@JISCMAIL.AC.UK] on behalf of Eleanor Dodson
[eleanor.dod...@york.ac.uk]
Sent: Wednesday, August 08, 2012 12:10 PM
To: CCP4BB@JISCMAIL.AC.UK
Subject: Re: [ccp4bb] CC1/2, XDS and resolution cut off
Like Ian, I tend to use as much data as is reasonable - but it is useful to
look at the Rfactors plot
Eleanor
But is the R factor a good way to assess this? - in fact who cares if
R looks worse, the goal of structure refinement after all is certainly
not to get a better R factor! The R factor if it's anything is a
measure of comparative model quality, not comparative data quality.
What I mean is
Begin forwarded message:
From: Eleanor Dodson eleanor.dod...@york.ac.uk
Subject: Re: [ccp4bb] CC1/2, XDS and resolution cut off
Date: 8 August 2012 10:10:55 GMT+01:00
To: Marcus Fislage marcus.fisl...@vib-vub.be
Cc: CCP4BB@JISCMAIL.AC.UK
Like Ian, I tend to use as much data
Dear all,
We have in our lab a data set collected and are discussing where to cut
the resolution for refinement. According to the work of Kai Diederichs
and Andy Karplus one should use CC 1/2 of 12.5% (in case it is
significant) to determine the highest resolution independent of the
I/sigI and R
Hi Marcus
I don't use CC(1/2) as a criterion for cut-off though I do keep an eye
on it. It's not clear to me how you apply the CC(1/2) criterion when
the data are incomplete (as they invariably are). Also there seems to
be some debate whether the cut-off should be at CC = 0.5 or much
lower,
Ian Tickle wrote:
below the noise threshold. This does make the tacit assumption that
the unmeasured reflections are distributed randomly in reciprocal
space, which is clearly not entirely true, but it's hard to see how
one could account for the non-random distribution. Again, in any case
Oh - you meant how one could take nonrandom distrubution
into account in the analysis-
funny how I always understand what someone meant after
i push send on an inappropriate reply
Edward A. Berry wrote:
Ian Tickle wrote:
below the noise threshold. This does make the tacit assumption that
the
Hello
Edward A. Berry wrote:
What about collecting in the corners of a square detector?
Due to the crystal diffracting better than expected or
the need to sacrifice resolution for spot separation?
This is actually our reason that we have problem. The strategy initially
suggested lower
Do you think that this averaged I/sig I could also be transferred to a
averaged CC1/2 giving unobserved spots a CC1/2 of 0.
-- CC1/2_all = shell_completeness * CC1/2_measured?
Actually yes it did occur to me (just after I hit 'send') that that
would be just as valid (or invalid depending on
Dear Marcus,
I have a few comments:
- we do not suggest any fixed value (like 0.125) for a CC1/2 cutoff. One reason
why a fixed value should not be carved in stone is that future data processing
and refinement programs might extract more information from the weak data than
current ones do.
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