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! ;-) B -- Bruce Ravel ----------------------------------- ravel@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/