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From: Patrick Alken <patrick.alken@colorado.edu>
To: gsl-discuss@sourceware.org
Subject: Re: computing R-squared with gsl_multifit
Date: Wed, 26 Sep 2007 16:20:00 -0000	[thread overview]
Message-ID: <20070926162005.GA27449@hippogriff.physics.drexel.edu> (raw)
In-Reply-To: <m3ps054e88.wl%bjg@network-theory.co.uk>

> A question: is the formula the same for both weighted and unweighted
> fits?

No, unfortunately.

R^2 = 1 - chisq / Sum [ w_i * (y_i - mean(y))^2 ].

In the case of weighted data, the mean(y) is also a weighted mean:

mean(y) = 1/sum [ w_i ] * sum [ w_i y_i ]

I looked at the GNU R source to verify all this.

> 
> -- 
> Brian Gough
> 

  parent reply	other threads:[~2007-09-26 16:20 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-09-25 19:46 Patrick Alken
2007-09-26 15:52 ` Brian Gough
2007-09-26 16:18   ` Dirk Eddelbuettel
2007-09-26 16:26     ` Patrick Alken
2007-09-26 16:43       ` Dirk Eddelbuettel
2007-09-26 16:20   ` Patrick Alken [this message]
2007-10-02  8:35     ` Brian Gough

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