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Another criterion for cutoff, also requiring the structure to be solved, is the agreement between data and structure, e.g. Rfree or CCfree. I think it is very unlikely that you could get Rfree =.2493 in a shell which contains only noise. So I would suggest doing paired refinement to 2.2 and 2.1 A (if the data is available). On 07/01/2015 07:15 PM, Eric Karg wrote: > Hi all, > > I have a dataset processed in XDS to 2.3 A (based on CC1/2). I'm trying to do "paired refinement" to determine the optimal resolution cutoff. Here is what I get at different resolutions set in Phenix: > > Final Rfree/Rwork: > 2.7—> 0.2498/0.2027 > 2.6—> 0.2519/0.2009 > 2.5—> 0.2567/0.2025 > 2.4 —> 0.2481/0.2042 > 2.3 —> 0.2493/0.2075 > > The geometry of all output structures are similar. > > 1. What is the high resolution cutoff based on these data? I know that Rfree/Rwork at different resolution should not be compared, but is there a simple way to do the test as described in the K&D 2012 Science paper using Phenix GUI? > > 2. For refining a structure at a lower resolution (lower than the initial dataset), do I simply set the resolution limit in the refinement or I need to reprocess the data starting from the images? Do I need to do anything with Rfree flags? Based on the discussions on this forum I know I should deposit the highest resolution dataset but my question is about the mtz file which will be used for refinement. > > Thank you very much for your help! >