Determining the Sample for Medical Research by Plotting Power as a Function of Effect Size and Sample Size

The objective of this study is to develop an optimal sample size for use in medical research studies by plotting power as a function of effect size and sample size. The paper is designed as a tool that a researcher can use in planning and conducting good quality research and gives a discussion of various aspects of sample size consideration in medical research. The paper also covers the essentials of calculating power and sample size for a variety of applied study designs. Sample size computation for survey type of studies, observation studies, and experimental studies based on means and proportions or rates, sensitivity–specificity tests for assessing the categorical outcome are presented in detail. Recently, considerable interest has been focused on medical research after the beginning of the COVID-19 pandemic. The resulting literature is scattered over many sources. This paper aims to give some contributions in this field.