We investigate the impact of cluster sampling on standard errors in the analysis of longitudinal survey data. We consider a widely used class of regression models for longitudinal data and a standard class of point estimators of a generalized least squares type. We argue theoretically that the...

The design effect measures the inflation of the sampling variance of an estimator as a result of the use of a complex sampling scheme. It is usually measured relative to the variance of the estimator under simple random sampling. Many social survey designs employ multi-stage sampling, leading to...