The first line tests whether the mean of group A is different from zero, the second whether the mean of group B is different from zero, and the third whether the difference between A and B is itself different from zero.  Beware of subtracting between confidence bounds--you could have a significant difference without the difference being greater than zero.  And it scares me a little that you have multiple groups and are using multiple t-tests to compare them two at a time.  That sort of comparison is handled a lot better by analysis of variance techniques. Steve Denham ... View more

It looks like OP did not make himself clear. data have; input value @@; cards; 1 1 4 6 7 3 2 5 7 8 9 5 3 2 6 8 9 0 9 0 9 7 6 5 4 5 7 8 9 8 ; run; %let dsid=%sysfunc(open(have)); %let n=%sysevalf(%sysfunc(attrn(&dsid,nobs))/2,ceil); %let dsid=%sysfunc(close(&dsid)); data _null_; set have end=last; array odd{&n} _temporary_; array even{&n} _temporary_; if mod(_n_,2) eq 1 then do; a+1;odd{a}=value;end;   else do; b+1;even{b}=value;end; if last then do; do i=1 to &n; put odd{i}= even{i}=; end; end; run; Ksharp Tian.Kong ... View more