THE WHAT, WHY AND HOW OF SAMPLE SIZE ESTIMATION IN CLINICAL TRIALS

The choice of adequate number of subjects that would ensure accurate estimates is an important one in a clinical trial setting. Although complexity of a formula increases with complexity in study design, the basic structure of a sample size calculation formula is very simple. This paper attempts to review the basic requirements for computation of the magic number required to estimate unknown target population quantities and to test treatment differences for continuous as well as binary outcomes. Concepts are demonstrated through simple examples. Using online calculators for sample size is also discussed.