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 [log in to unmask] 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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