The term “statistical power” is a shorthand for “the power of a statistical test to detect a change in Y” but many books only use the phrase “statistical power” without any explanation/expansion of the term. Only using the phrase “statistical power” makes learning the topic more difficult. Calculation of “the power of a test to detect a change in Y” is tremendously important in research effectiveness and is directly tied to the cost of doing research. The topic is considered to be difficult and learning how to handle the many types of statistical power calculations is, to some extent, requires an overview of all of the statistics courses you’ve ever taken. SAS has done much to make the calculation of statistical power fast and easy.