pkoenker: A special distribution developed by Roger Koenker
Description
Density, distribution function, quantile function, random generation and expectile function
for a special distribution for which expectiles and quantiles coincide.
number of observations. If length(n) > 1, the length is taken to be the number required.
Value
dkoenker gives the density, pkoenker gives the distribution function,
qkoenker gives the quantile function, ekoenker gives the expectile function,
and rkoenker generates random deviates.
Details
This distribution has the distribution function:
$F(x) = \frac{1}{2}(1 + sgn(x) \sqrt{1 - \frac{4}{4 + x^2}})$
and the density:
$f(x) = \frac{2|x|}{(4+x^2)^2 \sqrt{1 - \frac{4}{4 + x^2}}}$
References
Koenker R (2005)
Quantile Regression
Cambridge University Press, New York