Dear CCP4 users, I am a bit confused about the use of these terms in regards to structure refinement statistics. When I process my data with SCALA, the program outputs statistics in terms of "total and unique numbers of observations". However, when I use the MTZ files with REFMAC, the final PDB file has "number of reflections". These values are of similar magnitude, but not identical. The issue is even more complicated when I look at tables of statistics between different journals. Authors often report unique reflections or unique observations.
My questions are: 1) Are these two terms interchangable? 2) Are they relevant to the different stages of processing (e.g. data collection vs structure refinement)? 3) How do I rationalize the difference between the two values? I have read some of the widely used textbooks, but I am still confused when looking at publications. Any comments would be highly appreciated! Kind regards, Naveed Nadvi Faculty of Pharmacy, University of Sydney.
