proc means data=camel.p mean std noprint;
var pay;
output out=camel.p_cshu0(keep=mean1 std1) mean=mean1 std=std1;
run;
data _null_;
    set camel.p_cshu;
    call symputx('mean0',mean1);
    call symputx('std0',std1);
run;
data camel.chuli;
    set camel.p;
    if abs(pay-&mean1.)>2*&std1. then delete;
run;