In general, a sample is a selection from the population being studied.
When a survey is
being carried out, for example to see who might win an election, a selected
subset of people are questioned about their voting intentions, and
conclusions are then made about the whole population. The subset of
people questioned is a statistical sample. The process of taking samples
in this way is called sampling.
A small group of things that are taken
from a larger group of things and studied so that more can be said
about the nature of the larger group. For example,
if four pupils are taken
from each class in your school and their heights are measured, the
average height of all the pupils in your school can be estimated.
Inspectors in a factory will carefully examine a sample of the goods
being produced to decide whether its quality comes up to scratch.