The STRATA statement specifies variables that form the strata in a stratified sample design. The combinations of categories of STRATA variables define the strata in the sample.

If your sample design has stratification at multiple stages, you should identify only the first-stage strata in the STRATA statement. See the section Specification of Population Totals and Sampling Rates for more information.

If you provide replicate weights for BRR or jackknife variance estimation with the REPWEIGHTS statement, you do not need to specify a STRATA statement.

The STRATA variables are one or more variables in the DATA= input data set. These variables can be either character or numeric. By default, strata are determined from the entire formatted values of the STRATA variables. Note that this represents a slight change from previous releases in the way in which strata are determined. Prior to SAS 9, strata were determined by using no more than the first 16 characters of the formatted values. If you want to revert to this previous behavior, you can use the TRUNCATE option in the PROC SURVEYREG statement.

Thus, you can use formats to group values into levels. See the FORMAT procedure in the Base SAS Procedures Guide and the FORMAT statement and SAS formats in SAS Language Reference: Dictionary for more information.

You can use multiple STRATA statements to specify stratum variables.

You can specify the following options in the STRATA statement after a slash (/):