Subset of a population selected according to some important characteristic. RT stratification.

A group of people or things chosen so that certain levels or smaller groupings (like certain ages, incomes, or diagnoses) are kept together and a set number of people or things from each level are in the larger group. A stratified “random sample” chooses the people or things within each grouping or level by chance, but decides ahead of time how many people or things there will be within each level and what the levels will be.

The sample that is formed when independent random samples are selected from each stratum (or cell) of a stratified sampling design. (Also see stratification.)

A type of probability sample that is made more representative of the target population by dividing the target population into groups called strata and taking simple random samples from each of the strata.

a sample taken by first dividing the population (e.g. a field) into subsections, then taking samples within each subsection

A sample that is obtained by dividing the population into groups so that each item in the population belongs to only one group.

Structuring of a sample to include predetermined numbers of items with various characteristics. EX: Four or five times the number of men may be sampled in a study of TMD because the condition is more uncommon among men than women. [See also sample

the population is divided into strata and a random sample is taken from each stratum

A sample obtained by combining simple random samples taken from several disjoint subpopulations or strata.

probability sample that is determined by dividing the population into groups or strata defined by the presence of certain characteristics and then random sampling from each of the strata. This is a good way to make sure that a student sample is racially diverse (for instance).

A sampling technique in which the population of transactions is divided into separate groups based on transaction amount. Each group is sampled separately.

Subsets of sampling units are selected separately from different strata, rather than from the frame as a whole.