ABSTRACT
Analysis of covariance (ANCOVA) is a most useful technique for exploring differences among treatment groups when the DV is influenced not just by our treatments but also by at least one other variable that we can measure but may not be able to control. It combines the ANOVA technique to examine the effect of different levels of a treatment factor with the regression technique to allow for the effect of a random nuisance variable, called a covariate, on the outcome. Once the variables are entered we need to click the Model button to specify the model to be used, and again we get the same one as we used in ANOVA.
