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Re: st: finding a peak in an asymmetric curve


From   Joseph Coveney <jcoveney@bigplanet.com>
To   Statalist <statalist@hsphsun2.harvard.edu>
Subject   Re: st: finding a peak in an asymmetric curve
Date   Tue, 11 Apr 2006 21:35:05 +0900

David Harrison wrote:

Yes, why didn't I think of that form...?

Anyway, one other useful point to note. You can get a confidence
interval on the position of the maximum from the -nl- function (having
worked out how to express it as a function of the parameters) by using
-nlcom-:

nlcom ln(_b[/delta] / _b[/beta]) / (_b[/beta] - _b[/delta])

--------------------------------------------------------------------------------

The classic functional form jumps out from the scatterplot.

It still might be worthwhile to consider bootstrapping for the confidence
interval:  -nl- and -nlcom- give asymptotic approximations.

Joseph Coveney

P.S. There was a stranded close-comment in one line

predict longevity_hat */

that should be deleted

predict longevity_hat

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