The short answer to your question is that  quantile regression
estimates are estimating linear conditional quantile functions,
just like lm() is used to estimate conditional mean functions.

A longer answer would inevitably involve unpleasant suggestions
that you should follow the posting guide:

a.) send questions about packages to the maintainer, not R-help
b.) not attach datasets in modes that are stripped by R-help
c.) make a token effort to read the documentation and related literature




url:    www.econ.uiuc.edu/~roger                Roger Koenker
email   [EMAIL PROTECTED]                       Department of Economics
vox:    217-333-4558                            University of Illinois
fax:    217-244-6678                            Champaign, IL 61820

On Jun 29, 2004, at 10:26 AM, Ali Hirsa wrote:

I recently learn about Quantile Regression in R.
I am trying to study two time series (attached) by Quantile Regression in R.
I wrote the following code and do not know how to interpret the lines.


What kind of information can I get from them? Correlation for quantiles,
conditional probabilties (i.e. P(X in Quantile i | Y in Quantile i)) , and etc.
Many thanks in advance for any help.


Best,
Ali

library("quantreg")
#help.start()

Data <- read.table("RESvsMOVE2.dat")
#
x <- Data[,2]
y <- Data[,1]

par(mfrow=c(2,2))

qqnorm(x,main="MOVE Norm Q-Q Plot", xlab="Normal Qunatiles",ylab = "MOVE Quantiles")
qqline(x)


qqnorm(y,main="Residuals Norm Q-Q Plot", xlab="Normal Qunatiles",ylab = "Residuals Quantiles")
qqline(y)


plot(x,y,xlab="MOVE",ylab="Residuals",cex=.5)

xx <- seq(min(x),max(x),.5)

# Just a linear regression
g <- coef(lm(y~x))
yy <- (g[1]+g[2]*(xx))
lines(xx,yy,col="yellow")

taus <- c(.05,.1,.25,.5,.75,.9,.95)

for(tau in taus){
        f <- coef(rq(y~x,tau=tau,method="pfn"))
        yy <- (f[1]+f[2]*(xx))
        if (tau ==.05){
             lines(xx,yy,col="red")
        }
        if (tau ==.95){
             lines(xx,yy,col="green")
        }
        if (tau != .05 & tau != .95){
             lines(xx,yy,col="blue")
        }
}



                
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