Cluster Sampling and Area Sampling: Cluster sampling involves grouping the population and then selecting the group or the cluster rather than individual elements for inclusion in the sample. The clustering approach can however make the sampling procedure relatively easier and increase the efficiency of fieldwork especially in the case of personal interviews,

Area sampling is generally done when the total geographical area of interest is big one. We first divide the total area into a number of smaller non over lapping areas generally called geographical clusters then a number of these smaller areas are randomly selected and all units in the small areas are included in the sample.