Simulations demonstrate the effects of correlated errors on the person-by-occasion design in which the confounding effect of equal time intervals results in correlated error terms in the linear model. Two specific error correlation structures were examined. Conditions under which underestimation and overestimation occur are discussed. (SLD)

Generalizability theory is based upon analysis of variance (ANOVA) and requires estimation of variance components for the ANOVA design under consideration in order to compute either G (Generalizability) or D (Decision) coefficients. Estimation of variance components has a number of alternative methods available using SAS, BMDP, and ad hoc…

This study is an attempt at a cohesive characterization of the concept of essay reliability. As such, it takes as a basic premise that previous and current practices in reporting reliability estimates for essay tests have certain shortcomings. The study provides an analysis of these shortcomings--partly to encourage a fuller understanding of the…

There is a natural tension between experimentally designed studies and case studies, which differ in that they are not concerned with the interaction of variables in the quantitative and statistical sense. This paper describes a study that was not experimentally designed, but its major findings were generalizable to the overall population of…

Statistical significance is misused in educational and psychological research when it is applied as a method to establish the reliability of research results. Other techniques have been developed which can be correctly utilized to establish the generalizability of findings. Methods that do provide such estimates are known as invariance or…