The authors empirically examined whether the validity of a residualized dependent variable after covariance adjustment is comparable to that of the original variable of interest. When variance of a dependent variable is removed as a result of one or more covariates, the residual variance may not reflect the same meaning. Using the pretest-posttest…

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)