Sample Size Calculation for Dichotomous Outcomes in Cluster Randomization Trials with Varying Cluster Size

It is common to assume a constant cluster size in the estimation of sample size for cluster randomized trials. Manatunga et al. (1) derived sample size estimation for continuous response variables in cases of varying cluster size. This paper discusses a parallel study for binary response variables. We compare the maximum cluster size method, the average cluster size method, and the proposed method.