Effect Size and Power of a Test in Sample Size Determination for Clinical Research

Abstract

Effect size and power of a test are used in sample size determination and in clinical research which the sample size is smaller than the survey research. The sample size calculators are available online i.e.; G*Power, Power and Sample Size .com Calculators, and Sample Size Calculators.  The input parameters to these programs are the type of test statistics, number of population, significance level (confidence interval 1- ), type II error ( ) or power of a test (1- ), and effect size ( ), these are very important tools for researchers.  This article presented terms and definitions and derived the sample size formula for researchers to appropriate use of those sample size calculation programs.