Effective Sample Size

Complex sample surveys rarely result in a set of independent and identically distributed observations, because of sample design features such as stratification, clustering, and unequal weighting that are necessary for efficient data collection. Such features affect the resulting variance of survey estimates. The effective sample size is one of several useful measures of the effect of the complex sample design on the resulting precision of the estimates.

A general definition of the effective sample size is the sample size for a simple random sample selected with replacement that yields the same variance for an estimate as the variance obtained from the sample design used to collect the data. A simple random sample selected with replacement yields a set of independent observations and is the simplest comparison ...