which of these approaches is generally done in a multi-stage sample? a.) the total population is divided into groups and then some groups are randomly selected. b.) a sample is made by randomly picking out elements from the total population. c.) a sample is made by randomly picking every nth element of the total population. d.) the population is subdivided into smaller and smaller clusters which are then sampled.

Multistage sampling is the process of taking samples in stages, with successively smaller sampling units. Given that multistage sampling requires segmenting the population into groups, it can be a complex variation on cluster sampling.

The population is first segmented into clusters, and some of them are chosen as primary sample units (PSUs).

In the subsequent stage, we further cluster PSUs and choose some of them to serve as secondary sampling units (SSUs).

The process can be stopped at stage two or extended as many times as necessary. The final sample is the ultimate sampling units (USUs).

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