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From |
"Nick Cox" <n.j.cox@durham.ac.uk> |

To |
<statalist@hsphsun2.harvard.edu> |

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 n.j.cox@durham.ac.uk 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. * * For searches and help try: * http://www.stata.com/support/faqs/res/findit.html * http://www.stata.com/support/statalist/faq * http://www.ats.ucla.edu/stat/stata/

**Follow-Ups**:**st: RE: RE: LevenbergMarquardt/summary***From:*"Stephen P Jenkins" <stephenj@essex.ac.uk>

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