can anyone help this is urgent

[mkpk]

can anyone help me find a way to calculate the proportion of subjects in trt1 per visit receiving placebo from a dataset containing  variables ..usubjid, trt1,trt2 .avisit .avisitn .pbo and drug.

i am supposed to plot this proportion as another graph. so i need i need to add this proportion data to the main dataset in order to validate.

please suggest this is urgent . i tried with merge it is not working for some reason. can anyone guide me with proc sql.

[sandyming]

Something like this?

proc sql;

      create table temp as

       select a.usubjid, a.avisitn, count1/count2 as pct

           (select usubjid, avisitn, count(usubjid) as count2 from dataset where trt1 ne '' group by avisitn ) a

               left join

           (select usubjid,avisitn,count(usubjid) as count1 from dataset where trt1 ne '' and drug='PLACEBO'  group by avisitn) b

     where a.avisitn=b.avisitn;

quit;

then you can merge with original with usubjid avisitn....