Data Item _refine.overall_SU_R_Cruickshank_DPI
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General 
- Item name
- _refine.overall_SU_R_Cruickshank_DPI
- Category name
- refine
- Attribute name
- overall_SU_R_Cruickshank_DPI
- Required in PDB entries
- no
- Used in current PDB entries
- Yes, in about 4.2 % of entries
Item Description
The overall standard uncertainty (estimated standard deviation)
of the displacement parameters based on the crystallographic
R value, expressed in a formalism known as the dispersion
precision indicator (DPI).
The overall standard uncertainty (sigmaB) gives an idea
of the uncertainty in the B values of averagely defined
atoms (atoms with B values equal to the average B value).
Na
(sigmaB)2 = 0.65 ---------- (Rvalue)2 (Dmin)2 C-2/3
(No-Np)
Na = number of atoms included in refinement
No = number of observations
Np = number of parameters refined
Rvalue = conventional crystallographic R value
Dmin = maximum resolution
C = completeness of data
Ref: Cruickshank, D. W. J. (1999). Acta Cryst. D55, 583-601.
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.
http://www.ccp4.ac.uk/newsletters/newsletter33/murshudov.html
Data Type 
- Data type code
- float
- Data type detail
- float item types are the subset of numbers that are the floating numbers.
- Primitive data type code
- numb
- Regular expression
- -?(([0-9]+)[.]?|([0-9]*[.][0-9]+))([(][0-9]+[)])?([eE][+-]?[0-9]+)?