# st: RE: LevenbergMarquardt/summary

 From "Nick Cox" <[email protected]> To <[email protected]> Subject st: RE: LevenbergMarquardt/summary Date Tue, 9 Mar 2004 10:16:12 -0000

```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.

http://www.stata.com/bookstore/statanalyses.html

Nick
[email protected]

Andreas Aschbacher

> In austrian centre of physics we use Stata to do
> LevenbergMarquardt(nl-coomand)
> please look at my posting from january 20th with
> 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 Gau�-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 Gau�-curves to be fitted,it is no
> problem to find
> values
> in Stata.but if I have to find three Gau�-curves,I mean to
> come from 1) to
> 2) for
> example
>
> 1)
> Ai for i = 1,2.... means amplitude
> A1	12209.2
> �1	4.382678
> delta1	0.3097696
> A2	21683.69
> �2	4.200002
> delta2	0.550282
>
> 2)
> A1	11509.05
> �1	4.403567
> delta1	0.3050716
> A2	1305.195
> �2	4.18422
> delta2	1.100233
> A3	21540.19
> �3	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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