As far as I know, sum is used for numberic variables, how about the string variables?
Here is the data:
----------------------- copy starting from the next line -----------------------
Code:
* Example generated by -dataex-. To install: ssc install dataex
clear
input str54 Mediator float tempid
"negAffect5"                                             1
"posAffect4"                                             1
"negAffect2 negAffect3"                                  1
"negAffect2 negAffect5"                                  1
"negAffect3 negAffect4"                                  1
"negAffect3 negAffect5"                                  1
"negAffect4 negAffect5"                                  1
"negAffect1 negAffect3 negAffect5"                       1
"negAffect2 negAffect3 negAffect4"                       1
"negAffect2 negAffect3 negAffect5"                       1
"negAffect2 negAffect4 negAffect5"                       1
"negAffect3 negAffect4 negAffect5"                       1
"negAffect1 negAffect2 negAffect3 negAffect4"            1
"negAffect1 negAffect2 negAffect3 negAffect5"            1
"negAffect1 negAffect3 negAffect4 negAffect5"            1
"negAffect2 negAffect3 negAffect4 negAffect5"            1
"negAffect1 negAffect2 negAffect3 negAffect4 negAffect5" 1
"negAffect5"                                             2
"posAffect4"                                             2
"negAffect2 negAffect3"                                  2
end