ABSTRACT
Some authors choose to refer to the topic of sample size calculation as sample size estimation. This word choice is understandable because the calculation of the sample size for a clinical trial is based on design parameters whose values are estimated from previous data, or some other form of external information or assumptions. On the other hand, some authors prefer to use the term calculation for sample size to distinguish from the estimation of a model parameter in the context of making statistical inferences; these estimated values are usually assumed as fixed in the calculation, and seldom considered for their uncertainty. We use calculation and estimation interchangeably in this book.
