In SAS^® 8.1, the DOMAIN statement was added to PROC SURVEYMEANS to compute mean and total estimates for subpopulations (subgroups and domains) of the sampled population. The computation of ratio estimates within domains was added in SAS/STAT^® 9.22 (SAS^® 9.2 TS2M3). Because survey samples are from finite populations, the variance estimators for a given subgroup require all the observations in your sample, including observations that are outside the subgroup. Therefore, you should not subset your data or use the BY statement to estimate parameters for subpopulations.