Hi Andrew! Not sure if you are still working on this (apologies if I revived a dead thread) but you should not give up, if only because I am pretty much in the same boat; I have same data that looks like: f(161) = 53 f(169) = 53 f(160) = 55 f(168) = 55 f(170) = 59 f(174) = 59 f(171) = 61 really, it ...