If you specify the ALLOC= option in the STRATA statement, PROC SURVEYSELECT allocates the total sample size among the strata according to the method you request. You specify the total sample size in the SAMPSIZE=n option in the PROC SURVEYSELECT statement.

PROC SURVEYSELECT provides proportional allocation (ALLOC=PROP), optimal allocation (ALLOC=OPTIMAL), and Neyman allocation (ALLOC=NEYMAN). See Lohr (2009), Kish (1965), and Cochran (1977) for more information about these allocation methods. Alternatively, you can directly specify the allocation proportions by using the ALLOC=(values) option or the ALLOC=SAS-data-set option. Then PROC SURVEYSELECT allocates the total sample size among the strata according to the proportions that you specify.