Dear Gerard, I disagree in two points with what you write:
On Mon, 10 Jun 2024 19:15:43 +0100, Gerard Bricogne <g...@globalphasing.com> wrote: ... > Much worse, in fact: that quantity (I_avg/sigI_avg) makes no sense >whatsoever in statistical terms. It must be a relic of a quantity that may >have seemed like a good idea to someone at some stage, and has since been >dutifully carried along forever after, and "gold-plated" so as to still be >present in the latest revision of the mmCIF dictionary. The quantity I_avg/sigI_avg (= <I>/<sigI>) makes as much sense in statistical terms as does Mn(I/sigI) (=<I/sigI>). As I said, numerically they are often similar (within 20% or so), in particular at high resolution. IIRC, SCALEPACK (from the HKL package) prints out <I>/<sigI> (or used to print it out; maybe this has changed). So there might be a reference to the usage of "I_avg/sigI_avg". > > Perhaps you could request a reference to the publication in which this >quantity was proposed as a validation criterion and its acceptable limits >were derived :-) . > > This being said, if it is indeed the case that the average value of >your intensities is smaller than the average of their standard deviations, >there is definitely something wrong somewhere. Perhaps a confusion between >columns containing values pertaining to intensities vs. amplitudes? There is nothing wrong if "the average value of your intensities is smaller than the average of their standard deviations", if the warning that Aline reports refers to the outer shell. If it refers to the whole dataset, yes then there's something wrong. Best wishes, Kay ######################################################################## 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/
