Simple Random Sampling

The SURVEYSELECT Procedure

Simple Random Sampling

The method of simple random sampling (METHOD=SRS) selects units with equal probability and without replacement. Each possible sample of n different units out of N has the same probability of being selected. The selection probability for each unit equals n/N. When you request stratified sampling with a STRATA statement, PROC SURVEYSELECT selects samples independently within strata. The selection probability for a unit in stratum h equals n_h/N_h for stratified simple random sampling.

PROC SURVEYSELECT uses Floyd's ordered hash table algorithm for simple random sampling. This algorithm is fast, efficient, and appropriate for large data sets. Refer to Bentley and Floyd (1987) and Bentley and Knuth (1986). For additional information on simple random sampling algorithms, refer to McLeod and Bellhouse (1983) and Fann, Muller, and Rezucha (1962).

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