> -----Original Message-----
> From: [email protected] [mailto:owner-
> [email protected]] On Behalf Of Li, Shaling (lis1)
> Sent: Saturday, September 03, 2005 4:01 PM
> To: [email protected]
> Subject: st: Why does TRUNCREG cannot find the MLE estimate?
>
> Dear Statalist members,
>
> I use TRUNCREG command to run regression with truncated sample. My
> regression is to regress return on deps, a bivariate regression.
Return is
> right-skewed with a fat tail and deps is left-skewed also with a fat
tail.
>
> Model: Return = a+ b*deps + error ;
> Truncation point: return = 0;
> My command is "truncreg return deps, ll(0)" and "truncreg return deps,
> ul(0)"
>
> For the right-truncated sample, it works well and produce the same
results
> as I could get from SAS. But for the left-truncated sample, STATA shows
> that it "could not calculate numerical derivatives, missing values
> encountered" (showed below). SAS also fails to generate any stable
results
> for the left-truncated sample (either fail to generate a result as does
> STATA, or generate random results
Hi,
I you can't fit the left truncated sample with STATA or SAS I
suggest you try the little truncated regression example program
on the AD Model Builder website. ADMB uses exact derivatives calculated
by automatic differentiation techniques. This makes it very stable
numerically. You can find the TRUNCREG example on the page
http://otter-rsch.com/examples.htm
Please let me know if you find it useful.
Dave
--
David A. Fournier
P.O. Box 2040,
Sidney, B.C. V8l 3s3
Canada
http://otter-rsch.com
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