random sample

a randomly selected group of scores selected from a population.

A sample of scores is a selection from a population of scores. For instance, a sample of blood pressure scores might be taken from the population of all blood pressure scores.

A random sample is a sample where all the scores were chosen randomly.

Parameters of the random sample (such as mean and variance) can be used as estimates of the parameters of the population. In general, the larger the sample, the better the estimate, but other factors also contribute to the accuracy of the estimate.