[proFit-list] Calculation of errors in fits

[Arthur Rowe]

Absolutely right, Kurt. But - Saskia - pro Fit also makes it  
exceptionally easy to do a more complete error analysis, once you have  
found (usually by repeat analyses) what the errors are in the data  
points. You simply select that option in the Fit. Using 500 iterations  
you get a parameter distribution (for n parameters) and after binning  
and plotting out you can have a good idea as to whether usual  
assumptions (gaussian) make sense or not. Without going into the  
particular science we were working on, you can see by inspection of  
some of such plots that it is perfectly possible for distributions are  
VERY non-Gaussian indeed (http://dx.doi.org/10.1002/mabi.201000065).

The ease with which you can do this sort of thing is a major  
plus-feature of pro Fit.

Kind regards

Arthur

************************************************************************ 
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Arthur J Rowe
Professor of Biomolecular Technology / Director NCMH Business Centre
School of Biosciences
University of Nottingham
Sutton Bonington
Leics LE12 5RD

TEL:  0115 9516156
FAX:  0115 0516157
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On Aug 4, 2010, at 04:22, pro Fit Support wrote:

> Dear Saskia
>
> For a description of that topic, see page 115 (bottom) and 116 (top)  
> of the manual (http://www.quansoft.com/manual/proFit_61_Handbook.pdf)
>
> In short, the errors are in that case only derived from the covariance  
> matrix and chi-squared. In addition, the manual says: "If you need to  
> work with the covariance matrix, and in general for any serious  
> statistical analysis of a fit, you must define errors for your data  
> points!"
>
> Best regards
>
> Kurt Sutter
>
>
>
> On 3. Aug 2010, at 17:14, kaasis wrote:
>
>> Hello all,
>>
>> I am new to profit, and I would like to know how the errors on fit  
>> parameters are calculated. It does not seem to need a Delta_x ? Is it  
>> only derived from the covariance matrix ? I did not find any  
>> indication in the help files or in previous messages on this list.
>>
>> Best regards,
>> Saskia
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>
>
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