A census is a study of every unit in a population. It is a “complete enumeration“, which means a complete count.

A sample is a subset of units in a population. It is a “partial enumeration” because it is a count of part of the population.

A census is a complete count of a population and provides a true measure of the population.

By contrast, a sample is a subset of units of a population. A sample is used to make inferences about the full population, and because the sample is based on a subset, the data and inferences are subject to ‘sampling error’.

One of the advantages of a census is that detailed information about sub-groups within the population is more likely to be available.

A sample may be too small to provide detailed information about sub-groups.

We often look at data sets that are samples and not censuses. What are the pros and cons?