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weighted linear fit

 
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khickey



Joined: 13 Jul 2011
Posts: 22

PostPosted: Thu Aug 29, 2013 4:26 am    Post subject: weighted linear fit Reply with quote

Hey

I want to do a weighted linear fit (a weighted least squares fit?) to 2 columns of data (rock age, Y, and elevation of dated rock sample, X). The uncertainty in Y (age) is signficantly larger than uncertainty in X (elevation). I have error estimates for each set of data - how can I incorporate independents weights for each set of data?

In the current Fit option in DataGraph, is the weighting option applied to both the X and Y data, or just the Y data?

Thanks
Cheers
Ken
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David
Site Admin


Joined: 25 Nov 2006
Posts: 1966
Location: Chapel Hill, NC

PostPosted: Thu Aug 29, 2013 7:29 am    Post subject: Reply with quote

The weight is applied to the y data, since what is being minimized is the size of

weight*(ydata - yfunction)

David
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khickey



Joined: 13 Jul 2011
Posts: 22

PostPosted: Thu Aug 29, 2013 1:13 pm    Post subject: Reply with quote

thanks David
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