Le 24/01/12 21:18, Dale Tronrud a écrit : > On 01/24/12 11:52, Miguel Ortiz Lombardia wrote: >> El 24/01/12 18:56, Greg Costakes escribió: >>> Whoops, I misspoke... I meant Rsym and Rmerge increase with higher >>> redundancies. >>> >> >> But then suppose that one merges data from a crystal that is degrading >> while exposed, sp the data gets degraded. This is not at all unusual. In >> the absence of a deep understanding of refinement, intuition suggests >> that degraded data should produce degraded models. If Rwork and Rfree >> are measuring anything useful they should go up redundancy in those >> not-so-unusual cases. Or intuition is misguiding me again. >> > > Yes, if one has a poorer quality data set one expects the Rw and Rf to > be higher, but this is not necessarily a correlation to high redundancy. > Surely if you have high redundancy and know the crystal is decaying you > have to flexibility to not use the decayed data in the merge. I would > expect that decayed data would only be merged with the early data if > the redundancy was so low that you had to just to get a full data set. > > Dale Tronrud >
I agree. I would also expect so... unless the user simply runs the data reduction software and does not check the log files to see, among other important issues, at what point the data starts degrading due to a decaying crystal. If the software is clever enough to decide by itself, it will be all right or sort of, which is, I suppose, a good point for automation. Unfortunately, there are many users of black boxes, which is, I presume, a danger of automation. My answer was kind of a caveat for such type of users. -- Miguel Architecture et Fonction des Macromolécules Biologiques (UMR7257) CNRS, Aix-Marseille Université Case 932, 163 Avenue de Luminy, 13288 Marseille cedex 9, France Tel: +33(0) 491 82 55 93 Fax: +33(0) 491 26 67 20 mailto:miguel.ortiz-lombar...@afmb.univ-mrs.fr http://www.afmb.univ-mrs.fr/Miguel-Ortiz-Lombardia
