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st: RE: RE: LevenbergMarquardt/summary
If you want to fit a mixture of normals, then I think Stas Kolenikov has
a program for doing this.
-findit- should locate this
Professor Stephen P. Jenkins <firstname.lastname@example.org>
Institute for Social and Economic Research
University of Essex, Colchester CO4 3SQ, U.K.
Tel: +44 1206 873374. Fax: +44 1206 873151.
> -----Original Message-----
> From: email@example.com
> [mailto:firstname.lastname@example.org] On Behalf Of Nick Cox
> Sent: 09 March 2004 10:16
> To: email@example.com
> Subject: st: RE: LevenbergMarquardt/summary
> It might be better to set this up as a -ml- problem.
> The text of Sophia Rabe-Hesketh and Brian Everitt
> discusses the two Gaussians case in detail and poses
> your case as an exercise, with hints for solution.
> Andreas Aschbacher
> > In austrian centre of physics we use Stata to do
> > LevenbergMarquardt(nl-coomand)
> > please look at my posting from january 20th with
> > heading:LevenbergMarquardt
> > short summary :the number of persons who is exposed to a little
> > dosis-interval /about 0.01 mSv/ yields in sum a curve which
> is mostly
> > composed of
> > two sometimes three humps.above each dosis-interval /about
> > 0.01 mSv/there is
> > the number
> > of persons as function. with Stata it was possible to show
> that in 397
> > cases we have the sum of Gauß-distributions.the results are
> > very useful.
> > because of lv-command we can talk here about skewness of our curves.
> > median-test is also used very often.we decided to take Stata
> > to use for our
> > work becaue it is so easy to split in subgroups and make
> tests after.
> > -
> > My question: if I have two Gauß-curves to be fitted,it is no
> > problem to find
> > values
> > in Stata.but if I have to find three Gauß-curves,I mean to
> > come from 1) to
> > 2) for
> > example
> > 1)
> > Ai for i = 1,2.... means amplitude
> > A1 12209.2
> > µ1 4.382678
> > delta1 0.3097696
> > A2 21683.69
> > µ2 4.200002
> > delta2 0.550282
> > 2)
> > A1 11509.05
> > µ1 4.403567
> > delta1 0.3050716
> > A2 1305.195
> > µ2 4.18422
> > delta2 1.100233
> > A3 21540.19
> > µ3 4.198081
> > delta3 0.5104234
> > I need long time to try.with another famous statistical
> > software I have
> > possibility to make
> > constraints and it takes no long time.
> > I "fear the worst" that someone(my boss?) will ask me during my
> > presentation,if there are add-inns in Stata to use or
> > user-written-programs that I have
> > this feature.
> > it is a pity that it is not possible for me to come to 2nd
> > German Stata
> > User's meeting in April.
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