On Thu, Jun 13, 2013 at 8:15 AM, Andrea Edwards <edwar...@stanford.edu>wrote:
> I have some rather (embarrassingly) basic questions to ask. Mainly.. when > deciding the resolution limit, which statistics are the most important? I > have always been taught that the highest resolution bin should be chosen > with I/sig no less than 2.0, Rmerg no less than 40%, and %Completeness > should be as high as possible. However, I am currently encountered with a > set of statistics that are clearly outside this criteria. Is it acceptable > cut off resolution using I/sig as low as 1.5 as long as the completeness is > greater than 75%? Another way to put this.. if % completeness is the new > criteria for choosing your resolution limit (instead of Rmerg or I/sig), > then what %completeness is too low to be considered? Also, I am aware that > Rmerg increases with redundancy, is it acceptable to report Rmerg (or Rsym) > at 66% and 98% with redundancy at 3.8 and 2.4 for the highest resolution > bin of these crystals? I appreciate any comments. > A (probably) better way: http://www.ncbi.nlm.nih.gov/pubmed/22628654 Short version: "don't try to use simplistic rules, instead use all data that actually improve the model". In practice, what I've noticed in some recent articles is (paraphrasing) "data extend to 2.5Å with an I/sigma of 2 in the highest-resolution shell, but we used data to 2.2Å as suggested by Karplus & Diederichs". This allows you to actually use as much data as possible while still (hopefully) pleasing any pedantic reviewers. (Substitute 90% completeness or R-merge of whatever for the I/sigma cutoff if you prefer, the end result will still be the same.) -Nat
