Data Item _refine.overall_SU_ML


Item name
Category name
Attribute name
Required in PDB entries
Used in current PDB entries
Yes, in about 60.7 % of entries

Item Description

The overall standard uncertainty (estimated standard deviation) of the positional parameters based on a maximum likelihood residual. The overall standard uncertainty (sigmaX)2 gives an idea of the uncertainty in the position of averagely defined atoms (atoms with B values equal to average B value) 3 Na (sigmaX)2 = --------------------------------------------------------- 8 pi2 sumi {[1/Sigma - (Eo)2 (1-m2)](SUM_AS)s2} Na = number of atoms Eo = normalized structure factors m = figure of merit of phases of reflections included in the summation s = reciprocal-space vector SUM_AS = (sigmaA)2/Sigma2 Sigma = (sigma{E;exp})2 + epsilon [1-(sigmaA)2] sigma{E;exp} = experimental uncertainties of normalized structure factors sigmaA = <cos 2 pi s deltax> SQRT(SigmaP/SigmaN) estimated using maximum likelihood SigmaP = sum{atoms in model} f2 SigmaN = sum{atoms in crystal} f2 f = atom form factor deltax = expected error epsilon = multiplicity of diffracting plane summation is over all reflections included in refinement Ref: (sigma_A estimation) "Refinement of macromolecular structures by the maximum-likelihood method", Murshudov, G. N., Vagin, A. A. & Dodson, E. J. (1997). Acta Cryst. D53, 240-255. (SU ML estimation) Murshudov, G. N. & Dodson, E. J. (1997). Simplified error estimation a la Cruickshank in macromolecular crystallography. CCP4 Newsletter on Protein Crystallography, No. 33, January 1997, pp. 31-39.

Additional Descriptive Information for Depositors

 The overall standard uncertainty (estimated standard deviation) of the displacement parameters based on a maximum likelihood residual.

Data Type

Data type code
Data type detail
float item types are the subset of numbers that are the floating numbers.
Primitive data type code
Regular expression

Advisory Boundary Conditions

Minimum Value Maximum Value
0 0.6