuller May 2007

Modeling Environmental Justice: A Comparative Analysis Of Multiple Environmental Metrics, Trevor K. Fuller

All-Inclusive List of Electronic Theses and Dissertations

Environmental justice, the study of interactions between environmental disamenities and socioeconomic conditions, has been a focus of policy debates and research since the late 1970s. To date, environmental justice research has relied heavily on a few selected metrics, including, but not limited to, Toxics Release Inventory (TRI), Treatment, Storage, and Disposal Facilities (TSDF), and Super.fund site Jocations. In this study, I will examine the efficacy of these environmental quality datasets, as well as that oflocal blood-lead level data (in children), to predict observed socioeconomic conditions and compare these results to an emerging metric, normalized difference vegetation index (NDVI). Based on …

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Effects Of Physical Activity On Psychological Change In Advanced Age: A Multivariate Meta-Analysis, Meng-Jia Wu, Betsy Jane Becker, Yael Netz May 2007

Effects Of Physical Activity On Psychological Change In Advanced Age: A Multivariate Meta-Analysis, Meng-Jia Wu, Betsy Jane Becker, Yael Netz

Journal of Modern Applied Statistical Methods

An example of multivariate meta-analysis is demonstrated by synthesizing the treatment effects of exercise of 15 groups on six mood state changes in elders measured by the Profile of Mood States (POMS) scale. Two different methods were used to analyze this multivariate dataset. The SAS codes for two set of the analyses were provided. Results showed that exercise has a modest and positive impact on elders mood change.

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Application Of A New Procedure For Power Analysis And Comparison Of The Adjusted Univariate And Multivariate Tests In Repeated Measures Designs, Sean W. Mulvenon, M. Austin Betz, Kening Wang, Bruno D. Zumbo May 2007

Application Of A New Procedure For Power Analysis And Comparison Of The Adjusted Univariate And Multivariate Tests In Repeated Measures Designs, Sean W. Mulvenon, M. Austin Betz, Kening Wang, Bruno D. Zumbo

Journal of Modern Applied Statistical Methods

A relationship between the multivariate and univariate noncentrality parameters in repeated measures designs was developed for the purpose of assessing the relative power of the univariate and multivariate approaches. An application is provided examining the use of repeated measures designs to evaluate student achievement in a K-12 school system

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The Effects Of Heteroscedasticity On Tests Of Equivalence, Jamie A. Gruman, Robert A. Cribbie, Chantal A. Arpin-Cribbie May 2007

The Effects Of Heteroscedasticity On Tests Of Equivalence, Jamie A. Gruman, Robert A. Cribbie, Chantal A. Arpin-Cribbie

Journal of Modern Applied Statistical Methods

Tests of equivalence, which are designed to assess the similarity of group means, are becoming more popular, yet very little is known about the statistical properties of these tests. Monte Carlo methods are used to compare the test of equivalence proposed by Schuirmann with modified tests of equivalence that incorporate a heteroscedastic error term. It was found that the latter were more accurate than the Schuirmann test in detecting equivalence when sample sizes and variances were unequal.

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On The Properties Of Beta-Gamma Distribution, Lingji Kong, Carl Lee, J.H. Sepanski May 2007

On The Properties Of Beta-Gamma Distribution, Lingji Kong, Carl Lee, J.H. Sepanski

Journal of Modern Applied Statistical Methods

A class of generalized gamma distribution called the beta-gamma distribution is proposed. Some of its properties are examined. Its shape can be reversed J-shaped, unimodal, or bimodal. Reliability and hazard functions are also derived, and applications are discussed.

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On The Product Of Maxwell And Rice Random Variables, M. Shakil, B. M. Golam Kibria May 2007

On The Product Of Maxwell And Rice Random Variables, M. Shakil, B. M. Golam Kibria

Journal of Modern Applied Statistical Methods

The distributions of the product of independent random variables arise in many applied problems. These have been extensively studied by many researchers. In this paper, the exact distributions of the product |XY| have been derived when X and Y are Maxwell and Rice random variables respectively, and are distributed independently of each other. The associated cdfs, pdfs, and kth moments have been given.

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Optimal Lp-Metric For Minimizing Powered Deviations In Regression, Stan Lipovetsky May 2007

Optimal Lp-Metric For Minimizing Powered Deviations In Regression, Stan Lipovetsky

Journal of Modern Applied Statistical Methods

Minimizations by least squares or by least absolute deviations are well known criteria in regression modeling. In this work the criterion of generalized mean by powered deviations is suggested. If the parameter of the generalized mean equals one or two, the fitting corresponds to the least absolute or the least squared deviations, respectively. Varying the power parameter yields an optimum value for the objective with a minimum possible residual error. Estimation of a most favorable value of the generalized mean parameter shows that it almost does not depend on data. The optimal power always occurs to be close to 1.7, …

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A Comparison Of Two Rank Tests For Repeated Measure Designs, Tian Tian, Rand R. Wilcox May 2007

A Comparison Of Two Rank Tests For Repeated Measure Designs, Tian Tian, Rand R. Wilcox

Journal of Modern Applied Statistical Methods

This article compares the small-sample properties of the Agresti-Pendergast and the ATS rank-based method, as described in Brunner, Domh, and Langer (2002), for comparing J dependent groups. The results indicate that the Type I error of the Agresti-Pendergast method is more conservative when J = 2 , but under most conditions, the ATS method performs best in terms of both Type I errors and power.

