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
<[log in to unmask]> 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.
>
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Jacob Pearson Keller
Northwestern University
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