indicator weighting function
Examples
data(mpdta)
dta <- subset(mpdta, year==2007)
X <- model.matrix(~lpop, data=dta)
X <- indicator(X, X[1,])
indicator weighting function
data(mpdta)
dta <- subset(mpdta, year==2007)
X <- model.matrix(~lpop, data=dta)
X <- indicator(X, X[1,])