A selection that is chosen randomly (purely by chance, with no predictability).
Every member of the population being studied should have an equal chance of being selected.
Example: you want to survey 100 people at a football match about their main job. Asking just people in one area might give poor results as there may be a group of workmates there! So instead you can make a list using randomly chosen seat numbers from the whole stadium, then go and find each seat and interview the person there.
