It's important to remember that free-R reflections are not only used to calculate Rfree, but also are used in calculation of m and D scales in 2mFo-DFc and mFo-DFc maps, as well as in likelihood-based refinement targets. The fact is that you need to have a sufficient amount of free-R reflections in each relatively thin resolution bin. Some authors estimate this number as at lest 50 reflections per bin. In Phenix binning is defined such that each sufficiently thin bin gets no less than 150 reflections. Bernhard pointed out about "precision or significance of Rfee". Also, I would add that too few free-R reflections can affect refinement progress (not only robustness of Rfree value) (I've done relevant tests to convince myself more than a decade ago)! Thus I favor having 10% just to be on a safer side.
Pavel On Tue, Jul 10, 2018 at 1:02 AM, 张士军 <21620150150...@stu.xmu.edu.cn> wrote: > Dear all > > I am confusing the choose of free R-flags recently. Rfactor > means calculatted from reflection not used in refinement,so what's big the > difference between different percentage of R-flags,like it's about 5% in ccp4 > -refmac, while it is 10% in phenix-refinement,what' > s the difference between them and how they affect the > Rwork and Rfree values when do refinement. Thanks a lot ! > > best regards > > shijun > > ------------------------------ > > To unsubscribe from the CCP4BB list, click the following link: > https://www.jiscmail.ac.uk/cgi-bin/webadmin?SUBED1=CCP4BB&A=1 > ######################################################################## To unsubscribe from the CCP4BB list, click the following link: https://www.jiscmail.ac.uk/cgi-bin/webadmin?SUBED1=CCP4BB&A=1
