Dear Faisal,
 
I might be missing something, but why not ask the annotator instead of the bulletin board? He should know which value is meant. For me, a sigma belongs to a set of observations or parameters and without any further information one can only guess (as Ed just did) which set. My guess would be, that instead of structure file, structure factor file was meant and that somehow a negative sigma slipped in for one of the structure factors, but again that is just guessing.
 
My two cents,
Herman
 


Von: CCP4 bulletin board [mailto:[log in to unmask]] Im Auftrag von Faisal Tarique
Gesendet: Montag, 17. Juni 2013 08:41
An: [log in to unmask]
Betreff: [ccp4bb] sigma value in structure file

Dear all

During PDB deposition the annotator me to verify and review the sigma value in the structure file which in my case was -0.03. I have some basic queries and request you all to please answer them. My first question is, what actually is a "sigma value" of a structure file. 2nd) where the value is mentioned?. 3rd) and What is the optimum sigma value range ?

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Regards

Faisal
School of Life Sciences
JNU