可以随机抽取5%然后分开到两个数据集就欧克了
proc sort ;
by group;
run;
proc surveyselect data=xxx rate=0.55   outall  out=xxx;
    strata group ;
   run;
data xxx1 xxx2;
set xxx;
if selected then output xxx1; else output xxx2;
keep  group var1-varN;
run;