[phenixbb] Optimizing the Geometry Weight for a 2.76 A structure

Edward A. Berry BerryE at upstate.edu
Fri Apr 2 15:08:11 PDT 2010

Edward A. Berry wrote:
>> sigma(Rfree)/Rfree ~ 1/sqrt(Ntest)
> I believe "~" here is read "proportional to", not "approximately".
No, seems it should be "approximately":
"Interestingly, the standard deviation of the free R value is approximately
given by Rfree/(n)^1/2, where n is the number of reflections in the test set."
Free R Value: Cross-Validation in Crystallography - AXEL T. BRUNGER METHODS IN ENZYMOLOGY, 
VOL. 277

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