[Ifeffit] Meaning of linear combination fit reports
Jens Kruse
4.meinereiner at gmx.de
Mon Aug 18 09:12:08 CDT 2014
Hi everyone,
I doing LCF on my XANES data. I wonder if someone can tell me the
meaning of the values in parentheses following the weight value in the
Fit results window?. I looked into the respective document section of
the Manuel but could not find the answer, yet.
I am asking because I did a Fitting with over 20 standards (STD) to find
all combination of max 4 standards which describe my unknown sample
spectra. This results in a lot of combination with similar
chi-square(reduced) and R-values. I know a relative changes between
these values are more probably meaningful than absolute values.
A lot of the possible combinations provided by after the fit yieled
combinations with at lest on STD having a weight of 0.000. (Fit 1). I
thought that this would mean, that 3 standards are sufficient to
describe the system. However, repeating the fit with only the three
standards with weight > 0.0 yielded a complete different proportions
(Fit 2). How can this be explain and how should I deal with
combinations or standards having a weight of 0.000?
Thanks a lot for your thoughts and suggesting,
Cheers Paul
*Results **Fit 1:*
3: STD3 0.324(0.025)
7: STD7 0.686(0.021)
20: STD2O 0.127(0.016)
27: STD27 0.000(0.036)
vs.
*Results Fit 2:*
3: STD3 0.473(0.019)
7: STD7 0.620(0.023)
20: STD20 0.000(0.030)
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