El 24/01/12 18:56, Greg Costakes escribió:
> Whoops, I misspoke... I meant Rsym and Rmerge increase with higher
> redundancies.
>
But then suppose that one merges data from a crystal that is degrading
while exposed, sp the data gets degraded. This is not at all unusual. In
the absence of a deep understanding of refinement, intuition suggests
that degraded data should produce degraded models. If Rwork and Rfree
are measuring anything useful they should go up redundancy in those
not-so-unusual cases. Or intuition is misguiding me again.
-- Miguel
> -------------------------------------------------------------------------------
> Greg Costakes
> PhD Candidate
> Department of Structural Biology
> Purdue University
> Hockmeyer Hall, Room 320
> 240 S. Martin Jischke Drive, West Lafayette, IN 47907
>
> --------------------------------------------------------------------------------
> ** Hard work often pays of in time, but Procrastination always pays off
> now **
>
> ------------------------------------------------------------------------
> *From: *"Dale Tronrud" <[log in to unmask]>
> *To: *"Greg Costakes" <[log in to unmask]>
> *Cc: *[log in to unmask]
> *Sent: *Tuesday, January 24, 2012 12:43:43 PM
> *Subject: *Re: [ccp4bb] Problem with getting Rfree and Rf down
>
>
> Is this observation about redundancies a general rule that I missed?
> It seems rather surprising to me. What have results have others seen?
>
> Dale Tronrud
>
> On 01/24/12 07:23, Greg Costakes wrote:
>> snip...
>
>> Higher redundancies (>7 or so) do tend to increase overall R/Rfree.
>
>> snip...
>>
> -------------------------------------------------------------------------------
>> Greg Costakes
>> PhD Candidate
>> Department of Structural Biology
>> Purdue University
>> Hockmeyer Hall, Room 320
>> 240 S. Martin Jischke Drive, West Lafayette, IN 47907
>>
>>
> --------------------------------------------------------------------------------
>> ** Hard work often pays of in time, but Procrastination always pays off
>> now **
>>
>> ------------------------------------------------------------------------
>> *From: *"Sam Arnosti" <[log in to unmask]>
>> *To: *[log in to unmask]
>> *Sent: *Monday, January 23, 2012 4:48:50 PM
>> *Subject: *[ccp4bb] Problem with getting Rfree and Rf down
>>
>> Hi every one
>>
>> I have some crystals in the space group P3121. I collect 180 frames of
> data.
>>
>> My crystals do not diffract better than at most 2.0 angstrom, but the Rf
>> barely goes below 23%,
>>
>> and Rfree also remains somewhere between 28-33%. I have tried to refine
>> my data as much as I can.
>>
>> I do not know whether the problem is because of the bad diffraction or
>> collecting extra frames.
>>
>> The structure factors are also high but they get better as the crystals
>> diffract better.
>>
>> Thanks
>>
>> Sam
--
Miguel
Architecture et Fonction des Macromolécules Biologiques (UMR6098)
CNRS, Universités d'Aix-Marseille I & II
Case 932, 163 Avenue de Luminy, 13288 Marseille cedex 9, France
Tel: +33(0) 491 82 55 93
Fax: +33(0) 491 26 67 20
mailto:[log in to unmask]
http://www.afmb.univ-mrs.fr/Miguel-Ortiz-Lombardia
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