# Definition:Simple Random Sample

## Definition

Let $P$ be a population.

Let $S \subsetneq P$ be a sample.

Then $S$ is a simple random sample (of size $n$) if and only if it fulfils the following criteria:

• Every individual in $P$ had an equal chance of being selected to be in $S$;
• Every $n$-combination of $P$ had an equal chance of being constructed as a potential $S$.

## Also known as

A simple random sample is also called a random sample if there is no danger of ambiguity.