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Re: linfit and regress questions [message #56766 is a reply to message #56693]

Tue, 13 November 2007 08:14

Craig Markwardt
Messages: 1869
Registered: November 1996

Senior Member

rlayberry@hotmail.com writes:
> On 13 Nov, 03:16, Craig Markwardt
> <craigm...@REMOVEcow.physics.wisc.edu> wrote:
>> hradilv <hrad...@yahoo.com> writes:
>>
>>> Transform the data?
>>
>>> mhat = total(x*(y-c1))/total(x*x)
>>
>> Of course this all assumes the data are meant to be equally weighted
>> (no error bars, or all error bars are equal).
>>
>
> and does anyone know how the chi-sq or any other goodness of fit
> paramater would be calculated?

Do you mean, how to compute the chi-square value? Probably something
like,
TOTAL( ((Y-MHAT*X)/ERROR)^2 )

But you've never really specified what you are trying to do. Why not
just use a fitting program like MPFITFUN or CURVEFIT and specify
whatever model and/or error bars that you want?

Craig

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[Message index]

		linfit and regress questions By: rlayberry on Sun, 11 November 2007 08:27
		Re: linfit and regress questions By: Craig Markwardt on Tue, 13 November 2007 08:14
		Re: linfit and regress questions By: rlayberry on Tue, 13 November 2007 02:24

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