Am Dienstag, den 23.03.2010, 08:56 +0000 schrieb Christina Drathen: > Dear all, > > I am working on a refinement of synchrotron-X-ray powder data; the fit > is ok (though certainly not perfect) but I ended up with a confusingly > small reduced chi^2: > Rp = 23.4% > wRp = 16.9% > F^2 = 18.6% > chi^2 = 0.755 > (1733 observations, 15 variables). > > I would be very grateful for any suggestions on how to solve this problem. > > Regards, > Christina >
>From a statistical point of view, you have no problem. Your chi^2 is of degree k=1718, which gives a variance of sqrt(2k)=59. In following, you should expected Rwp=18.6(0.64). In following, your Rwp is inbetween the 3 sigma range of F^2. Of course, assuming no systematic/model error is somewhat optimistic... Regards Joerg
