Predetermined subsample size

[igormarchetti]

Is it possible to specify the sample size of the two groups that I'm trying to match for specific covariates? I've managed to obtain two subgroups of the same size, but I would find it very usesful to calibrate to a predetermined sample size. Is it currently possible with the MatchIt package?

[ngreifer]

You can't with MatchIt, but you can using MatchingFrontier. It integrates with MatchIt to allow you to perform matching using MatchIt then discard one pair at a time until you reach your desired sample size, opun which you can extract the matched sample. See here for general information on the package. The functionality I mentioned is described here.