How to do the diagnostic analysis of the model adjusted by the systemfit package, for example:
library(systemfit)
data("Kmenta")
eqDemand <- consump ~ price + income
eqSupply <- consump ~ price + farmPrice + trend
system <- list( demand = eqDemand, supply = eqSupply )
fitsur <- systemfit( system, "SUR", data = Kmenta, maxit = 100 )
influence.measures(fitsur)
Error in UseMethod("influence")