Optimal sample sizes for two-stage cluster samplin in demographic and health surveys

Determining optimal sample size is a critical step in a DHS survey because it requires a trade-off between the budget available and the desired survey precision. This paper investigates the optimal sample sizes in different situations in DHS surveys, based on experiences of actual surveys. The results show that for an average cluster size of 100-300 households, for moderate intracluster correlation and cost ratio, the optimal second-stage sample size is about 20 women per cluster. The results also show that for most of the DHS surveys the sample sizes met the optimal standard or were within tolerable limits of relative precision loss. (Author abstract)