DM 'LOG;CLEAR;OUT;CLEAR';
OPTIONS NODATE NONUMBER NOCENTER PS=54 LS=70;

*******************************************************;
*** Systematic sample analysis for equal-sized PSUs ***;
*******************************************************;

DATA systmtc1;
  M0 = 400;     * number of secondary sampling units (SSUs) in population;
  M  = 16;      * number of SSUs in a PSU;
  n  = 3;       * number of primary sampling units (PSUs) sampled;
 
  wgt = M0/(n*M);
  DO psu = 1 to n;
  DO ssu = 1 to M;
     INPUT trees @@; OUTPUT;
  END; END;
DATALINES;
1 0 0 1 0 0 1 1 7 0 0 2 0 1 1 1 
4 0 0 2 0 6 4 2 0 4 0 2 0 0 1 1 
2 2 1 1 0 1 0 1 1 2 1 0 0 1 0 2
;

*** TOTAL = number of PSUs in the population ***;

PROC SURVEYMEANS DATA=systmtc1 TOTAL=25 MEAN CLM SUM CLSUM;
     VAR trees;
     CLUSTER psu;
     WEIGHT wgt;
TITLE 'Systematic Sample from Figure 9a';
RUN;