OPTIONS LINESIZE=88 PAGESIZE=53 NOCENTER NODATE NONUMBER NOFMTERR;
*************************************************************************;
* PROJECT NAME: Selecting Samples without Replacement in SAS             ;
*             PROGRAM NAME        DATE                    PROGRAMMER     ;
TITLE1 "Source:lec25p7.sas  C:\ed\web\be691f\webready  12/3/98  EJS "    ;
* Description:Select a SRS of size 5 WITHOUT Rep from Pop of size 10     ;
*   keeping only the selected sample values                              ;
*   Illustrating the RETAIN statement using PUT statements               ;
*************************************************************************;


**************************************;
*** Select a simple random sample of  ;
*** 5 observations without            ;
*** replacement                       ;
*** from the 10 numbers               ;
**************************************;

DATA samp1;
 SET pop1;
 FILE PRINT ;                             * Direct output from PUT statements to OUTPUT window;
 npop=10;
 nsamp=5;
 RETAIN npop  nsamp ;
 prob=nsamp/npop;                         *proportion of observations left to select;
 rn=RANUNI(3362);                         *random number to see if current obs is selected;
 PUT /ID= npop= nsamp= prob= rn= ;        * details of data step;
 IF rn LT prob THEN DO;
   insamp=1;                              *indicator for values selected in the sample;
   nsamp=nsamp-1;                         *number left to select in the sample;
   PUT " Selected:" insamp= nsamp= npop= ;
   OUTPUT;
 END;
 npop=npop-1;

PROC PRINT DATA=samp1;
  ID id;
  TITLE2 "Table 7.1  Illustratin of SRS without Replacement with WRONG use Initial Values for RETAIN";

RUN;