Editing Cluster sampling (section)

==Advantages==

* Can be cheaper than other sampling plans – e.g. fewer travel expenses, and administration cost.
*Feasibility: This sampling plan takes large populations into account. Since these groups are so small, deploying any other sampling plan would be very costly.
*Economy: The regular two major concerns of expenditure, i.e., traveling and listing, are greatly reduced in this method. For example: Compiling research information about every household in a city would be very costly, whereas compiling information about various blocks of the city will be more economical. Here, traveling as well as listing efforts will be greatly reduced.
*Reduced variability: in the rare case of a negative [[intraclass correlation]] between subjects within a cluster, the estimators produced by cluster sampling will yield more accurate estimates than data obtained from a [[simple random sample]] (i.e. the [[design effect]] will be larger than 1). This is not a commonplace scenario. 
Major use: when the sampling frame of all elements is not available we can resort only to cluster sampling.