Final answer:
In a cluster sample, the population is divided into mutually exclusive groups (clusters) and the researcher draws a sample of the groups to interview. Cluster sampling is useful when it is easier and more cost-effective to sample clusters rather than individuals.
Step-by-step explanation:
In a cluster sample, the population is divided into mutually exclusive groups (clusters) and the researcher draws a sample of the groups to interview. For example, if a researcher wants to survey students in different schools, they might divide the population into clusters of schools and randomly select some of the schools to survey.
The students in the selected schools would then be interviewed. Cluster sampling is useful when it is easier and more cost-effective to sample clusters rather than individuals.