In a sample survey , a sample of units drawn from the population of interest is analyzed. A related concept is the census survey .

The main advantage of the sample survey (as compared to the census survey ) is that its implementation is technically simpler - because data are collected on only a fraction of the population (often a tiny fraction). The shortcoming is that the sampling procedure may introduce random errors and systematic errors .

See also: random sampling and the short online course Survey Design and Sampling Procedures