Question

What is the difference between a stratified random sample and a cluster random sample?

Answer 1

The main difference is that in stratified sampling, you select some units from EACH subgroup (called "strata"). In cluster sampling, you only select a certain number of subgroups (called "clusters"), but you select all the units from each cluster. But this is really more specifically called single-stage cluster sampling. You can have something called two-stage cluster sampling, in which you select SOME units from the clusters you got in single stage sampling. Let me illustrate this:

Answer 2

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