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 $n$) iff it fulfils the following criteria:


 * The process used to select the individuals of $S$ from $P$ was random;


 * 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.