quartiles (or x-tiles) for the lazy

data composite;
set data.composite;
proc rank groups=4 out=ranked;
var srcalc srprot sriron srmagnes srphos srzinc srvitc srvitd packyrs bmi;
ranks rank_srcalc rank_srprot rank_sriron rank_srmagnes rank_srphos rank_srzinc rank_srvitc rank_srvitd rank_packyrs rank_bmi;
run;