[Ifeffit] Question about transform windows and statistical parameters

Brandon Reese bjreese at gmail.com
Wed May 11 14:46:59 CDT 2011

Hello everybody,

I am working on fitting some EXAFS of amorphous materials and have noticed
an odd (in my mind) behavior when changing transform windows.  I settled on
a fit using all three k-weights and the Hanning transform window obtaining
statistical parameters of R=0.0018 and chi_R=361.  I decided to change the
transform window to a Kaiser-Bessel to see what would happen.  The refined
parameters came out more or less the same, well within the error bars, with
the Hanning windows having slightly smaller error bars.  But my statistical
parameters changed significantly to R=0.0022 and chi_R=89.354.  It seems
that this large change may be related to why we can't use the chi_R
parameter to compare fits over different k-ranges, but I am not sure about
that.  Have other people seen this?  I would guess it means that when
looking for trends in different data sets, it is more important to be
consistent, rather than which specific window type is used.

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://millenia.cars.aps.anl.gov/pipermail/ifeffit/attachments/20110511/bc284172/attachment.html>

More information about the Ifeffit mailing list