Dear all,
I intend to use a matching procedure on a project where, because of the nature of my cases, weights of control units should be all kept at 1. Reading the manuals and articles I realized that the way to do it was using CEM and applying the function k2k.However, I couldn't get it to work as described. When I run the command matchit(x, ..., k2k=TRUE), it returns a matrix that, when extracted into a data-frame, still contains weights and a different number of treated and control units - even though no error messages are shown. This happens both to my data and when running the lalonde demo script. The result of the matching is exactly the same as that obtained when k2k=FALSE. I tried to go back to the "cem" package and run the demo script there on LL with k2k - using first the command cem(x,... k2k=TRUE) and also doing the matching first and applying k2k(cem.match,...) afterwards. In both cases there's the error message "In min(x, na.rm = TRUE) : no non-missing arguments to min; returning Inf", and the resulting matrix is still exactly the same as that obtained without setting k2k to TRUE.
Thank you in advance for the help.
Best regards,
Bruno Castanho e Silva
Hi,
I'm new to matching and to MatchIt.
I'm interested in "one-to-one exact matching" in which the matched
samples are of equal size.
When I use...
matchit(formula = treat ~ MARIEE + AGE + NOBLE, data = my.data.test,
method = "exact", discard = "both", ratio = 1)
...I get samples with different sizes
Sample sizes:
Control Treated
All 770 524
Matched 671 494
Unmatched 99 30
Is it possible to get one-to-one exact matching (with equal size samples).
Thanks,
b. coulmont
--
Baptiste Coulmont
http://coulmont.com/en/
