options ls=105 nodate;

data one;
   input x1 x2 x3 y;
   cards;
  19.5  43.1  29.1  11.9
  24.7  49.8  28.2  22.8
  30.7  51.9  37.0  18.7
  29.8  54.3  31.1  20.1
  19.1  42.2  30.9  12.9
  25.6  53.9  23.7  21.7
  31.4  58.5  27.6  27.1
  27.9  52.1  30.6  25.4
  22.1  49.9  23.2  21.3
  25.5  53.5  24.8  19.3
  31.1  56.6  30.0  25.4
  30.4  56.7  28.3  27.2
  18.7  46.5  23.0  11.7
  19.7  44.2  28.6  17.8
  14.6  42.7  21.3  12.8
  29.5  54.4  30.1  23.9
  27.7  55.3  25.7  22.6
  30.2  58.6  24.6  25.4
  22.7  48.2  27.1  14.8
  25.2  51.0  27.5  21.1
  25     50    29    .
;

proc reg;
   title "Full model (p=3)";
   model y=x1 x2 x3/xpx i ss1 ;   
   test x2=x3=0;
run;

/* 
- xpx and i generate the matrices from p. 38 of course packet 
- ss1 gives sequential sums of squares
- the TEST statement compares models 1 and 4 from p. 41 of course packet
*/


proc reg;
   model y=x1 x2 x3/selection=cp;
run;

proc reg data=one;
   model y=x1/clm xpx i; /* model 1*/ 
   model y=x2/clm; /* model 2*/ 
   model y=x1 x2/clm xpx  i; /* model 6*/ 
   model y=x1-x3/clm xpx  i; /* model 4*/ 
run;