REGRESSION-ANALYSIS WITH CLUSTERED DATA

Clustered data are found in many different types of studies, for examp le, studies involving repeated measures, inter-rater agreement studies , household surveys, crossover designs and community randomized trials . Analyses based on population average and cluster specific models are commonly used for estimating treatment (exposure) effects with cluste red data. This paper discusses conditions when one or both types of mo dels are appropriate for estimating causal effects and when there is a greement between population average and cluster specific analyses. App lications of survey sampling methods to the robust estimation of stand ard errors of estimated treatment parameters are discussed.