Dear Charles, I would ignore (high resolution) R-values for justifying the rsolution cut-off. If you are talkig about 100s %, I have published data with Rmeas > 500% in the highest resolution shell.
You are quite save cutting the resolution where I/sigI >= 2.0, by todays knowledge this is actually conservative. Another good criterion would be the combination of CC1/2 = 40% AND I/sigI > 1.0 if you want to extend the resolution a litte. If I understand correctly, this latter combined criterion indicates that the standard deviations are estimate correctly. This is important so that downstream programs work, notably maximum likelyhood based refinement programs like refmac or buster. Best, Tim On 09/04/2014 07:25 PM, CPMAS Chen wrote: > Hi, All CCP4BB Users, > > I have quite some data sets(~15) collected at different beam intensities, > the individual dataset can diffract to ~3.8 A @I/dI=2. If I combine them, > with AIMLESS in CCP4, the resolution can be extended to ~3A@I/dI=2. But, > the Rmerge or Rpim is way high, in 10s or even 100s. Would this high R > simply due to the intensity difference among these datasets? Or simply say, > can I trust/use the combined/merged dataset diffracting to 3A? > > Thanks! > > Charles > -- Dr Tim Gruene Institut fuer anorganische Chemie Tammannstr. 4 D-37077 Goettingen GPG Key ID = A46BEE1A
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