[phenixbb] Reflection file conversion

Pavel Afonine PAfonine at lbl.gov
Tue Jan 19 10:24:25 PST 2010

Hi Nate,

>> I was taught to set aside 10% for the free R set, only going lower
>> if setting aside the full 10% compromised completeness.  I'm just
>> wondering what is the rationale for the numeric cap?  Am I making
>> any error(s) with my methodology?
> For the alpha/beta (or sigmaa) calculation you need a certain number
> of reflections per resolution bin to get reasonable estimates. Say
> you have 10 bins, 2000/10 = 200 is a sufficiently large sample per
> bin.
> I have to admit I'm uncertain about the pros and cons of setting
> aside a larger number of reflections.

Test reflections are not used in map calculation. So obviously, more 
reflections you exclude as free reflections, less reflections will be 
used in map calculation. Personally, I've never seen this being a 
trouble but the rumor is that this may worsen the maps.

I think the way PHENIX generates free-flags for you is totally fine 
(unless you prove otherwise).


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