ABSTRACT

This chapter discusses one-stage cluster sampling, in which every element within a sampled cluster is included in the sample. It describes design issues for cluster sampling, including selection of subsample and sample sizes. The chapter deals with theory of cluster sampling from the model-based perspective. In simple random sampling, the units sampled are also the elements observed. In cluster sampling, the sampling units are the clusters and the elements observed are the secondary sampling units (ssus) within the clusters. In one-stage cluster sampling, either all or none of the elements that compose a cluster are in the sample. One-stage cluster sampling is used in many surveys in which the cost of sampling ssus is negligible compared with the cost of sampling primary sampling units. If the clusters occur naturally in the population, the Intra class correlation coefficient is usually positive. Elements within the same cluster tend to be more similar than elements selected at random from the population.