ABSTRACT
This chapter deals with the problem of comparing two dependent groups. The most common method for comparing two dependent groups is based on what is called the paired T test. If independent groups having equal sample sizes are compared using the paired T test, power will be lower compared to using Student's T. However, if the correlation between the observations is sufficiently high, the paired T test will have more power. That is, given a choice when designing an experiment, comparing dependent groups is preferable to comparing independent groups. Testing the hypothesis that Pearson's correlation is equal to 0, using Student's T, can be unsatisfactory when variables are dependent, which means that the Morgan-Pitman test can be unsatisfactory when distributions differ. As for comparing dependent groups using a robust measure of scale, a basic percentile boot-strap method can be used.
