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From |
Maarten buis <maartenbuis@yahoo.co.uk> |

To |
statalist@hsphsun2.harvard.edu |

Subject |
RE: st: Re: computation of R-squared with a non-linear model |

Date |
Wed, 20 May 2009 08:27:31 +0000 (GMT) |

--- "marcel spijkerman" wrote: > > > I estimate a weighted non-linear model of the > > > following form: > > > > > > y^0.5 = (a1 + a2*X)^0.5 weighted by some other > > > variable z. > > > > > > Stata reports an adjusted R-squared of 1.000. I > > > suspect this is not correct. How can compute the > > > correct adjusted R-squared using untransformed > > > variables? --- Martin Weiss wrote: > > Which command did you use for your estimation? If it > > was non-linear, -nl-? > > Show us what you typed and what the reply was... --- On Wed, 20/5/09, marcel spijkerman wrote: > I indeed typed the command: > > nl (sqrt_y = (a1 + a2X)^0.5) [aweight= hhd1564_06] > > And the answer is .... :-) It is surprising that you got output at all, as you did not specify any parameters. Anyhow, it appears that you have a convergence problem. So the next step is not to try to come up with some correct R^2, but to fix the model. You could try specifing starting values. -- Maarten Ps. -aweights- are very very very rarely the correct weight type. ----------------------------------------- Maarten L. Buis Institut fuer Soziologie Universitaet Tuebingen Wilhelmstrasse 36 72074 Tuebingen Germany http://home.fsw.vu.nl/m.buis/ ----------------------------------------- * * For searches and help try: * http://www.stata.com/help.cgi?search * http://www.stata.com/support/statalist/faq * http://www.ats.ucla.edu/stat/stata/

**Follow-Ups**:**RE: st: Re: computation of R-squared with a non-linear model***From:*marcel spijkerman <marcel_spijkerman@hotmail.com>

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