A type of non-probability sample that includes specified numbers of respondents based on percentages of specific characteristics that have been predetermined as representative of the target population.

The separation of a given population into groups on the basis of a common characteristic, such as age or sex, and the formation of a sample by selecting from each group the same proportion of the sample as that group bears to the total aggregate.

A set number of people chosen for something being studied (for example, their religious practices or their work history) who all belong to one place (for example, one city neighborhood) that is chosen at random. ace – A group of people who share certain inherited physical characteristics [adapted from SAMHSA definition]; for example, African-Americans and Native Americans are usually called races, but Southern Baptists are not.