A region is divided into 50 villages for the purpose of a survey. 10 villages are then selected randomly for the purpose of a study. This type of sampling is termed as:: (A) Simple Random sampling, (B) Stratified sampling, (C) Cluster Sampling, (D) Systematic Sampling
Answer is C. Cluster samples may be chosen where individuals fall naturally into groups or clusters. In the above scenario, a sample of the clusters is chosen at random, and then a random sample of units is chosen from within this selection of clusters. The villages are naturally formed groups or clusters in the region. Ref: Encyclopaedic Companion to Medical Statistics, Editors Brian S. Everitt and Christopher R. Palmer, Second Edition; Oxford Handbook of Medical Statistics, By Janet L. Peacock, Philip J. Peacock, Oxford University Press 2011, Page 55.