proc corr data = a alpha nomiss;
    var c1-c20;
    run;

proc factor data = a scree rotate = promax;
var c1-c20;
run;

proc factor data = a scree rotate = promax;
var c2 c4 c5 c6 c15;
run;

proc corr data = a alpha;
var c2 c4 c5 c6 c15;
run;

proc corr data = a alpha nomiss;
var c2 c4 c5 c6 c15;
run;