data covar_ex ;
 input group x y @@ ;
 cards ;
 1 1 1  1 2 3  1 4 4  1 7 7 
 2 10 15  2 20 5  2 40 57  2 70 40 
 ;
 proc print;
 run;
proc sort ; by group ; run;
proc plot ; plot y*x ; by group ; run;
proc sgplot ; scatter x=x y=y;
by group ;run;
proc corr cov ;
 var x y ;
 by group ;
 run ;