Hi list, has anyone succeeded in using pgmm() on any dataset besides Arellano/Bond's EmplUK, as shown in the vignette? Whatever I try, I eventually get a runtime error because of a singular matrix at various points in pgmm.diff() (which gets called by pgmm()).
For example, when estimating a "dynamic" version of the Grunfeld data: data(Grunfeld, package="Ecdat") grun <- pgmm(dynformula(inv ~ value + capital, lag=list(1,1,1), log=T), data=Grunfeld, gmm.inst=~log(inv), lag.gmm=list(c(2,5)), model="twosteps") Error in solve.default(suml(A2)) : system is computationally singular: reciprocal condition number = 8.83721e-21 I read all the documentation available and tried stepping through the source code, but pgmm.diff() is not exactly the easiest function to understand, especially given R's suboptimal debugging facilities. Please let me know if you had better luck with your estimation. Thanks, Richard ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
