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)

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