title: Rearrangement of Cruickshank's formulae for the diffraction-component precision index.
abstract: The formulae for the diffraction-component precision index introduced by Cruickshank [(1999), Acta Cryst. D55, 583-601] are simplified using two approximations. A rearranged formula for the precision index is presented which can readily be calculated from experimental data. It is shown that the precision varies as (resolution)(5/2) if R and completeness are maintained. It varies as (completeness of intensity measurement)(-5/6) and its dependence on the inclusion of solvent atoms is discussed.
authors.affiliation: Biophysics Group, Imperial College of Science, Technology and Medicine, London SW7 2AZ, England. d.blow@ic.ac.uk
authors.forename: D M
authors.initials: DM
authors.lastname: Blow
mesh_terms: D018360:Crystallography, X-Ray / Q000379:methods*; D030562:Databases, Protein; D008433:Mathematics; D008970:Molecular Weight; D011487:Protein Conformation; D011506:Proteins / Q000737:chemistry*; D012997:Solvents / Q000737:chemistry
chemical_list: D011506:Proteins; D012997:Solvents