I'm trying to use cem to do matching involving 3 treatments. Prof. King
(http://comments.gmane.org/gmane.comp.lang.r.matchit/393) indicated that
this can be done.
When I tried it, I got an error message -
imbalance(): 3258 <tmp>[1,1] found where void required
<istmt>: - function returned error
There was a discussion on this site on July 24 of 2013 about a similar
issue. In that case, there were only 2 treatments but a treatment of ".",
along with "1" and "2", showed up in the summary table. The suggestion was
to add "if indepvote != ." to the cem call."
While I'm sure that there are no missing values of my treatment variable, I
still tried to add the if clause to my cem call. But it didn't help. I got
another error:
. cem margins1 age, tr(approach1) if approach1 != .
option if not allowed
r(198);
Any ideas of how I can proceed?
Thanks.
Dennis Hanseman
