Answer 1

A subset of a population used to represent the population in statistical analysis. Samples are almost always random, which means that all individuals in the population are equally likely to be chosen for the sample / Or / One or more observations drawn from a larger collection of observations or universe (population)

Answer 2

One or more observations drawn from a larger collection of observations or universe (population).

Answer 3

A small collection of items or material taken from a large population and intended to represent the population. Used to estimate the parameters (e.g. average, standard deviation) of the population. See guides to sampling and sample size calculation.