Please, I have a problem with nonlinear quantile regression.
My data shows a large variability and the quantile regression seemed perfect to relate two given variables. I got to run the linear quantile regression analysis and to build the graph in the R (with quantreg package). However, the up part of my data dispersion seems a positive exponential curve, while the down part seems a negative exponential curve. The median part seems linear (maybe non-significant). I think that I needs to run a non-linear quantile regression for this dataset (including a tau = 0.1, 0.25, 0.5, 0.75 and 0.90 ). The problem is: I read very much many manuals about Quantile regression and the operational use of R, but I did not get to put parametrs in R to run this non-linear analysis. Might the function in R be the following? nlrq(formula, data=parent.frame(), start, tau=0.5, control, trace=FALSE,method="L-BFGS-B") What's the formula I could put here for my data?? How I put my file in this function? Might it be as [scan(file=read.dat" ]?? But where? At last, one confirmation: Can I run log X log analysis in nlrq?? Please, I need very much any response, as I don't know what make in this moment... Thank you very much, Humberto Marotta phD Student from Federal University of Rio de Janeiro [[alternative HTML version deleted]] ______________________________________________ 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.