[phenixbb] Maps Bias

Pavel Afonine pafonine at lbl.gov
Wed Sep 21 16:14:18 PDT 2011


Hi Yuri,

virtually any map computed using model phases is model biased.

2mFo-DFc map computed with m and D estimated using "free" reflections is 
less model biased than (Fobs, PHIcalc). See R.Read (1986).

Iterative-build OMIT maps seem to be the least model biased:

*Iterative-build OMIT maps: map improvement by iterative model building 
and refinement without model bias.*T. C. Terwilliger, R. W. 
Grosse-Kunstleve, P. V. Afonine, N. W. Moriarty, P. D. Adams, R. J. 
Read, P. H. Zwart and L.-W. Hung/Acta Cryst./*D64*, 515-524 (2008) 
<http://www.iucr.org/cgi-bin/paper?wd5088>

Pavel


On 9/21/11 4:07 PM, Yuri wrote:
> I was having a discussion with a friend about maps and model bias.
> Is the Fobs/PHImodel more biased than 2FOFCWT/PHI2FOFCWt?
> What about an omit region of these two?
> Thanks for any opinion on this
>

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