Dear Mark et al., In small molecule crystallography one always refines against ALL data up to a specified resolution, usually 0.83A or better. Failure to do this generates a category A CheckCIF alert! However one is expected to give both the R-value for all data and a R-value for I < 2sigma(I). This is actually quite useful, if the first of these is appreciably larger than the second - say 10% and 3% - then the data must be weak.
Best wishes, George On 11/14/2013 12:27 PM, Mark J van Raaij wrote: > It used to be common to only include reflections for which I > x sigma(I) in > refinement, with x often being 3. > However, nowadays this is not considered good practise, as reflections with > small Is are likely to have I < 3 sigma(I), but are also important for > refinement. > > In small molecule crystallography I think it is still common to have a sigma > criterion. > > if, in this respect, you have used default settings in data reduction and > refinement, you should select "none" or "n.a." in the deposition process. > > Mark J van Raaij > Lab 20B > Dpto de Estructura de Macromoleculas > Centro Nacional de Biotecnologia - CSIC > c/Darwin 3 > E-28049 Madrid, Spain > tel. (+34) 91 585 4616 > http://www.cnb.csic.es/~mjvanraaij > > > > > > On 14 Nov 2013, at 12:06, Faisal Tarique wrote: > >> Dear all >> >> I request you to please explain the "Observed criterion sigma" value >> required during pdb deposition. Does it depends on the methods of data >> integration and scaling ? if yes then what are the values for the data >> processed through scalepack2mtz (HKL2000) and scala (mosflm).. >> >> -- >> Regards >> >> Faisal >> School of Life Sciences >> JNU > -- Prof. George M. Sheldrick FRS Dept. Structural Chemistry, University of Goettingen, Tammannstr. 4, D37077 Goettingen, Germany Tel. +49-551-39-33021 or -33068 Fax. +49-551-39-22582
