A primary objective of many studies is to demonstrate a difference between two or more treatments under investigation. Power analysis, also referred to as sample size calculation, plays an important role in ensuring that a sufficient number of subjects are enrolled for answering the question of interest. Specifically, it is important to design a study in such a way that it will have a high probability of showing a difference when a difference truly exists and a low probability of showing a difference when none exists. If the sample size is too small, the study will be underpowered and may lead to discarding a potentially useful treatment. Such underpowered studies often lead to great confusion in the literature because they are often perceived as negative ...