On Thu, 2011-03-03 at 09:34 -0600, Jim Pflugrath wrote:
> As mentioned there is no I/sigmaI rule. Also you need to specify (and
> correctly calculate) <I/sigmaI> and not <I>/<sigmaI>.
>
> A review of similar articles in the same journal will show what is
> typical
> for the journal. I think you will find that the <I/sigmaI> cutoff
> varies.
> This information can be used in your response to the reviewer as in,
> "A
> review of actual published articles in the Journal shows that 75% (60
> out of
> 80) used an <I/sigmaI> cutoff of 2 for the resolution of the
> diffraction
> data used in refinement. We respectfully believe that our cutoff of 2
> should be acceptable."
>
Jim,
Excellent point. Such statistics would be somewhat tedious to gather
though, does anyone know if I/sigma stats are available for the whole
PDB somewhere?
On your first point though - why is one better than the other? My
experimental observation is while the two differ significantly at low
resolution (what matters, of course, is I/sigma itself and not the
resolution per se), at high resolution where the cutoff is chosen they
are not that different. And since the cutoff value itself is rather
arbitrarily chosen, then why <I/sigma> is better than <I>/<sigma>?
Cheers,
Ed.
--
"I'd jump in myself, if I weren't so good at whistling."
Julian, King of Lemurs
