ARE: [Ifeffit] Re: Ifeffit Digest, Vol 5, Issue 1
ravel at phys.washington.edu
Mon Jul 7 12:11:08 CDT 2003
On Monday 07 July 2003 12:45 pm, Matt Newville wrote:
> Anyway, I think using the 'epsilon_k' that chi_noise() estimates as
> the noise in chi(k) is a fine way to do a weighted averages of data.
> It's not perfect, but neither is anything else.
Exactly right! As Matt explained, there are reasons to believe that
the measurement uncertainty is dominated by things that Parsival's
theorem doesn't address and that measuring those problems is hard.
As Matt said, weighting by 1/chi_noise() is OK. As Scott said,
weighting uniformly is OK. Those are two choices are the most OK I
can think of, so Athena will let you choose between them.
While I am of the chorus of people agreeing with Grant that mu is not
equal to <If>/<I0>, I can see no reason why Athena should actively
prevent the user from looking at <If> or <I0>, if that is what he
wants to do. The *current* version of Athena prevents this, but
that's a bug not a feature! ;-)
Bruce Ravel ----------------------------------- ravel at phys.washington.edu
Code 6134, Building 3, Room 222
Naval Research Laboratory phone: (1) 202 767 5947
Washington DC 20375, USA fax: (1) 202 767 1697
NRL Synchrotron Radiation Consortium (NRL-SRC)
Beamlines X11a, X11b, X23b, X24c, U4b
National Synchrotron Light Source
Brookhaven National Laboratory, Upton, NY 11973
My homepage: http://feff.phys.washington.edu/~ravel
EXAFS software: http://feff.phys.washington.edu/~ravel/software/exafs/
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