filename ps467 'ps467.dat';
options center linesize=76 nodate;
data;
infile ps467;
input @4 t y;
if t=1 then d1=1; else d1=0;
if t=2 then d2=1; else d2=0;
if t=3 then d3=1; else d3=0;
if t=4 then d4=1; else d4=0;
e1=d1-d4;
e2=d2-d4;
e3=d3-d4;
c1=d1-d2;
c2=d1+d2-2*d3;
c3=d1+d2+d3-3*d4;
proc print;
proc reg;
  model y=d1 d2 d3/corrb;
  model y=e1 e2 e3/corrb;
  model y=c1 c2 c3/corrb;
run;
quit;