Cluster sampling intact groups – UGC NET Question

Cluster sampling selects naturally occurring groups, or clusters, such as classrooms, villages or city blocks, rather than individual elements at the first stage. After clusters are randomly chosen, all or a sample of elements within each cluster are studied. This method is particularly useful when a complete list of individuals is unavailable but a list of clusters exists. Thus, the technique described in the stem is correctly called cluster sampling.

Option A:
Systematic sampling chooses every kth element from an ordered list after a random start and does not focus on intact groups such as villages. Its selection pattern is interval-based, not cluster-based. So it is not the right option.

Option B:
Stratified sampling divides the population into homogeneous strata and draws random samples from each stratum. It ensures representation of each subgroup but does not necessarily treat intact groups as primary units. Therefore, it does not match the stem.

Option C:
Quota sampling is a non-probability method in which the researcher fills predetermined numbers in specific categories using convenience selection. It is not a cluster-based probability technique. Hence, it cannot complete the blank.

Option D:
Option D, cluster, explicitly involves random selection of group units followed by study of members within those units. This is exactly the approach described in the question, making this option correct.