[ccp4bb]: Reporting diffraction data quality

[Florian Schmitzberger]

Dear All, I would have a question about reporting diffraction data quality indicators (for pdb-submission and publication) for data processed with XDS/XSCALE. XSCALE(.LP) lists data quality indicators such as completeness, mean <I>/sigma<I>, R-meas etc. for several signal/noise cutoffs descending to negative values for the latter (up to -3.0). I was wondering whether it makes more sense to report data quality for data with a signal/noise > 0 (or indeed 1) rather than report the data quality for (all) data with a signal/noise >-3.0. Whereas I imagine for error estimates and standard deviation calculations (in ML-based refinement) including the quality of the negative intensity reflections (signal/noise >-3.0) is still meaningful to know, these reflections probably did not contribute significantly to the diffraction, calculation of the electron density, and the final model.  I am asking this since I observe the following difference (I suppose because of the altered sd estimates) between the tables for the 0.0 (Rmeas=94% (flame on, I am aware) and  I/sigmaI= 1.83) and  -3.0 (and  Rmeas=106.4%,  I/sigmaI= 1.51) signal/noise cutoff.  I am aware this question is of a rather cosmetic nature and the data will of course be the same (but reporting may have slightly different effects on referees, I could imagine). Thank you very much in advance for any comments! Regards, Florian -------------------------------------------- Florian Schmitzberger Medical Biochemistry and Biophysics Karolinska Institute Scheeles vaeg 2 SE-171 77 Stockholm, Sweden Tel: +46-8-524-86875