Introduction
Selecting random samples representative of the population is essential for research studies. Definitions, a checklist
for conducting a survey, and examples of selecting stratified random samples are provided in this paper. Annotated
examples shown determine sample size for each strata and stratify on 1, 2, and 3 variables. Before PROC
SURVEYSELECT was available, the ranuni function with several data steps was used to obtain stratified samples.
Appendix A illustrates a ranuni method to select stratified samples.