Finite subset of data chosen based on a systematic process applied to all individuals in a population and considered to be representative of a population or a phenomenon to study.

### Properties

- The first subject on a list is chosen at random; the following subjects are chosen in a systematic way by applying a rule where the length of the interval between the chosen subjects is fixed at the start. This length depends on the range of a population and the number of elements desired in the sample.
- We can therefore easily predetermine the size and the elements that make up the sample.
- The sample is distributed in equal proportions in the population.
- However, with its characteristic of regular intervals to choose individuals, this method does not guarantee that the sample will be perfectly representative of the target population.