[cem] k2k option for CEM valid with more than 2 treatment groups

Hi - I am working on an analysis in STATA with the cem module that considers four duration groups (treatment groups) and I'd like to balance these 4 groups based on one covariate (number of prior medications). I was able to run the following statement when I consider only two duration groups (dur). In that case, the number of matched observations is reduced to the sum of the smallest number with a given number of prior medications across the duration groups (using the k2k option). However, when I run the statement with the 4 duration groups, the number of matched observations is not reduced, which would make me think that it isn't running correctly or isn't appropriate. Please advise. cem numpriorbio2 , treatment(dur) k2k noimb Thank you for your help, Heather Heather J. Litman, PhD Lead Biostatistician Corrona, LLC. hlitman@corrona.org<mailto:hlitman@corrona.org> Office Phone: (508) 408-5422 Mobile Phone: (617) 462-6631 Fax: (773) 347-1689 [cid:image001.jpg@01D0AE63.A5CF3580] This communication may contain information that is proprietary, confidential, or exempt from disclosure. If you are not the intended recipient, please note that any other dissemination, distribution, use or copying of this communication is strictly prohibited. Anyone who receives this message in error should notify the sender immediately by telephone or by return e-mail and delete it from his or her computer. --------------------------------------------------------------------------------------- This email has been scanned for email related threats and delivered safely by Mimecast. For more information please visit http://www.mimecast.com ---------------------------------------------------------------------------------------