Background: Several studies showed a different symptom structure underlying the spectrum of autistic-like disorders from the behaviour triad as mentioned in the DSM-IV. In the present study, a hypothesised symptom model for autism was constructed, based on earlier explorative findings, and was put to a confirmatory test. Method: Items from the…

Intraclass correlation and Cronbach's alpha are widely used to describe reliability of tests and measurements. Even with Gaussian data, exact distributions are known only for compound symmetric covariance (equal variances and equal correlations). Recently, large sample Gaussian approximations were derived for the distribution functions. New exact…

A simulation study was conducted to examine the effect of item parceling on confirmatory factor analysis parameter estimates and their standard errors at different levels of sample size, number of indicators per factor, size of factor structure/pattern coefficients, magnitude of interfactor correlations, and variations in item-level data…

We discuss the challenges of small-subsample sizes that family scholars often encounter when studying nontraditional or less common family types. We begin by identifying the general difficulties of using existing data in this line of research and then discuss potential solutions that may help researchers to avoid these problems. Using data from…

Purpose: The purpose of this study was to develop guidelines for the statistical analysis of percentage of syllables stuttered (%SS) data in stuttering research. Method; Data on %SS from various independent sources were used to develop a statistical model to describe this type of data. On the basis of this model, %SS data were simulated with…

Differential item functioning (DIF) continues to receive attention both in applied and methodological studies. Because DIF can be an indicator of irrelevant variance that can influence test scores, continuing to evaluate and improve the accuracy of detection methods is an essential step in gathering score validity evidence. Methods for detecting…

Learning communities are a popular strategy that community colleges nationwide have embraced in support of developmental students. In a learning community, a cohort of students takes two or more courses linked by integrated themes and assignments that are developed through ongoing faculty collaboration. While the number of learning community…

Discriminant analysis (DA) is a multivariate technique concerned with either prediction/classification (predictive discriminant analysis) or distinguishing among groups (descriptive discriminant analysis). DA has many potential applications in gifted education research, including investigation of identification procedures in order to obtain…

This paper describes a study, now in progress, of new methods for representing the sampling variability of Mantel-Haenszel differential item functioning (DIF) results, based on the system for categorizing the severity of DIF that is now in place at the Educational Testing Service. The methods, which involve a Bayesian elaboration of procedures…

This study extended item parameter recovery studies in item response theory to the nominal response model (NRM). The NRM may be used with computerized adaptive testing, testlets, demographic items, and items whose alternatives provide educational diagnostic information. Moreover, with the increasing popularity of performance-based assessment, the…

This document provides a summary and evaluation of the methodological procedures and results of the full-scale implementation of the Beginning Postsecondary Student Longitudinal Study Second Follow-up, 1990-94 (BPS:90/94). The study was conducted for the National Center for Education Statistics by Research Triangle Institute with the assistance of…

The stability of bias estimates from J. Schueneman's chi-square method, the transformed Delta method, Rasch's one-parameter residual analysis, and the Mantel-Haenszel procedure, were compared across small and large samples for a data set of 30,000 cases. Bias values for 30 samples were estimated for each method, and means and variances of item…

The use of two alternative item response theory (IRT) estimation models in the scaling and equating of the Test of English as a Foreign Language (TOEFL) was explored; and item scaling and test equating results based on these models were compared with results based on the three-parameter (3PL) model currently being used with the TOEFL. Models were…

Type I error rates of the likelihood ratio test for the detection of differential item functioning (DIF) were investigated using Monte Carlo simulations. The graded response model with five ordered categories was used to generate data sets of a 30-item test for samples of 300 and 1,000 simulated examinees. All DIF comparisons were simulated by…

The effect of interview length on wave nonresponse in a longitudinal survey was studied, controlling for respondent-specific characteristics known to affect survey response. Data from the National Longitudinal Survey of Youth were used, for a sample of over 10,000 people who were 14 to 22 years old when first interviewed in 1979. These individuals…