To distinguish between stratified sampling and cluster sampling, using the following definitions:
Stratified - categories, to provide some sense of population within a population; key a predetermined strata, random within the strata.
Cluster - a population is divided into sectors (groups, clusters). Then random clusters are sampled. The entire population within a specific cluster is sampled; key predetermined cluster, all within the cluster.
What is the difference between stratified sampling and cluster sampling: is it that one is random within the strata and the other is all within a predetermined cluster?