The present authors argued that the covariance analysis is completely valid even if there is a true main effect for pretesting and a second point of the paper involved a recommendation for data analysis if the interaction from ANOVA was significant. (Editor/RK)

Action research often necessitates the use of intact groups for the comparison of educational treatments or programs. This paper considers several analytical methods that might be used for such situations when pretest scores indicate that these intact groups differ significantly initially. The methods considered include gain score analysis of…

The measurement of change is such a broad topic that this article must limit its focus to a few specific subtopics. These specific topics include: longitudinal research design, attrition in research studies, the statistical analysis of difference scores, and the comparison of analysis of variance (ANOVA) and multivariate analysis of variance…

When two groups, initially dissimilar, undergo different treatments, can subsequent differences be partitioned in such a way that the difference between the two treatments is unbiased? This is the central problem of this paper, and it is confronted by the examination of two levels of information using a Follow Through Evaluation. The first…