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

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