Hi David, On Fri, 18 Dec 2020 11:53:08 +0000, David Waterman <dgwater...@gmail.com> wrote:
>Hi folks > >The paper "Substructure solution with SHELXD ><https://journals.iucr.org/d/issues/2002/10/02/gr2280/index.html>" >(Schneider & Sheldrick, 2002) describes how > >data can be truncated at the resolution at which [ΔF to its estimated >> standard deviation as a function of the resolution] drops to below about 1.3 > > >Is this referring to the quantity <|ΔF|>/<σ(ΔF)> calculated in resolution >shells, or the quantity <|ΔF|/σ(ΔF)> ? the latter the only scaling program that I know of that calculates ratios of averages is SCALEPACK; the others calculate averages of ratios. > >This entry ><https://strucbio.biologie.uni-konstanz.de/ccp4wiki/index.php?title=SHELX_C/D/E#Resolution_cutoff_.28SHEL.29> >on the ccp4wiki gives a cutoff > >where the mean value of |ΔF|/σ(ΔF) falls below about 1.2 (a value of 0.8 >> would indicate pure noise) > > >this version sounds to me like <|ΔF|/σ(ΔF)> yes > >which is the "better" metric, and what do people mean when they say >DANO/SIGDANO? What is the justification for the 1.3 (or 1.2) value? I don't know the justification; maybe just experience? Surely the higher the better. I've seen George Sheldrick deriving the value of ~0.8 when there is _no_ anom signal but I forgot the details, sorry ... best wishes, Kay > >Thanks! >-- David > >######################################################################## > >To unsubscribe from the CCP4BB list, click the following link: >https://www.jiscmail.ac.uk/cgi-bin/WA-JISC.exe?SUBED1=CCP4BB&A=1 > >This message was issued to members of www.jiscmail.ac.uk/CCP4BB, a mailing >list hosted by www.jiscmail.ac.uk, terms & conditions are available at >https://www.jiscmail.ac.uk/policyandsecurity/ > ######################################################################## To unsubscribe from the CCP4BB list, click the following link: https://www.jiscmail.ac.uk/cgi-bin/WA-JISC.exe?SUBED1=CCP4BB&A=1 This message was issued to members of www.jiscmail.ac.uk/CCP4BB, a mailing list hosted by www.jiscmail.ac.uk, terms & conditions are available at https://www.jiscmail.ac.uk/policyandsecurity/
