[Ifeffit] Different R-factor values

[Jason Gaudet]

Hi Chris,

Might be helpful also to link to the archived thread you're talking about.

http://millenia.cars.aps.anl.gov/pipermail/ifeffit/2006-June/007048.html

Bruce might have to correct me on this, but if I remember right there were
individual-data-set R-factor and chi-square calculations at some point,
which come not from IFEFFIT but from Bruce's own post-fit calculations, and
these eventually were found to be pretty buggy and were dropped.

I don't understand what "the average over the k weights" R factor is;
analyzing the same data set with multiple k weights (which is pretty
typical) still means a single fit result and a single statistical output in
IFEFFIT, as far back as I can remember, anyhow.  The discussion about
multiple R-factors is for when you're simultaneously fitting multiple data
sets (i.e. trying to fit a couple different data sets to some shared or
partially shared set of guess variables).

I think the overall residuals and chi-square are the more statistically
meaningful values, as they are actually calculated by the same algorithm
used to determine the guess variables - they're the quantities IFEFFIT is
attempting to reduce.  I don't believe I've reported the per-data-set
residuals in my final results, as I only treated it as an internal check
for myself.  (It would be nice to have again, though...)

-Jason

On Thu, Jan 24, 2013 at 10:12 AM, Christopher Patridge <patridge at buffalo.edu
> wrote:

>  I am reviewing some older analysis projects from artemis and just wanted
> to know which R-factor more accurately describes the misfit?  I suspect the
> average over the k weights values since this was adopted in Demeter?
>
> Thanks,
>
> Chris Patridge
>
> --
> ********************************
> Christopher J. Patridge, PhD
> NRC Post Doctoral Research Associate
> Naval Research Laboratory
> Washington, DC 20375
> Cell: 315-529-0501
>
>
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