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:[email protected]] Im Auftrag von Faisal Tarique Gesendet: Montag, 17. Juni 2013 08:41 An: [email protected] 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 ? -- Regards Faisal School of Life Sciences JNU
