Sample Size Calculation Guide - Part 1: How to Calculate the Sample Size Based on the Prevalence Rate

Sample size calculation is an essential methodological issue in clinical research. It is crucial to ensure that the study has sufficient participants in order to detect the expected effect estimate. Moreover, it has been advocated that the underpowered clinical trials lead to wastage of time, money, and resources, and are not ethical as they do not generate expected results and expose the patients to a higher risk. Considering the importance of this methodological point, we shall commence the research methodology section of the Advanced Journal of Emergency Medicine with a series of educational letters explaining the method to calculate the sample size for various clinical research study designs. For more illustration, each educational note will be accompanied by a real-life example from the published articles in emergency medicine research. This is the first article of our educational series where we have explained the sample size calculation based on a prevalence rate.