[Ifeffit] Reporting the fitting data (uncertainty associated with N)
pshejwalkar2004 at gmail.com
Wed Nov 5 01:46:45 CST 2014
Thank you very much for the quick and illustrative solution.
On Tue, Nov 4, 2014 at 9:24 PM, Matt Newville <newville at cars.uchicago.edu>
> The amplitude parameter is N*S02, so that S02 and N are completely
> correlated. If you
> set N = 2
> guess S02 = 0.8
> and the fit returns
> S02 = 0.75 +/- 0.05
> Then the correct interpretation is that
> N*S02 = 2*(0.75 +/- 0.05) = 1.5 +/- 0.10
> If you had asserted that S02 = 0.75 and vary N, then you should get
> N = (1.5 +/- 0.10) / 0.75 = 2 +/- 0.13333
> The uncertainty in S02 and N cannot be separated for a single
> spectrum. The most common approach is to assert that S02 depends on
> X-ray energy resolution (beamline setup) and absorbing atom, and use a
> constant value for S02 derived from spectra from samples with a
> well-known coordination environment (a "standard").
> On Tue, Nov 4, 2014 at 3:22 AM, pushkar shejwalkar
> <pshejwalkar2004 at gmail.com> wrote:
> > Dear All,
> > I have seen and also been told by few professors that when you
> > report the fitting you must report the uncertainty associated with the
> > measurement as evaluated by the program used for the fitting.
> > Now, When I do the fitting I typically get the +/- values for E0, delR,
> > and SO2. However, the N value we always put either 1,2 or such whole
> > integers. Is there any way to find out the uncertainty associated with
> > coordination number (N used in XAFS equation)?
> > If so how to find such uncertainty? can we see this in the log file
> > generated after the fitting is over?
> > Thank you very much for the help
> > Best Regards,
> > Pushkar Shejwalkar.
> > Post-doctoral -Researcher,JSPS Fellow
> > Hokkaido University,
> > Sapporo,
> > Japan
> > _______________________________________________
> > Ifeffit mailing list
> > Ifeffit at millenia.cars.aps.anl.gov
> > http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit
> Ifeffit mailing list
> Ifeffit at millenia.cars.aps.anl.gov
Post-doctoral -Researcher,JSPS Fellow
-------------- next part --------------
An HTML attachment was scrubbed...
More information about the Ifeffit