So when using the
GenMatch function to generate optimal weight coefficients for use in the
Match() function. What do these values in the weight.matrix represent?
For example, if we work through the example from the
library(Matching) data(lalonde) attach(lalonde) X = cbind(age, educ, black, hisp, married, nodegr, u74, u75, re75, re74) BalanceMat <- cbind(age, educ, black, hisp, married, nodegr, u74, u75, re75, re74, I(re74*re75)) genout <- GenMatch(Tr=treat, X=X, BalanceMatrix=BalanceMat, estimand="ATE", M=1, pop.size=16, max.generations=10, wait.generations=1) genout$Weight.matrix
We get a value of 296.8 for our age variable. What does this number represent, where does it come from/how is it calculated, is it in someway related to the variance of the data?
And leading on from this, how would one alter this age weighting value, such that matching occurs with +-5 years ?
Jasjeet Singh Sekhon wrote the matching package for R, but both reference data contains no description on the weight.matrix