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Eleanor, Can you elaborate on your statement about the expected value of (Rfree-R) for moderate/low resolution structures? Thanks. Jack John J. Tanner Associate Professor of Chemistry and Biochemistry University of Missouri-Columbia 125 Chemistry Building 601 S. College Ave. Columbia, MO 65211 http://www.chem.missouri.edu/TannerGroup/tanner.html -- > From: Eleanor Dodson <[EMAIL PROTECTED]> > Reply-To: <[EMAIL PROTECTED]> > Date: Wed, 05 Jul 2006 14:18:39 +0100 > To: Li Sheng <[EMAIL PROTECTED]> > Cc: ccp4bb <[email protected]> > Subject: Re: [ccp4bb]: > > I dont think that sort of Rfactor/Rfree difference at 2.7A is very > surprising.. > > However there may be a scaling problem. If using refmac look at the > Rfactor and <F> analysis. > > Is the <Fcalc> higher or lower than the <Fobs> in general? Or is there > an indication that the distribution of <Fobs> is skewed in some way? > With such limitd data the scaling can easily be distorted. You might do > better to use SCALE SIMPLE if you are using SCALE BULK or vice versa. > Eleanor > > > Li Sheng wrote: > >> *** For details on how to be removed from this list visit the *** >> *** CCP4 home page http://www.ccp4.ac.uk *** >> >> >> Hi, dear all, >> >> Please do me a favour. I ever collected a data set of 2.7A. The space group >> is C2. The model fit the 2fofc map and the omit map very well. The R factor >> is 0.26 now but R free is 0.37 and can not be minished. What kind of error >> can cause such a gap between R factor and R free? >> Thanks in advance. >> >> >> >> >> >> Sincerely yours, >> Li >> 2006.06.07 >> >> >> >> >> >
