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Dear Michael,
Irrespective of possibe statistical arguments, I'd rather cut data at
CC_1/2 >= 70%. Having said that I don't think people have come to a
consensus yet and I am so old-fashioned that I mainly cut my data at
I/sigI >= 2. This is based on one or two test-cases, though where
cutting the data at lower I/sigI values resulted in a noisier map
which I found more difficult to interpret.
If you work with such borderline data, integrate to various cut-offs
and pick the one where you feel most comfortable at building your model.
Best,
Tim
On 06/10/2012 12:41 PM, Michael Roberts wrote:
> Dear Crystallographers,
>
> There have been comprehensive discussions on the use of criteria
> such as Rmerge and I/sigma(I) as criteria to define the resolution
> to which X-ray data is to be used for structure determination.
> However, CC 1/2, the correlation between random half sets of data,
> is increasingly being considered as a better means for evaluating
> the resolution cutoff (Karplus and Diederichs). Is there a
> resolution cutoff that can be considered as a acceptable standard,
> say CC 1/2 = 0.5, or does this prompt the counter-question 'how
> long is a piece of string?' in which case resolution values are to
> be quoted at CC 1/2 values of 0.2, 0.3, 0.5, 1, etc?
>
> Best wishes,
>
> Michael
>
> Michael Roberts Crysalin Limited Cherwell Innovation Centre 77
> Heyford Park Upper Hey ford Oxfordshire OX25 5HD
>
>
>
- --
Dr Tim Gruene
Institut fuer anorganische Chemie
Tammannstr. 4
D-37077 Goettingen
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