You can certainly specify more than 2 treatments. The error you’re getting is because –imbalance- is set up to compare between only two treatment groups. As for the k2k error, I don’t get that error. However, I do find that k2k does not produce 1:1 matches when there are more than two treatments.

 

From: cem-bounces@lists.gking.harvard.edu [mailto:cem-bounces@lists.gking.harvard.edu] On Behalf Of Erik Cleven
Sent: Wednesday, November 11, 2015 3:59 PM
To: cem@lists.gking.harvard.edu
Subject: [cem] cem error message

 

I am attempting to run cem with an ordinal treatment variable that has four values. I get the following error message:

 

imbalance():  3258  <tmp>[1,1] found where void required
                 <istmt>:     -  function returned error
r(3258);

 

A previous reply to someone who also got this error message said to update cem because there was a bug with the imb function.

 

I updated and now recieve this message:

 

NOTE: Treatment has must have only 2 levels to compute distance and weights. In addition, k2k cannot be used.

 

Does this mean cem cannot be used with more than 2 treatments? Actually I have a continuous treatment but I recoded it to a variable with four levels. 

 

Thanks!

Erik

 

--

Erik Cleven, PhD

Assistant Professor

Department of Politics

Saint Anselm College

100 Saint Anselm Drive

Manchester, NH 03102-1310

 

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