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SAS FAQ 
How do I analyze survey data with a stratified random sampling with allocation to strata design?

This example is taken from Levy and Lemeshow's Sampling of Populations.

page 167 stratified random sampling:  allocation of sample to strata
This example uses the jacktwn data set.

proc surveymeans data = jacktwn n = secondjt sum mean;
  strata stratum;
  weight sampwt;
  var twin;
run;

The SURVEYMEANS Procedure

            Data Summary

Number of Strata                  18
Number of Observations           831
Sum of Weights                256998


                               Statistics

                               Std Error
Variable            Mean         of Mean             Sum         Std Dev
------------------------------------------------------------------------
TWIN            0.101384        0.014757           26055     3792.630892
------------------------------------------------------------------------

proc surveymeans data = jacktwn n = secondjt mean sum;
  strata stratum;
  weight sampwt;
  by quart1;
  var twin;
run;

QUART1=1

The SURVEYMEANS Procedure

            Data Summary

Number of Strata                   6
Number of Observations           329
Sum of Weights                 63937

                               Statistics

                               Std Error
Variable            Mean         of Mean             Sum         Std Dev
------------------------------------------------------------------------
TWIN            0.300042        0.041655           19184     2663.269969
------------------------------------------------------------------------

QUART1=2

The SURVEYMEANS Procedure

            Data Summary

Number of Strata                   6
Number of Observations           369
Sum of Weights                127874

                               Statistics

                               Std Error
Variable            Mean         of Mean             Sum         Std Dev
------------------------------------------------------------------------
TWIN            0.052692        0.021093     6737.906748     2697.198135
------------------------------------------------------------------------

QUART1=3

The SURVEYMEANS Procedure

            Data Summary

Number of Strata                   6
Number of Observations           133
Sum of Weights                 65187

                               Statistics

                               Std Error
Variable            Mean         of Mean             Sum         Std Dev
------------------------------------------------------------------------
TWIN            0.002051        0.001950      133.686957      127.139200
------------------------------------------------------------------------

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