Dear Catherine E Hendrick, I think your problem can be easily re-conducted to the case of Multiple treatment doses (e.g., doses of a drug). Among other see section 6.1.4 of Stuart (2010) paper https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2943670/ Stat Sci. 2010 Feb 1; 25(1): 1–21. doi:  10.1214/09-STS313 I was using CEM to pairwise compare outcomes of three groups of firms with different treatments (degree of environmental commitment ) http://www.sciencedirect.com/science/article/pii/S0959652616313804   but I miss a formal/ theoretical discussion and I will be very interested on proper guidance on this point. Cesare   From: "cem-request(a)lists.gking.harvard.edu" <cem-request(a)lists.gking.harvard.edu> To: cem(a)lists.gking.harvard.edu Sent: Saturday, 3 December 2016, 18:00 Subject: Cem Digest, Vol 83, Issue 1 Send Cem mailing list submissions to     cem(a)lists.gking.harvard.edu To subscribe or unsubscribe via the World Wide Web, visit     https://lists.gking.harvard.edu/mailman/listinfo/cem or, via email, send a message with subject or body 'help' to     cem-request(a)lists.gking.harvard.edu You can reach the person managing the list at     cem-owner(a)lists.gking.harvard.edu When replying, please edit your Subject line so it is more specific than "Re: Contents of Cem digest..." Today's Topics:   1. 2-level CEM? (Catherine E Hendrick) ---------------------------------------------------------------------- Message: 1 Date: Fri, 2 Dec 2016 15:49:08 -0600 From: Catherine E Hendrick <emily.hendrick(a)utexas.edu> To: cem(a)lists.gking.harvard.edu Subject: [cem] 2-level CEM? Message-ID:     <CAJWC3AAG_ejC3Y2S1FUo6aG2DJ4RFnSCpNh=npijS-PoNCqmbA(a)mail.gmail.com> Content-Type: text/plain; charset="utf-8" I am considering using Coarsened Exact Matching in order to study the effects of teen mothers' degree type (GED v. HS diploma) on long-term outcomes. In order to sufficiently address my research questions, it seems that I may need two levels of matching: 1) matching those who attained a GED with those who attained a HS diploma (to isolate the effects of degree type on outcomes) 2) matching teen mothers with women who began childbearing after the teenage years (to determine if diploma type effects on later outcomes are the same or different for women who began childbearing during the teenage years v. later) I haven't seen any literature using CEM that conducts two levels of matching as I am proposing. Do you know of literature where researchers have done this and/or do you see any methodological reason for NOT conducting two levels of matching, as I have proposed, when using CEM? Many thanks for any information you're able to pass along.