ABSTRACT
One of the most common applications of statistics in the behavioral and social sciences is the comparison of means obtained from different treatments, from different groups, or from different measurements. For example, there are thousands of studies published each year that involve comparisons between a treatment group that has received some sort of intervention or special treatment and a control group that has not received this intervention. Other comparisons might involve assessing differences between scores obtained prior to some treatment or intervention (pre-test) with scores obtained subsequent to that treatment (post-test). Still other comparisons might contrast the average scores across several groups that receive different treatments or combinations of treatments.
