>> How about smoothing the percentages, and then take the second >> derrivative to find the inflection point? >> >> which.max(diff(diff((lowess(percentages)$y)))) > > This solution is what I've been using so far. The only difference is that I am smoothing the 1st derivative, since its > the one I want to be smooth, smoothing the percentages curve does not produce good results.
I've noticed something: What I am using is something like: which.max(abs(diff(sign(diff(diff(lowess(percentages)$y)))))) "The fist value where the 2nd derivative changes its sign" To find the f''(x)=0 But you have suggested the max value of the 2nd derivative. Regards, Jose Lozano ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
