STRATA Keyword (CSPLAN command)

STRATA is used to identify stratification variables whose values represent nonoverlapping subgroups. Stratification is typically done to decrease sampling variation and/or to ensure adequate representation of small groups in a sample.

If STRATA is used, CSSELECT draws samples independently within each stratum. For example, if region is a stratification variable, separate samples are drawn for each region (for example, East, West, North, and South). If multiple STRATA variables are specified, sampling is performed within each combination of strata.

varlist. Stratification variables.