Dear All, I have a longitudinal data and in order to run multiple imputations on it I am following the UCLA tutorials which first convert the long form to wide form and then impute and convert it back to long form. However, they have 6 visits per patient but in my case every patient has different number of visits since severe patients were followed every month while moderates were followed every 3 months for a year. I would really appreciate any help. VISIT Frequency Percent Frequency Percent ----------------------------------------------------------   1      61 20.68 61 20.68   2      53 17.97 114 38.64   3      46 15.59 160 54.24   4      45 15.25 205 69.49   5      45 15.25 250 84.75   6     45 15.25 295 100.00 proc sort data = dp_miss;   by subj visit; run; data wide;   set dp_miss;   array yt(6);   array xt(6);   by subj;   retain yt xt;   if first.subj then do i = 1 to 6;   yt(i) = .; xt(i) = .;   end;   yt(visit) = y;   xt(visit) = x1;   if last.subj;   drop visit y x1 i; run; proc print data = wide (obs=10) noobs; run; Also, I will be ruining cluster analysis picking a few variables, so is it better to impute just those variables or the entire dataset? Thanks Tasneem Multiple Imputation in SAS, Part 2 ... View more