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Jmasm27: An Algorithm For Implementing Gibbs Sampling For 2pno Irt Models (Fortran), Yanyan Sheng, Todd C. Headrick May 2007

Jmasm27: An Algorithm For Implementing Gibbs Sampling For 2pno Irt Models (Fortran), Yanyan Sheng, Todd C. Headrick

Journal of Modern Applied Statistical Methods

A Fortran 77 subroutine is provided for implementing the Gibbs sampling procedure to a normal ogive IRT model for binary item response data with the choice of uniform and normal prior distributions for item parameters. The subroutine requires the user to have access to the IMSL library. The source code is available at http://www.siu.edu/~epse1/sheng/Fortran/, along with a stand alone executable file.

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Mathmatics In Volume I Of Scripta Universitatis, Shlomo S. Sawilowsky May 2007

Mathmatics In Volume I Of Scripta Universitatis, Shlomo S. Sawilowsky

Journal of Modern Applied Statistical Methods

Immanuel Velikovsky’s journal, Scripta Universitatis, edited by Albert Einstein and first published in 1923, played a significant role in the establishment of the library, and hence, Hebrew University in Jerusalem. The inaugural issue contained an article by the French mathematician Jacques Hadamard. Excerpts from Velikovsky’s diary pertaining to the rationale for the creation of the journal, and the interest in Jewish scholars such as Hadamard, are translated here.

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Practical Unit-Root Analysis Using Information Criteria: Simulation Evidence, Kosei Fukuda May 2007

Practical Unit-Root Analysis Using Information Criteria: Simulation Evidence, Kosei Fukuda

Journal of Modern Applied Statistical Methods

The information-criterion-based model selection method for detecting a unit root is proposed. The simulation results suggest that the performances of the proposed method are usually comparable to and sometimes better than those of the conventional unit-root tests. The advantages of the proposed method in practical applications are also discussed.

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Tests For Treatment Group Equality When Data Are Nonnormal And Heteroscedastic, Robert A. Cribbie, Rand R. Wilcox, Carmen Bewell, H. J. Keselman May 2007

Tests For Treatment Group Equality When Data Are Nonnormal And Heteroscedastic, Robert A. Cribbie, Rand R. Wilcox, Carmen Bewell, H. J. Keselman

Journal of Modern Applied Statistical Methods

Several tests for group mean equality have been suggested for analyzing nonnormal and heteroscedastic data. A Monte Carlo study compared the Welch tests on ranked data and heterogeneous, nonparametric statistics with previously recommended procedures. Type I error rates for the Welch tests on ranks and the heterogeneous, nonparametric statistics were well controlled with a slight power advantage for the Welch tests on ranks.

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A Fano-Huffman Based Statistical Coding Method, Aladdin Shamilov, Senay Asma May 2007

A Fano-Huffman Based Statistical Coding Method, Aladdin Shamilov, Senay Asma

Journal of Modern Applied Statistical Methods

Statistical coding techniques have been used for lossless statistical data compression, applying methods such as Ordinary, Shannon, Fano, Enhanced Fano, Huffman and Shannon-Fano-Elias coding methods. A new and improved coding method is presented, the Fano-Huffman Based Statistical Coding Method. It holds the advantages of both the Fano and Huffman coding methods. It is more easily applicable than the Huffman coding methods and it is more optimal than Fano coding method. The optimality with respect to the other methods is realized on the basis of English, German, Turkish, French, Russian and Spanish.

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Modeling Longitudinal Ordinal Response Variables For Educational Data, Ann A. O'Connell, Heather Levitt Doucette May 2007

Modeling Longitudinal Ordinal Response Variables For Educational Data, Ann A. O'Connell, Heather Levitt Doucette

Journal of Modern Applied Statistical Methods

This article presents applications for the analysis of multilevel ordinal response data through the proportional odds model. Data are drawn from the public-use Early Childhood Longitudinal Study. Results showed that gender, number of family risk characteristics, and age at kindergarten entry were associated with initial reading proficiency (0 to 5 scale). The number of family risks and age were associated with time-slopes. Three issues are highlighted: building multilevel ordinal models, interpretation of multilevel effects; and determination of predicted probabilities based on results of the multilevel proportional odds models.

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