A multi-stage sample is one in which sampling is done sequentially across two or more hierarchical levels, such as first at the county level, second at the census track level, third at the block level, fourth at the household level, and ultimately at the within-household level.

Many probability sampling methods can be classified as single-stage sampling versus multi-stage sampling. Single-stage samples include simple random sampling, systematic random sampling, and stratified random sampling. In single-stage samples, the elements in the target population are assembled into a sampling frame; one of these techniques is used to directly select a sample of elements. In contrast, in multi-stage sampling, the sample is selected in stages, often taking into account the hierarchical (nested) structure of the population. The target population of ...