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open access

The Generalization of the Logistic Discriminant Function Analysis and Mantel Score Test Procedures to Detection of Differential Testlet Functioning

Description: Two procedures for detection of differential item functioning (DIF) for polytomous items were generalized to detection of differential testlet functioning (DTLF). The methods compared were the logistic discriminant function analysis procedure for uniform and non-uniform DTLF (LDFA-U and LDFA-N), and the Mantel score test procedure. Further analysis included comparison of results of DTLF analysis using the Mantel procedure with DIF analysis of individual testlet items using the Mantel-Haenszel (… more
Date: August 1994
Creator: Kinard, Mary E.
Partner: UNT Libraries
open access

A Comparison of Three Criteria Employed in the Selection of Regression Models Using Simulated and Real Data

Description: Researchers who make predictions from educational data are interested in choosing the best regression model possible. Many criteria have been devised for choosing a full or restricted model, and also for selecting the best subset from an all-possible-subsets regression. The relative practical usefulness of three of the criteria used in selecting a regression model was compared in this study: (a) Mallows' C_p, (b) Amemiya's prediction criterion, and (c) Hagerty and Srinivasan's method involving … more
Date: December 1994
Creator: Graham, D. Scott
Partner: UNT Libraries
open access

A Comparison of Two Differential Item Functioning Detection Methods: Logistic Regression and an Analysis of Variance Approach Using Rasch Estimation

Description: Differential item functioning (DIF) detection rates were examined for the logistic regression and analysis of variance (ANOVA) DIF detection methods. The methods were applied to simulated data sets of varying test length (20, 40, and 60 items) and sample size (200, 400, and 600 examinees) for both equal and unequal underlying ability between groups as well as for both fixed and varying item discrimination parameters. Each test contained 5% uniform DIF items, 5% non-uniform DIF items, and 5% com… more
Date: August 1995
Creator: Whitmore, Marjorie Lee Threet
Partner: UNT Libraries
open access

An Empirical Comparison of Random Number Generators: Period, Structure, Correlation, Density, and Efficiency

Description: Random number generators (RNGs) are widely used in conducting Monte Carlo simulation studies, which are important in the field of statistics for comparing power, mean differences, or distribution shapes between statistical approaches. Statistical results, however, may differ when different random number generators are used. Often older methods have been blindly used with no understanding of their limitations. Many random functions supplied with computers today have been found to be comparativel… more
Date: August 1995
Creator: Bang, Jung Woong
Partner: UNT Libraries
open access

The Effect of Psychometric Parallelism among Predictors on the Efficiency of Equal Weights and Least Squares Weights in Multiple Regression

Description: There are several conditions for applying equal weights as an alternative to least squares weights. Psychometric parallelism, one of the conditions, has been suggested as a necessary and sufficient condition for equal-weights aggregation. The purpose of this study is to investigate the effect of psychometric parallelism among predictors on the efficiency of equal weights and least squares weights. Target correlation matrices with 10,000 cases were simulated so that the matrices had varying degr… more
Date: May 1996
Creator: Zhang, Desheng
Partner: UNT Libraries
open access

Measurement Disturbance Effects on Rasch Fit Statistics and the Logit Residual Index

Description: The effects of random guessing as a measurement disturbance on Rasch fit statistics (unweighted total, weighted total, and unweighted ability between) and the Logit Residual Index (LRI) were examined through simulated data sets of varying sample sizes, test lengths, and distribution types. Three test lengths (25, 50, and 100), three sample sizes (25, 50, and 100), two item difficulty distributions (normal and uniform), and three levels of guessing (no guessing (0%), 25%, and 50%) were used in t… more
Date: August 1997
Creator: Mount, Robert E. (Robert Earl)
Partner: UNT Libraries
open access

Ability Estimation Under Different Item Parameterization and Scoring Models

Description: A Monte Carlo simulation study investigated the effect of scoring format, item parameterization, threshold configuration, and prior ability distribution on the accuracy of ability estimation given various IRT models. Item response data on 30 items from 1,000 examinees was simulated using known item parameters and ability estimates. The item response data sets were submitted to seven dichotomous or polytomous IRT models with different item parameterization to estimate examinee ability. The accur… more
Date: May 2002
Creator: Si, Ching-Fung B.
Partner: UNT Libraries
open access

Establishing the utility of a classroom effectiveness index as a teacher accountability system.

Description: How to identify effective teachers who improve student achievement despite diverse student populations and school contexts is an ongoing discussion in public education. The need to show communities and parents how well teachers and schools improve student learning has led districts and states to seek a fair, equitable and valid measure of student growth using student achievement. This study investigated a two stage hierarchical model for estimating teacher effect on student achievement. This me… more
Date: May 2002
Creator: Bembry, Karen L.
Partner: UNT Libraries
open access

A comparison of traditional and IRT factor analysis.

Description: This study investigated the item parameter recovery of two methods of factor analysis. The methods researched were a traditional factor analysis of tetrachoric correlation coefficients and an IRT approach to factor analysis which utilizes marginal maximum likelihood estimation using an EM algorithm (MMLE-EM). Dichotomous item response data was generated under the 2-parameter normal ogive model (2PNOM) using PARDSIM software. Examinee abilities were sampled from both the standard normal and unif… more
Date: December 2004
Creator: Kay, Cheryl Ann
Partner: UNT Libraries
open access

Bias and Precision of the Squared Canonical Correlation Coefficient under Nonnormal Data Conditions

Description: This dissertation: (a) investigated the degree to which the squared canonical correlation coefficient is biased in multivariate nonnormal distributions and (b) identified formulae that adjust the squared canonical correlation coefficient (Rc2) such that it most closely approximates the true population effect under normal and nonnormal data conditions. Five conditions were manipulated in a fully-crossed design to determine the degree of bias associated with Rc2: distribution shape, variable sets… more
Date: August 2006
Creator: Leach, Lesley Ann Freeny
Partner: UNT Libraries
open access

The Supply and Demand of Physician Assistants in the United States: A Trend Analysis

Description: The supply of non-physician clinicians (NPCs), such as physician assistant (PAs), could significantly influence demand requirements in medical workforce projections. This study predicts supply of and demand for PAs from 2006 to 2020. The PA supply model utilized the number of certified PAs, the educational capacity (at 10% and 25% expansion) with assumed attrition rates, and retirement assumptions. Gross domestic product (GDP) chained in 2000 dollar and US population were utilized in a transfer… more
Date: May 2007
Creator: Orcutt, Venetia L.
Partner: UNT Libraries
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