### Sample

A subset of observations from the population data used to study or analyse in order to learn about the population.

### Random sample

A sample in which all observations within the population have an equal chance of being included not influenced by bias and each selection is independent from the other selections in the sample.

### Population

The full collection of individuals or items under consideration in your statistical study. A finite population can be physically listed, e.g. a list of the books in a library. A hypothetical population is an assumed future population based on inferences made from the existing population.

### Parameter

An unknown numerical summary of a population.