How can I solve this issue?
I did use this code before and it was working back then. But I am experiencing this problem now.
Also, it works well using random/fixed effect estimations.
Thanks!
Yes, they all work.
I do get the result of the summary function for fixed/random effect models on this data.
I am also getting the result of the summary function for GMM using another dataset.
I get the same error when I want to run the following code:
mtest(GMM, order = 2, vcov = NULL)
It does also work for order = 1, but not for order = 2
I figured the problem is related to AR(2). I only have 4 years of data, whereas in order to have the AR(2) 5 years is needed. Since "summary" couldn't report AR(2), the error was coming up.