Jon, do you call it a difference (7.6% versus 7.7%) ? I wouldn't even for a good bunch of Fobs from a good inorganic single crystal ... Well, maybe this a matter of taste, maybe this no difference at all. I wonder if Rf has any statistical meaning, it could work like an indicator of convergence - a rough one, BTW. Best, Lubo
On Fri, 21 Jan 2005, Jon Wright wrote: > Hello everyone, > > Has anyone else noticed that sometimes when comparing two models Rwp is > better for one and R(F^2) is better for the other? The case I am looking > at is spacegroups P3 versus P-3, with the non-centrosymmetric structure > having more degrees of freedom and therefore very slightly better Rwp > (7.6% versus 7.7%). I don't understand why it has a much worse R(F^2), > 8.5% versus 7.3%. These numbers are coming from GSAS, which gives the > same number of F_obs reflections for each of the two fits. I haven't > looked into the details much, but shouldn't the two statistics be better > correlated than that? > > Thanks for any hints! > > Jon > >
