Can anyone tell me what the cutpoint parameter c(x) means for a character variable under the CEM matching procedure? I am using Spacegraph to identify potential matching solutions and dialog box associated with one of the solutions I click on in the graph shows this command:

cem(treatment="trt", data=kids, drop=c("readscore7"), cutpoints=list( aptitude=c(5), female=c(0,0.5,1), readscore6=c(38, 57.67, 77.33, 97), var4=c(1)), keep.all=TRUE,eval.imbalance=TRUE, L1.breaks=sp2$raw.profile$medianCP )

I know that for continuous variables, c(5) would cut the variable as closely as possible into 4 equally sized intervals. However aptitude is a character variable ("VeryWeak","Weak","Fair","Strong" or "VeryStrong"). I don’t know what c(5) means in this context, but if I change the value in the parentheses it doesn’t appear that the matching solution changes at all. What does c(5) mean in this context?

Thanks to the developers for making this new matching tool available!  

Bridget Lavelle, Ph.D.

Senior Research Manager

Program Research and Evaluation Section

Research and Data Analysis Division

Department of Social and Health Services

PO Box 45204 Olympia, WA  98504-5204

Fax:  (360) 902-0705

Email:  Bridget.Lavelle@dshs.wa.gov

Telephone:  (360) 902-0741