The SURVEYFREQ Procedure

Output Data Sets

Subsections:

You can use the Output Delivery System to create a SAS data set from any piece of PROC SURVEYFREQ output. For more information, see the section ODS Table Names and Example 97.3.

PROC SURVEYFREQ also provides an output data set that stores the replicate weights for BRR or jackknife variance estimation and an output data set that stores the jackknife coefficients for jackknife variance estimation.

Replicate Weight Output Data Set

If you specify the OUTWEIGHTS= method-option for VARMETHOD=BRR or VARMETHOD=JACKKNIFE , PROC SURVEYFREQ stores the replicate weights in an output data set. The OUTWEIGHTS= output data set contains all observations from the DATA= input data set that are valid (used in the analysis). A valid observation must have a positive value of the WEIGHT variable. A valid observations must also have nonmissing values of the STRATA and CLUSTER variables unless you specify the MISSING option in the PROC SURVEYFREQ statement. For information about valid observations, see the section Data Summary Table.

The OUTWEIGHTS= data set contains the following variables:

  • all variables in the DATA= input data set

  • RepWt_1, RepWt_2, $\ldots $, RepWt_n, which are the replicate weight variables, where n is the total number of replicates in the analysis

Each replicate weight variable contains the replicate weights for the corresponding replicate. Replicate weights equal zero for those observations not included in the replicate.

After the procedure creates and stores replicate weights for a particular input data set and survey design, you can use them again in subsequent analyses, either in PROC SURVEYFREQ or in another survey procedure. You use a REPWEIGHTS statement to provide replicate weights to the procedure.

Jackknife Coefficient Output Data Set

If you specify the OUTJKCOEFS= method-option for VARMETHOD=JACKKNIFE , PROC SURVEYFREQ stores the jackknife coefficients in an output data set. The OUTJKCOEFS= output data set contains one observation for each replicate. The OUTJKCOEFS= data set contains the following variables:

  • Replicate, which is the replicate number for the jackknife coefficient

  • JKCoefficient, which is the jackknife coefficient

  • DonorStratum, which is the stratum of the PSU that was deleted to construct the replicate, if you specify a STRATA statement

After the procedure creates jackknife coefficients for a particular input data set and survey design, you can use the OUTJKCOEFS= method-option to store these coefficients and then use them again in subsequent analyses, either in PROC SURVEYFREQ or in another survey procedure. You use the JKCOEFS= option in the REPWEIGHTS statement to provide jackknife coefficients for the procedure.