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2013 Jan 13
1
R error: system is computationally singular when building GMM model
Dear,
I built the generalized method of moments model to estimate the sales rank
in the bookstore using plm package in R.
The equation is:
data1.gmm <- pgmm(dynformula(lnsales_rank ~ ln_price + avg_ham_rate +
avg_spam_rate + num_of_ham+ num_of_spam + ship_code2 +ship_code3
+ship_code4+ ship_code5+ ship_code6 + ship_ code7, lag = list(0, 0, 0,
0,0,0,0,0,0,0,0,0), log =FALSE), data=data, effect = "individual", model =
"twosteps", transformation = "ld",gmm.inst = ~ ln_price, lag.gmm =2)
However, error message: Error in solve...