On Wed, 4 Nov 2009, Gal Wettstein wrote:

> I am having some problems with GMM...

One more tip for debugging GMM,  Try calculating your "GMM
residual" outside of the GMM block and see what it looks like.

It should not contain any NAs other than for lost observations at
the beginning and/or end of the sample, associated with taking
leads and lags.  I suspect this condition is not met in your case.

A construction that arises in a few places in your "e1" and "e2"
series is:

(CONS_DETREND - lambda*GDP_DETREND)^(gamma - 1)

I assume that "DETREND" means that these series are either first
differences or residuals from some sort of regession on time;
either way the series will include both positive and negative
values.  Now you initialize lambda to 0.05 and gamma to 0.1.
This means that you're almost certainly trying to take negative
numbers to a fractional power.  Bzzt!  This would result in a
complex number and is not legal in regular floating-point
arithmetic.  In gretl it will produce an NA.

Allin Cottrell

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