Re: Goodness of fit criterion

2008-06-03 Thread Jonathan Wright
There can be some value in comparing S values for different models with the same data (eg ranking at least). A value much less than 1 (eg 1E-3) indicates that you lost an "esd" column (or scaling factor) somewhere in your data processing, and you should really try to find it again. Having S>>2

Re: Goodness of fit criterion

2008-06-02 Thread Lubomir Smrcok
Hi, S is, strictly speaking a valid criterion only under special conditions which are not fulfilled in "Rietveld". My advice is to forget about the value of S and think of physics, i.e. bond distances, angles, occupancies and in favorite cases, also of displacement parameters. Lubo On Tue, 3