Have a look at Rfree and the Rfree Ratio. I. Derivation of Expected Values of Cross-Validation Residuals Used in Macromolecular Least-Squares Refinement. Tickle IJ, Laskowski RA and Moss DS Acta Cryst. (1998). D54, 547-557 http://dx.doi.org/10.1107/S0907444997013875
and Rfree and the Rfree ratio. II. Calculation of the expected values and variances of cross-validation statistics in macromolecular least-squares refinement. Tickle IJ, Laskowski RA and Moss DS Acta Cryst. (2000). D56, 442-450 http://dx.doi.org/10.1107/S0907444999016868 Regards, Mitch -----Original Message----- From: CCP4 bulletin board [mailto:[EMAIL PROTECTED] On Behalf Of Kay Diederichs Sent: Thursday, November 15, 2007 8:42 AM To: [email protected] Subject: [ccp4bb] difference of R_work and R_free as a function of resolution Dear crystallographers, today I explained to a student that I believe that the difference of R_work and R_free should decrease as a function of resolution, because at high resolution there is less danger of overfitting, whereas at low resolution one is always overfitting to some extent. I'd say this should be true at least in absolute terms, but probably even in relative terms: for example, for a 1.5A structure I'd expect R_work/R_free= 14%/16%, whereas at 3A I'd expect 28%/35%. I believe that I saw plots (maybe in a link given in a posting on CCP4BB) obtained for structures from the PDB, which confirmed this hypothesis. But I've been googling and searching through postings now for quite some while, and cannot seem to find anything to that effect. Does anybody have a pointer to an analysis of this effect? thanks, Kay P.S. Would be good to put this into the CCP4 Wiki article on R-factors -- Kay Diederichs http://strucbio.biologie.uni-konstanz.de email: [EMAIL PROTECTED] Tel +49 7531 88 4049 Fax 3183 Fachbereich Biologie, Universität Konstanz, Box M647, D-78457 Konstanz
