Re: [ccp4bb]: Phasing Phoiled by Phistats in Philadelphia. Pfui.

["Eleanor J. Dodson" <ccp4@ysbl.york.ac.uk>]

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"Patrick J. Loll" wrote:
> 
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> I'm confused about output I obtain from phistats.  I'm attempting to
> calculate the phase errors associated with various phasing procedures.
> I've written a little program to calculate the quantity:
> 
> <|deltaPhi|> = the mean value over all reflxns of the absolute value of the
>                difference between Phi1 and Phi2.  I calculate this for all
>                reflxns and for acentrics only
> 


I dont think phistats is wrong but will check.

 Do you always convert the difference to lie in the range 0-180?

ie if one phase is 10 and the other 350, then the difference is 20 not
340..

 The best test is that two sets of random phases should differ by 90 ..


But a plug for phistats:
 the unweighted phase difference doesnt mean much if the FOMs are ~ 0.00 

 the weighted diff is more meaningful.

Eleanor