In which sampling method is the unit not an individual but larger naturally occurring groups?

Cluster sampling is a method where the research population is divided into larger, naturally occurring groups, known as clusters. Instead of sampling individual members of the population directly, researchers randomly select entire clusters to represent the population. This approach is particularly useful when the population is large or dispersed, as it can be more practical and cost-effective than attempting to sample individuals directly.

In contrast, random sampling involves selecting individuals from the population at random without regard to larger groupings. Stratified sampling, on the other hand, divides the population into subgroups based on specific characteristics and samples individuals from each subgroup, while systematic sampling uses a fixed interval to select individuals from a list. These other methods focus on individuals or specific demographic subdivisions rather than the larger, naturally occurring groups that define cluster sampling.