On Tuesday, December 06, 2011 09:13:03 am Jacob Keller wrote:
> Dear Crystallographers,
>
> I hate to broach this subject again due to its wildly controversial
> nature, but I was wondering whether there was any reference which
> systematically analyses resolution cutoffs as a function of I/sig,
> Rmerge, Rmeas, Rpim, etc. I strongly dislike Rmerge/Rcryst for
> determining cutoffs, for obvious reasons--and especially for datasets
> of higher multiplicity--but nevertheless it is a ubiquitously-reported
> statistic, and one therefore has to make an argument against using it.
What is your question, exactly?
I don't follow the logic that because a statistic is reported, one
must therefore argue against it.
> Hopefully this could be done by pointing to a definitive reference--or
> am I stuck with a convention versus the truth? Maybe the ACA or
> similar could make a public anti-Rmerge proclamation about it, to make
> it easier for us?
Acta published at one point a guideline as part of the instructions
to authors, but the state of the art passed it by very soon after.
I suspect that is the inevitable fate of any such broad-brush proclamation.
Ethan
>
> Also, more generally, it seems that the refinement programs are now
> better able to discount lousy high-res data, so why not leave the
> choice to those programs, and just give them all of the data to the
> edge of the detector, especially since our computational and data
> storage capacities are now completely sufficient for that? One could
> then use some other metric for the goodness of the structure, such as
> what bin crosses the Rfree = 40% mark or something.
>
> One could push this even further and, as has been mentioned on this
> list before, just give the refinement program all of the intensities
> of the voxels in the 3D dataset?
>
> Jacob
>
>
--
Ethan A Merritt
Biomolecular Structure Center, K-428 Health Sciences Bldg
University of Washington, Seattle 98195-7742
