data trees;
input name:$8. height;
cards;
Maple 123
Maple 78
Maple 90
Elm 155
Elm 65
Elm 90
Elm 120
Birch 100
Birch 30
Maple 111
run;

proc means data=trees nway noprint;
class name;
var height;
output out=meansd mean=meanheight std=sdheight;
run;

data _NULL_;
set meansd end=last;
call symput('mean'||left(_N_),meanheight);
call symput('sd'||left(_N_),sdheight);
call symput('name'||left(_N_),trim(name));
if last then call symput('numspecies',_N_);
run;

%PUT _USER_;

%MACRO treestandardizer;
data final;
set trees;
%DO i = 1 %TO &numspecies;
if name="&&name&i" then stheight=(height-&&mean&i)/&&sd&i; 
%END;
%MEND;

options mprint;
%treestandardizer

proc print;