GENERAL OVERVIEW OF SAMPLE SIZE ESTIMATION FOR RANDOMIZED CONTROLLED CLINICAL TRIALS

Abstract

Calculation of the minimum sample size needed to meet the primary study objective is a key feature of the design of any clinical trial. The other reason a priori sample size determination is to limit participant harm or loss of clinical benefit to as few study participants as possible. This article generally reviews the basic principles that determine an appropriate sample size and provides methods for its calculation in some simple, yet common, cases. Sample size is closely tied to statistical power, which is the ability of a study to enable detection of a statistically significant difference when there truly is one. A trade-off exists between a feasible sample size and adequate statistical power