Maia,
provided radiation damage is not a major detrimental factor, your data
are just fine, and useful also in the high resolution shell (which still
has <I/sigma> of 2.84 so you could probably process a bit beyond 2.25A).
There is nothing wrong with R_meas of 147.1% since, as others have said,
R_meas is not limited to 59% (or similar) as a refinement R-factor is.
Rather, R_meas is computed from a formula that has a denominator which
in the asymptotic limit (noise) approaches zero - because there will be
(almost) as many negative observations as positive ones! (The numerator
however does not go to zero)
Concerning radiation damage: First, take a look at your frames - but
make sure you have the same crystal orientation, as anisotropy may mask
radiation damage! Then, you can check (using CCP4's loggraph) the R_d
plot provided by XDSSTAT (for a single dataset; works best for
high-symmetry spacegroups), and you should also check ISa (printed in
CORRECT.LP and XSCALE.LP).
HTH,
Kay
P.S. I see one potential problem: "XSCALE (VERSION December 6, 2007)"
when the calculation was done 28-Aug-2009. There were quite a number of
improvements in XDS/XSCALE since that version. The reason may be that a
licensed, non-expiring version was used - make sure you always rather
use the latest version available!
> -------- Original Message --------
> Subject: [Fwd: Re: [ccp4bb] I/sigmaI of >3.0 rule]
> Date: Thu, 3 Mar 2011 10:45:03 -0700
> From: Maia Cherney <[log in to unmask]>
>
>
>
> -------- Original Message --------
> Subject: Re: [ccp4bb] I/sigmaI of >3.0 rule
> Date: Thu, 03 Mar 2011 10:43:23 -0700
> From: Maia Cherney <[log in to unmask]>
> To: Oganesyan, Vaheh <[log in to unmask]>
> References: <[log in to unmask]>
> <[log in to unmask]>
> <[log in to unmask]>
> <[log in to unmask]> <[log in to unmask]>
> <[log in to unmask]>
>
>
>
> Vaheh,
>
> The problem was with Rmerg. As you can see at I/sigma=2.84, the Rmerge
> (R-factor) was 143%. I am asking this question because B. Rupp wrote
> "However, there is a simple relation between <I/sigI> and R-merge
> (provided no other indecency has been done to the data). It simply is
> (BMC) Rm=0.8/<I/sigI>."
> Maybe my data are indecent? This is the whole LP file.
>
> Maia
>
> MMC741_scale-2.25.LP
>
>
>******************************************************************************
> XSCALE (VERSION December 6, 2007) 28-Aug-2009
>******************************************************************************
>
> Author: Wolfgang Kabsch
> Copy licensed until (unlimited) to
> Canadian Light Source, Saskatoon, Canada.
> No redistribution.
>
--
Kay Diederichs http://strucbio.biologie.uni-konstanz.de
email: [log in to unmask] Tel +49 7531 88 4049 Fax 3183
Fachbereich Biologie, Universität Konstanz, Box M647, D-78457 Konstanz
This e-mail is digitally signed. If your e-mail client does not have the
necessary capabilities, just ignore the attached signature "smime.p7s".
|