Use of "special" orthonormal mean contrasts and mean contrast variances can help educational researchers interpret a wide variety of repeated measures data. Most statistical packages allow educational researchers to test for differences across repeated measures using both the univariate mixed model F test and a multivariate test.…

Each of the four classic multivariate analysis of variance (MANOVA) tests of statistical significance may lead a researcher to different decisions as to whether a null hypothesis should be rejected: (1) Wilks' lambda; (2) Lawley-Hotelling trace criterion; (3) Roy's greatest characteristic root criterion; and (4) Pillai's trace criterion. These…

In the educational research literature alpha, the a priori level of significance, and p, the a posteriori probability of obtaining a test statistic of at least a certain value when the null hypothesis is true, are often confused. Explanations for this confusion are offered. Paradoxically, alpha retains a prominent place in textbook discussions of…

A growing controversy surrounds the strict interpretation of statistical significance tests in social research. Statistical significance tests fail in particular to provide estimates for the stability of research results. Methods that do provide such estimates are known as invariance or cross-validation procedures. Invariance analysis is largely…

Statistical measures of practical significance report the extent to which variation in the dependent variable can be explained by the independent variable. Reports of special education research sometimes discuss practicality using the estimate of statistical significance. Practical significance, however, may vary greatly among samples even though…

Hypothetical data sets are used to demonstrate how canonical correlation methods subsume other commonly utilized parametric methods. Analysis of variance, analysis of covariance, multiple analysis of variance, and multiple analysis of covariance are heavily used by educational researchers. It is concluded that researchers would do well to consider…

Efforts to study the fidelity of translation of attitudinal scales into foreign languages have faltered due to the lack of powerful statistical tests to assess such transformations. This study uses a maximum likelihood factor analysis procedure to compare multivariate factor structures across subpopulations. The results showed that inconsistent…

This paper reports the results of a Monte Carlo investigation of Type I errors in the single group repeated measures design where multiple measures are collected from each observational unit at each measurement occasion. The Type I error of three multivariate tests were examined. These were the doubly multivariate F test, the multivariate mixed…

One limitation of hired farm labor data from the Decennial Census is undercounting; the seasonal nature of farm work means that many farm laborers are not employed in March, when the Census is taken. The 1981 Hired Farm Working Force Survey provided data to evaluate the usefulness of Census data for farm labor research. Data were grouped into…