Hello, I am trying to find out the reason for a large R-free difference that I am getting between phenix.refine and phenix.model_vs_data: phenix.refine R-work/R-free 0.1702/0.1974 phenix.model_vs_data R-work/R-free 0.1728/0.1795 Initial refinement was using the intensities in an XDS_ASCII.HKL dataset, followed by a few refinement cycles against the same dataset, but using amplitudes calculated in Aimless, with the ‘skip scaling just merge’ option and keeping the FreeR reflections. When I checked R-free values for the last refinement run before the conversion, there was no large discrepancy: phenix.refine R-work/R-free 0.1720/0.2086 phenix.model_vs_data R-work/R-free 0.1715/0.2080 Can anyone please advise? Apart from this, refinement went well - both the 1.9A map and the model look fine. Thanks for the help & happy New Year, Luca Luca Pellegrini, PhD Department of Biochemistry University of Cambridge 80 Tennis Court Road Cambridge CB2 1GA UK Email: [email protected] Phone: 0044-1223-760469