ABSTRACT
Sample size calculations are a vital part of the design of a clinical trial. A sample size calculation ensures that a study remains ethical by not treating more patients than absolutely necessary to answer a pre-defined study question, whilst ensuring there are enough patients enrolled to reach a conclusion.
In this chapter, the theory behind the sample size calculations is presented along with worked examples for calculating sample sizes for superiority, equivalence and non-inferiority trial designs. The examples are presented for both continuous and binary endpoints, along with some examples of using standard “quick results” methods. Tables of various sample size conditions are also presented for reference and can be used to estimate sample sizes for certain study designs.
