Required sample size for comparing means in two paired samples

Abstract

This paper continues our series of articles for beginners on required sample size for the most common basic statistical tests used in biomedical research. The most common statistical test for comparing means in paired samples is Student’s paired t-test. In this paper we present a simple algorithm for calculating required sample size for comparing two means in paired samples. As in our earlier papers we demonstrate how to perform calculations using WinPepi and Stata software. Moreover, we have created a table with calculated minimal sample sizes required for using Student’s t-tests for different scenarios with the confidence level of 95% and statistical power of 80%.