options pageno=1;
data reg;
input x rep y;
xy=x*y;
datalines;
10 1 432
20 1 334
30 1 224
40 1 199
50 1 134
60 1 125
10 2 410
20 2 403
30 2 300
40 2 280
50 2 247
60 2 225
;;
proc print;
title 'Printout of Data -  All Data';
run;
proc reg;
model y=x;
title 'Regression on All Data - Reps Kept Separate';
run;
proc sort;
by x;
proc means mean noprint;
by x;
var y;
output out=new mean=meany;
*Comment:  The previous statement takes the average of Y1 and Y2 to create
a new variable Y.  Performing regression on means provides a better
coefficient of determination';
run;
proc reg;
model meany=x;
title 'Regression on the Mean of Y';
run;