The term mean comparisons refers to the comparison of the average of one or more continuous variables over one or more categorical variables. It is a general term that can refer to a large number of different research questions and study designs. For example, one can compare the mean from one sample of data to a hypothetical population value, compare the means on a single variable from multiple independent groups, or compare the means for a single variable for one sample over multiple measurement occasions. In addition, more complex research designs can employ multiple continuous dependent variables simultaneously, as well as a combination of multiple groups and multiple measurement occasions. Overall, mean comparisons are of central interest in any experimental design and many correlational designs ...