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Hi Folks, Many thanks for all of your comments - in keeping with the spirit of the BB I have digested the responses below. Interestingly I suspect that the responses to this question indicate the very wide range of resolution limits of the data people work with! Best wishes Graeme =================================== Proposal 1: 10% reflections, max 2000 Proposal 2: from wiki: http://strucbio.biologie.uni-konstanz.de/ccp4wiki/index.php/Test_set including Randy Read "recipe": So here's the recipe I would use, for what it's worth: <10000 reflections: set aside 10% 10000-20000 reflections: set aside 1000 reflections 20000-40000 reflections: set aside 5% >40000 reflections: set aside 2000 reflections Proposal 3: 5% maximum 2-5k Proposal 4: 3% minimum 1000 Proposal 5: 5-10% of reflections, minimum 1000 Proposal 6: > 50 reflections per "bin" in order to get reliable ML parameter estimation, ideally around 150 / bin. Proposal 7: If lots of reflections (i.e. 800K unique) around 1% selected - 5% would be 40k i.e. rather a lot. Referees question use of > 5k reflections as test set. Comment 1 in response to this: Surely absolute # of test reflections is not relevant, percentage is. ============================ Approximate consensus (i.e. what I will look at doing in xia2) - probably follow Randy Read recipe from ccp4wiki as this seems to (probably) satisfy most of the criteria raised by everyone else. On Tue, Jun 2, 2015 at 11:26 AM Graeme Winter <[log in to unmask]> wrote: > Hi Folks > > Had a vague comment handed my way that "xia2 assigns too many free > reflections" - I have a feeling that by default it makes a free set of 5% > which was OK back in the day (like I/sig(I) = 2 was OK) but maybe seems > excessive now. > > This was particularly in the case of high resolution data where you have a > lot of reflections, so 5% could be several thousand which would be more > than you need to just check Rfree seems OK. > > Since I really don't know what is the right # reflections to assign to a > free set thought I would ask here - what do you think? Essentially I need > to assign a minimum %age or minimum # - the lower of the two presumably? > > Any comments welcome! > > Thanks & best wishes Graeme >