Hi Jorge, the answer probably depends to some extent on what you need the numbers for. The statistical error of the indicators is inversely proportional to the square root of the number of reflections. I seem to remember publications in the field of maximum likelihood refinement which report that the number of "free" reflections in a resolution shell should be at least on the order of about 50 or so to give reliable estimates of maximum likelihood parameters. Of course more reflections improve the estimates, but then less shells are the consequence. The best compromise will probably sit in a shallow optimum, so it does not matter too much if you deviate from it.
best, Kay On Mon, 20 Feb 2017 08:19:09 -0300, Jorge Iulek <[email protected]> wrote: ><html> > <head> > <meta http-equiv="content-type" content="text/html; charset=UTF-8"> > </head> > <body text="#000000" bgcolor="#FFFFFF"> > <font size="+1"><font face="Times New Roman, Times, serif">Dear all,<br> > <br> > Is there any study to recommend the (minimum) number of > reflections for adequate statistics in each shell during image > processing? I mean, for indexes like R_meas or R_symm or CC1/2, > it might be important to know the number of total reflections > and unique reflections in the shell, maybe these numbers might > be different for indexes like <I/sigI>. I am not properly > talking about the best index here, yet there have been many > indications that CC1/2 should be a preferred one, but rather, > how thin can the shell be (id est, related to the number of bins > we should consider better according to the resolution).<br> > I have yet other question, a kind of related one. But I will > prefer to separate (and the discussion thus derived) in other > email.<br> > Thanks,<br> > <br> > Jorge<br> > <br> > </font></font> > </body> ></html>
