On Tue, 2008-01-01 at 15:16 +0100, Humberto Marotta wrote: > 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?
Well first you must put your data in a data frame sou you need type base<-scan(file="read.dat") Second is necessary look your data to understand the relations about your variables, I suggest: attach(base) plot(independent variable, dependent variable) So based in this plot you choose de formula of your data > > 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 > -- Bernardo Rangel Tura, M.D,MPH,Ph.D National Institute of Cardiology Brazil ______________________________________________ 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.
