When will we finally jettison Rsym/Rcryst/Rmerge? 1. Perhaps software developers should either not even calculate the number, or hide it somewhere obscure, and of course replacing it with a better R flavor?
2. Maybe reviewers should insist on other R's (Rpim etc) instead of Rmerge? JPK PS is this as quixotic as chucking the QWERTY keyboard, or using Esperanto? I don't think so! On Thu, Mar 3, 2011 at 11:07 AM, Simon Phillips <s.e.v.phill...@leeds.ac.uk> wrote: > > I take the point about a tendency in those days to apply sigma cutoffs to > get lower R values, which were erroneously expected to indicate better > structures. I wonder how many of us remember this paper by Arnberg et al > (1979) Acta Cryst A35, 497-499, where it is shown for (small molecule) > structures that had been refined with only reflections I>3*sigma(I) that the > models were degraded by leaving out weak data (although the R factors looked > better of course). > > Arnberg et al took published structures and showed the refined models got > better when the weak data were included. The best bit, I think, was when > they went on to demonstrate successful refinement of a structure using ONLY > the weak data where I<3*sigma(I) and ignoring all the strong ones. This > shows, as was alluded to earlier in the discussion, that a weak reflection > puts a powerful constraint on a refinement, especially if there are other > stronger reflections in the same resolution range. > > --------------------------------------------------------------------------- > | Simon E.V. Phillips | > --------------------------------------------------------------------------- > | Director, Research Complex at Harwell (RCaH) | > | Rutherford Appleton Laboratory | > | Harwell Science and Innovation Campus | > | Didcot | > | Oxon OX11 0FA | > | United Kingdom | > | Email: simon.phill...@rc-harwell.ac.uk | > | Tel: +44 (0)1235 567701 | > | +44 (0)1235 567700 (sec) | > | +44 (0)7884 436011 (mobile) | > | www.rc-harwell.ac.uk | > --------------------------------------------------------------------------- > | Astbury Centre for Structural Molecular Biology | > | Institute of Molecular and Cellular Biology | > | University of LEEDS | > | LEEDS LS2 9JT | > | United Kingdom | > | Email: s.e.v.phill...@leeds.ac.uk | > | Tel: +44 (0)113 343 3027 | > | WWW: http://www.astbury.leeds.ac.uk/People/staffpage.php?StaffID=SEVP | > --------------------------------------------------------------------------- -- ******************************************* Jacob Pearson Keller Northwestern University Medical Scientist Training Program cel: 773.608.9185 email: j-kell...@northwestern.edu *******************************************
