A sample survey can be broadly defined as an exercise that involves collecting standardised data from a sample of study units (e.g., persons, households, businesses) designed to represent a larger population of units, in order to make quantitative inferences about the population. Within this broad definition there is a large variety of different types of survey. Surveys can differ in terms of the type of data collected, the methods used to collect the data, the design of the sample, and whether data is collected repeatedly, either on the same sample or on different samples. Key features of a sample survey are:
