All differential item functioning (DIF) methods require at least a moderate sample size for effective DIF detection. Samples that are less than 200 pose a challenge for DIF analysis. Smoothing can improve upon the estimation of the population distribution by preserving major features of an observed frequency distribution while eliminating the…

This article examines theoretical and empirical issues related to the statistical power of impact estimates for experimental evaluations of education programs. The author considers designs where random assignment is conducted at the school, classroom, or student level, and employs a unified analytic framework using statistical methods from the…

This article familiarizes readers with how to analyze personnel selection decisions in employment discrimination litigation. First, the authors outline some of the basic legal principles that serve as the basis for analyses related to claims of discriminatory employment practices. Second, they describe how to conduct a scientific investigation of…

Multiple matrix sampling is a sampling design in which both test items and examinees are randomly sampled from their respective populations. This study was designed to develop and assess a method for computing an estimate of a correlation coefficient when a multiple matrix sampling design is used. The examinee populations included 212 third-grade…

Considered the statistical comparison of groups under the condition of equal sample sizes. (Author)

A sampling theorem, based on the binomial probability distribution but otherwise distribution-free, is derived and some of its applications are illustrated numerically. (Author)

Problems of sampling error and accumulated rounding error in canonical variate analysis are discussed. A new technique is presented which appears to be superior to canonical variate analysis when the ratio of variables to sampling units is greater than one to ten. Examples are presented. (Author/JKS)

Bootstrap methodology is presented that yields approximations of the sampling variation of redundancy estimates while assuming little a priori knowledge about the distributions of these statistics. Results of numerical demonstrations suggest that bootstrap confidence intervals may offer substantial assistance in interpreting the results of…

Randomized controlled trials in educational research tend to be small. Small trials can have large, chance, imbalances in important covariates. For studies with sample sizes greater than 50, chance imbalances can be corrected using analysis of covariance; for small trials, however, statistical power is maximized if the trial is balanced and…

The purpose of this study was to examine the correlation between online survey non-response and various demographic factors, including gender. Studies have shown that trends exist with regard to who responds to surveys, at least with regard to traditional modes of survey administration. Reports suggest that many demographic and other correlates…