Re: [ccp4bb] thin shell Rfree set selection

2014-08-13 Thread Eleanor Dodson 
It depends to a large extent on the orientation of the Ncs operator.

If that aligns with a crystal axis then there can be bias in the Rfree
selection but if it doesn't NCS does not affect the Free R much ( in my
opinion..)
Eleanor


On 13 August 2014 09:14, Ed Pozharski  wrote:

> By all means, try it both ways and see whether the R-Rfree gap narrows
> with random vs thin shell selection. Depending on resolution and data
> quality, you may also consider imposing NCS restraints.
>
>
> Sent on a Sprint Samsung Galaxy S® III
>
>
>  Original message 
> From: Xianchi Dong
> Date:08/12/2014 4:45 PM (GMT-05:00)
> To: CCP4BB@JISCMAIL.AC.UK
> Subject: [ccp4bb] thin shell Rfree set selection
>
> Dear all,
> I have a dataset of C2 symmetry and 2 molecules in the ASU. I am wondering
> if I have to use thin shell Rfree set selection to avoid Rfree bias by NCS.
> And which Rfree selection method is better?
>
> Thanks in advance.
>
> Xianchi
>

Re: [ccp4bb] thin shell Rfree set selection

2014-08-13 Thread Ed Pozharski 
By all means, try it both ways and see whether the R-Rfree gap narrows with 
random vs thin shell selection. Depending on resolution and data quality, you 
may also consider imposing NCS restraints.


Sent on a Sprint Samsung Galaxy S® III

 Original message From: Xianchi Dong 
 Date:08/12/2014  4:45 PM  (GMT-05:00) 
To: CCP4BB@JISCMAIL.AC.UK Subject: [ccp4bb] thin shell 
Rfree set selection 
Dear all,
I have a dataset of C2 symmetry and 2 molecules in the ASU. I am wondering if I 
have to use thin shell Rfree set selection to avoid Rfree bias by NCS. And 
which Rfree selection method is better?

Thanks in advance.

Xianchi

[ccp4bb] thin shell Rfree set selection

2014-08-12 Thread Xianchi Dong 
Dear all,
I have a dataset of C2 symmetry and 2 molecules in the ASU. I am wondering
if I have to use thin shell Rfree set selection to avoid Rfree bias by NCS.
And which Rfree selection method is better?

Thanks in advance.

Xianchi