[phenixbb] difference in estimated error between phenix and refmac
Pavel Afonine
pafonine at lbl.gov
Thu Aug 12 11:49:20 PDT 2010
Hi Ling,
I have no idea what the error estimate based on R means. In
phenix.refine the ML based coordinate error estimate is done as
described in formula #19 in
/Acta Cryst./ (2002). A*58*, 270-282
with the ML parameters determined as described here:
Acta Cryst. (1995). A51, 880-887.
and
J. Appl. Cryst. (1996). 29, 741-744.
This number is sensitive to many (irrelevant) thins such as bulk-solvent
model, etc.. So I wouldn't take it too literally. Model to map fit, map
quality, local and global, geometry stats and Rfactors are all much more
useful model quality characteristics than this number.
Pavel.
On 8/12/10 10:04 AM, Ling Qin wrote:
> Dear Colleagues,
>
> I am refining a 2.15 A structure that was previously refined with
> refmac by someone else. Without changing anything in the
> refmac-refined model and using all the default phenix.refine settings,
> I am getting pretty much the same R and Rfree (from 19.3%/21.7% to
> 18.9%/21.8%), with an ML estimated error of 0.22 A. In the
> refmac-refined pdb file, the estimated error is much lower: 0.16
> (based on R), 0.144 (based on Rfree), and 0.096 (based on ML). I am
> using phenix.refine version 1.6_289, but also tried 1.5_2 with the
> same result. Is there an underlying reason for this difference? Thank
> you very much for your insightful opinions in advance.
>
> Cheers,
>
> Ling
>
>
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