On Mar 9, 2012, at 4:36 PM, Max Kuhn wrote:

Can anyone recommend a good nonparametric density approach for data bounded
(say between 0 and 1)?

I thought the "canonical" answer, at least the one that generally is put forward whe people have difficulty with the stats::spline results was to turn to function 'logspline' in package logspline.


For example, using the basic Gaussian density approach doesn't generate a
very realistic shape (nor should it):

set.seed(1)
dat <- rbeta(100, 1, 2)
plot(density(dat))

require(logspline)
set.seed(1)
dat <- rbeta(100, 1, 2)
lsdat <- logspline(dat, lbound=0,ubound=1)
plot(lsdat)

# yield sharp edges to density.


(note the area outside of 0/1)

The data I have may be bimodal or have other odd properties (e.g. point
mass at zero).

Ah, the Dirac function. (Just my physics background showing.)

HTH;
David.

I've tried transforming via the logit, estimating the
density then plotting the curve in the original units, but this seems to do
poorly in the tails (and I have data are absolute zero and one).

Thanks,

Max

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