A simplified guide to determination of sample size requirements for estimating the value of intraclass correlation coefficient: a review

ABSTRACT

Intraclass correlation coefficient (ICC) measures the extent of agreement and consistency among raters for two or more numerical or quantitative variables. This review paper aimed to present several tables that could illustrate the minimum sample sizes required for estimating the desired effect size of ICC, which is a measurement of the magnitude of an agreement. Determination of the minimum sample size under such circumstances is based on the two fundamentally important parameters, namely the actual value of the ICC and the number of observations made by each subject. The sample size calculations are derived from Power Analysis and Sample Size (PASS) software where the alpha and minimum required power is fixed at 0.05 and higher than 0.80 respectively. A discussion on how to use these tables for determining sample sizes required for each of the various scenarios and the limitations associated with their use in each of these scenarios is provided.