This study of maximum likelihood confirmatory factor analysis found effects of practical significance due to sample size, the number of indicators per factor, and the number of factors for Joreskog and Sorbom's (1981) goodness-of-fit index (GFI), GFI adjusted for degrees of freedom, and the root mean square residual. (Author/BW)

An electronic survey of a listserv discussion group, the Interdisciplinary Teamed Instruction (ITI) group, was conducted to learn more about the group and to explore surveying electronically. A 10-question survey was posted electronically, as were respondents' replies. Three reminders were posted over the 3-week reply period. The number of…

A methodology for estimating descriptive statistics, specifically the mean and the variance, from a sample that is not normally drawn is described. The method involves breaking the sample down into subgroups and weighting the descriptive statistics associated with each subgroup by the proportion of the population that the subgroup represents. This…

Investigates the role of causal mechanism, sampling method, and sample size in causal reasoning of 216 sixth and ninth grade and college students. Subjects did not base judgments solely on covariation. Age differences were negligible when covariation was absent and striking when covariation was present. (RJC)

Type I error rate and power for the t test, Wilcoxon-Mann-Whitney test, van der Waerden Normal Scores, and Welch-Aspin-Satterthwaite (W) test are compared for two simulated independent random samples from nonnormal distributions. Conditions under which the t test and W test are best to use are discussed. (SLD)

Application of the bootstrap method to complex psychological analysis is illustrated using a simulation experiment with two populations with small and large samples. The method provides variance estimates, allows testing of nested competing models, and gives a preliminary idea about parameter variability. (SLD)

A method is proposed for calculating the sample size needed to achieve acceptable statistical power with a given test. The minimally important difference significant (MIDS) criterion for sample size is explained and supported with recommendations for determining sample size. The MIDS criterion is computationally simple and easy to explain. (SLD)

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 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 feasibility of quick norms derived by the procedure described by B. D. Wright and M. H. Stone (1979) was investigated. Norming differences between traditionally calculated means and Rasch "quick" means were examined for simulated data sets of varying sample size, test length, and type of distribution. A 5 by 5 by 2 design with a…

Possible bias due to sampling problems or low response rates has been a troubling "nuisance" variable in empirical research since seminal and classical studies were done on these problems at the beginning of this century. Recent research suggests that: (1) earlier views of the alleged bias problem were misleading; (2) under a variety of fairly…

Parametric analysis of covariance was compared to analysis of covariance with data transformed using ranks. Using a computer simulation approach the two strategies were compared in terms of the proportion of Type I errors made and statistical power when the conditional distribution of errors were: (1) normal and homoscedastic, (2) normal and…

The accuracy and variability of 4 cross-validation procedures and 18 formulas were compared concerning their ability to estimate the population multiple correlation and the validity of the sample regression equation in the population. The investigation included two types of regression, multiple and stepwise; three sample sizes, N = 30, 60, 120;…

Three related studies were conducted to examine the effects of variations in procedures used for curriculum-based assessment of reading proficiency: the first addressed the question of the influence of sample duration on the concurrent validity of the measure; the second addressed the question of the influence of sample duration on the level,…

Arguments have recently been put forth that standard textbook procedures for determining the sample size necessary to achieve a certain level of power in a completely randomized design are incorrect when the dependent variable is fallible because they ignore measurement error. In fact, however, there are several correct procedures, one of which is…