I was [too] obliquely alluding to this thread... http://www.mail-archive.com/ccp4bb@jiscmail.ac.uk/msg27056.html
JPK On Wed, Jul 18, 2012 at 12:32 PM, Edwin Pozharski <epozh...@umaryland.edu>wrote: > http://www.ysbl.york.ac.uk/ccp4bb/2001/msg00383.html > > > > > Rsym...what's that? > > > > JPK > > > > On Wed, Jul 18, 2012 at 9:12 AM, Edwin Pozharski > > <epozh...@umaryland.edu>wrote: > > > >> As has been shown recently (and discussed on this board), Rsym is not > >> the > >> best measure of data quality (if any measure at all): > >> > >> http://www.sciencemag.org/content/336/6084/1030.abstract > >> > >> > >> > >> > narayan viswam wrote: > >> >> Hello CCP4ers, > >> >> In my data, the highest reolution shell 2.8-3.0 A has I/sigmaI 2.5 & > >> >> Rsym 224.3 % > >> >> for multiplicity 7.8 and completeness 98.2 %. I solved the structure > >> by > >> >> MAD & refined it > >> >> to Rfree 27.3 %. Ths crystal belongs to P622 space group and it is > >> not > >> >> twinned. The water > >> >> content is 68%. I loweredthe multiplicity to 4.1 by excluding few > >> >> images but still the > >> >> Rsym is > 200 % and I/sigmaI > 2.0. My rudimentary crystallography > >> >> knowledge makes me > >> >> believe it's quite Ok to use data upto 2.8 A and report the > >> statistics. > >> >> Could I request > >> >> people's views. Thanks very much. > >> >> Narayan > >> > > >> > After refinement, what is R-free in the last shell? If it is > >> significantly > >> > better > >> > than random, say around .4 or less, that could be taken as evidence > >> that > >> > there > >> > is data in the last shell. > >> > Also check the error model- Rsym >2 sort of implies the error is > >> greater > >> > than > >> > the signal, so I/sigI 2 seems surprising. > >> > eab > >> > > >> > >> > >> -- > >> Edwin Pozharski, PhD > >> University of Maryland, Baltimore > > > > > > > > > > -- > > ******************************************* > > Jacob Pearson Keller > > Northwestern University > > Medical Scientist Training Program > > email: j-kell...@northwestern.edu > > ******************************************* > > > > > -- > Edwin Pozharski, PhD > University of Maryland, Baltimore > -- ******************************************* Jacob Pearson Keller Northwestern University Medical Scientist Training Program email: j-kell...@northwestern.edu *******************************************
