[Ifeffit] statistics

[Stefano Ciurli]

Hello folks,

I am sure this is an easy question answered many times, but I need 
some refresh:

When it comes down to compare fits using different models, which is 
the relevant parameter? Chi square (and reduced) or R-factor? I have 
fits with smaller chi square and larger Rfactor and viceversa...

Is it possible that a rationale would be that when the models to 
compare have the same number of atoms these parameters go in 
parallel? And that when the number of atoms is different one must 
rely more on chi square rather than R-factor (or viceversa)?

Oh well.
Stefano
-- 
____________________________________________

Stefano Ciurli
Professor of Chemistry
Department of Agro-Environmental Science and Technology
University of Bologna
Viale Giuseppe Fanin, 40
I-40127 Bologna
Italy
Phone:	+39-051-209-6204
Fax: 	+39-051-209-6203

"Fatti non foste a viver come bruti,
ma per seguir virtute e canoscenza"
Dante Alighieri - Inferno - Canto XXVI

"Ihr seid bestimmt, nicht Tieren gleich zu leben,
Nein, Tugend zu erringen und Erkenntnis"
"Ye were not form'd to live the life of brutes,
But virtue to pursue and knowledge high"