You provide the stratum certainty size values in the secondary input data set variable _CERTSIZE_. The CERTSIZE option is available for METHOD=PPS and METHOD=PPS_SAMPFORD.
After identifying the certainty units, PROC SURVEYSELECT selects the remainder of the sample according to the method specified in the METHOD= option. In certainty selection, PROC SURVEYSELECT automatically selects all sampling units with size measures greater than or equal to the stratum certainty size values. See the section Secondary Input Data Set for details. Use the CERTSIZE option when you have already named the secondary data set in another option, such as the SAMPSIZE= SAS-data-set option. Requests certainty selection, where the certainty size values are provided in the secondary input data set. You can specify the following options in the PROC SURVEYSELECT statement. Table 87.1 PROC SURVEYSELECT Statement Options Descriptions follow in alphabetical order. Table 87.1 lists the options available with the PROC SURVEYSELECT statement. You can name only one secondary input data set in each invocation of the procedure. See the descriptions of the SAMPSIZE=, SAMPRATE=, MINSIZE=, MAXSIZE=, CERTSIZE=, and CERTSIZE=P= options for more information. You can also specify stratum sampling rates, minimum size measures, maximum size measures, and certainty size measures in the secondary input data set. You can use the SAMPSIZE= n option to specify the sample size, or you can use the SAMPSIZE= SAS-data-set option to name a secondary input data set that contains stratum sample sizes. You must specify the sample size or sampling rate unless you request a method that selects two units from each stratum ( METHOD=PPS_BREWER or METHOD=PPS_MURTHY). If you do specify a SIZE statement and do not specify a selection method, PROC SURVEYSELECT uses probability proportional to size selection without replacement ( METHOD=PPS).
If you do not specify a selection method, PROC SURVEYSELECT uses simple random sampling ( METHOD=SRS) if there is no SIZE statement. The PROC SURVEYSELECT statement also specifies the sample selection method, the sample size, and other sample design parameters. If you do not name an OUT= output data set to contain the sample of selected units, the procedure still creates an output data set and names it according to the DATA n convention. If you do not name a DATA= input data set, the procedure selects the sample from the most recently created SAS data set. The PROC SURVEYSELECT statement invokes the procedure and optionally identifies input and output data sets.
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