data("EmplUK", package = "plm")
ar <- pgmm(dynformula(log(emp) ~ log(wage) + log(capital) +
log(output), list(2,1,2,2)), data = EmplUK, effect = "twoways", model = "twosteps", gmm.inst = ~ log(emp), lag.gmm = list(c(2,99)))
mtest(ar, 1)
mtest(ar, 2, vcovHC)
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