Thank you Tim and Pavel.

Sorry, just to follow up:

For the example I gave R /Rfree difference seems high. Can this still be down to statistical fluctuations?

I am just trying to get a feel when we can simply put it down to statistical fluctuations and when its a concern.

On Mon, Jan 26, 2015 at 4:26 PM, Tim Gruene <tg@shelx.uni-ac.gwdg.de> wrote:

Dear George,

you may also want to take into account that the variation of Rfree is
estimated as Rfree^2/k, where k is the number of reflections in the
shell. If you only have e.g. 100 reflections there, this might simply a
statistical fluctuation, as far as I understand.

Cheers,
Tim

On 01/26/2015 10:05 PM, George Devaniranjan wrote:
> Hi,
>
> I calculated/validated several PDB structures in Phenix.Validation (GUI)
>
> The R/R-free (overall) is
>
> 0.1271/0.1348
>
> Further down I looked at the R/R-free for the highest resolution shell.
>
> Its 0.2538/0.2446
>
> I am curious why the R-free for the *highest resolution shell* seems to be
> LOWER than R (work).
>
>
> Am I reading the information wrong?
>
> PDB: 3QL9
>
> Thank you,
> George
>
>
>

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--
Dr Tim Gruene
Institut fuer anorganische Chemie
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D-37077 Goettingen

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