Please tell me why Rpim should be looked at. Cannot one have meaningless data
and have lots of multiplicity to drive Rpim lower without any real benefit?
Under what conditions is Rpim useful?
And suppose one looks at <I/sigI> (and not <I>/<sigI>) and CC1/2. What of it?
And let me write what Phil wrote in a slightly different way:
Please explain how you think that adding the resolution from 2.6 A to 2.45 A
will improve your model.
Sorry, but maybe it is too soon after the last CC1/2 discussion to raise these
points, but I am truly interested in various opinions about all this.
________________________________________
From: CCP4 bulletin board [CCP4BB@JISCMAIL.AC.UK] on behalf of Gerard Bricogne
[g...@globalphasing.com]
Sent: Thursday, October 10, 2013 5:28 PM
To: CCP4BB@JISCMAIL.AC.UK
Subject: Re: [ccp4bb] how to cut back resolution of a well-refined model
Dear Yafang,
Is it the case that you collected these data on a Pilatus detector,
using relatively low exposure and high multiplicity? These types of datasets
always give what looks like alarmingly high values of R-merge, and many
people who are set in their ways (like so many reviewers still are) tend to
conclude that the alarm is about the data being bad, whereas it is about
Rmerge being a terrible statistic in these situations. The Rpim statistic,
on the other hand, is the one to look at if you want an R-like quantity, and
it is well behaved in this regime. Of course, look at CC1/2 as well, and
I/sigI as you did.
With best wishes,
Gerard.
--
On Thu, Oct 10, 2013 at 04:57:20PM -0400, Yafang Chen wrote:
> Hi All,
>
> I have a structure at 2.45A which has been well refined. However, since the
> R-merge at the last shell is above 1 (although I/sigmaI at the last shell
> is more than 2), we now decide to cut back the resolution to about 2.6A. Is
> there a way to do this based on the well-refined model instead of doing the
> MR and refinement all over again? Thank you so much for your help!
>
> Best,
> Yafang
>
> --
> Yafang Chen
>
> Graduate Research Assistant
> Mesecar Lab
> Department of Biological Sciences
> Purdue University
> Hockmeyer Hall of Structural Biology
> 240 S. Martin Jischke Drive
> West Lafayette, IN 47907
--
===============================================================
* *
* Gerard Bricogne g...@globalphasing.com *
* *
* Global Phasing Ltd. *
* Sheraton House, Castle Park Tel: +44-(0)1223-353033 *
* Cambridge CB3 0AX, UK Fax: +44-(0)1223-366889 *
* *
===============================================================
