Concepts and Definitions

What is a population?

A population is a group of individuals or units (e.g. households, companies) that one would like to understand. Specifically, we call this group the target population. Let’s look at an example.

The example introduced two types of surveys; a census and a sample survey.

What is a census?

A census is a survey that collects data from all persons or units in the target population.

What is a sample?

A sample is a subset of the target population from which data are collected. For each population, there are many possible samples. Careful steps are taken in selecting this sample to ensure that it is representative of the target population, so that the findings from the sample survey can be extended to the target population.

The sample survey is a common method used to collect information on the population of interest, usually due to resource constraints.