1.7 (Optional) Cluster sampling
In cluster sampling, the population is split into a large number of small groups called clusters, then a simple random sample of clusters is selected and every member of the chosen small groups is part of the sample.
Example 1.7 (Cluster sampling) To select students in a large course at a particular university again, a simple random sample of (say) three of the many tutorials could be selected, and every student enrolled in those selected tutorials constitute the sample.
The animation below shows how a sample of approximately 40 students could be obtained using cluster sampling, using the tutorials as clusters.