[R] Non-linear regression/Quantile regression

Gabor Grothendieck ggrothendieck at gmail.com
Tue Jun 9 17:21:58 CEST 2009


Those are linear in the coefficients so try these:

library(quantreg)

rq1 <- rq(demand ~ Time + I(Time^2), data = BOD, tau= 1:3/4); rq1

# or
rq2 <- rq(demand ~ poly(Time, 2), data = BOD, tau = 1:3/4); rq2


On Tue, Jun 9, 2009 at 10:55 AM, despaired<meyfarth at uni-potsdam.de> wrote:
>
> Hi,
>
> I'm relatively new to R and need to do a quantile regression. Linear
> quantile regression works, but for my data I need some quadratic function.
> So I guess, I have to use a nonlinear quantile regression. I tried the
> example on the help page for nlrq with my data and it worked. But the
> example there was with a SSlogis model. Trying to write
>
> dat.nlrq <- nlrq(BM ~ I(Regen100^2), data=dat, tau=0.25, trace=TRUE)
>
> or
>
> dat.nlrq <- nlrq(BM ~ poly(Regen100^2), data=dat, tau=0.25, trace=TRUE)
>
> (I don't know the difference) both gave me the following error message:
>
> error in getInitial.default(func, data, mCall = as.list(match.call(func,  :
>  no 'getInitial' method found for "function" objects
>
> Looking in getInitial, it must have to do something with the starting
> parameters or selfStart model. But I have no idea, what this is and how I
> handle this problem. Can anyone please help?
>
> Thanks a lot in advance!
> --
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>
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