/****************************************************************/
/*          S A S   S A M P L E   L I B R A R Y                 */
/*                                                              */
/*    NAME: SVREX9                                              */
/*   TITLE: Documentation Example 9 for PROC SURVEYREG          */
/* PRODUCT: STAT                                                */
/*  SYSTEM: ALL                                                 */
/*    KEYS: regression, survey sampling, resampling             */
/*    KEYS: domain analysis, replication                        */
/*    KEYS: unequal weighting, linear model                     */
/*   PROCS: SURVEYREG                                           */
/*    DATA:                                                     */
/*                                                              */
/* SUPPORT: Tony An                                             */
/*     REF: PROC SURVEYREG, Example 9                           */
/*                                                              */
/*    MISC: Variance Estimate Using the Jackknife Method        */
/*                                                              */
/****************************************************************/

data IceCream;
   input Grade Spending Income Kids @@;
   datalines;
7   7  39  2   7   7  38  1   8  12  47  1
9  10  47  4   7   1  34  4   7  10  43  2
7   3  44  4   8  20  60  3   8  19  57  4
7   2  35  2   7   2  36  1   9  15  51  1
8  16  53  1   7   6  37  4   7   6  41  2
7   6  39  2   9  15  50  4   8  17  57  3
8  14  46  2   9   8  41  2   9   8  41  1
9   7  47  3   7   3  39  3   7  12  50  2
7   4  43  4   9  14  46  3   8  18  58  4
9   9  44  3   7   2  37  1   7   1  37  2
7   4  44  2   7  11  42  2   9   8  41  2
8  10  42  2   8  13  46  1   7   2  40  3
9   6  45  1   9  11  45  4   7   2  36  1
7   9  46  1
;

data IceCream;
   set IceCream;
   if Grade=7 then Prob=20/1824;
   if Grade=8 then Prob=9/1025;
   if Grade=9 then Prob=11/1151;
   Weight=1/Prob;
run;

title1 'Ice Cream Spending Analysis';
title2 'Use the Jackknife Method to Estimate the Variance';
proc surveyreg data=IceCream
   varmethod=JACKKNIFE(outweights=JKWeights);
   strata Grade;
   class Kids;
   model Spending = Income Kids / solution;
   weight Weight;
run;

title 'The Jackknife Weights for the First 6 Obs';
proc print data=JKWeights (obs=6);
run;