I have found MatchIt in R that does propensity score matching among 2 groups. But I have six groups that I'd like matched by age, gender, race, and a few other variables. They don't have to be individually matched groups, even frequency matched is OK with me. Can someone point me to software that handles six groups? I've been looking hard but haven't found anything. R is preferred.
TWANG package can handle weighted propensity scores, but I need a 6-way-matched dataset, which that package can't give me. It only outputs weights (I think). Thanks!