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
