(a) For the bandwidth matrix selectors, there are several varieties:
(i) plug-in
Hpi, Hpi.diag
(ii) least squares (or unbiased) cross validation (LSCV or UCV)
Hlscv, Hlscv.diag,
(iii) biased cross validation (BCV)
Hbcv, Hbcv.diag and
(iv) smoothed cross validation (SCV)
Hscv, Hscv.diag.
The first selector in each pair is the unconstrained (or full)
selector, and the second one is the diagonal selectors.
A scalar plug-in bandwidth selectors is implemented as
hpi. The code is taken from the dpik selector
in the kde. For kernel discriminant analysis, it's kda.kde.
(c) For display, versions of plot, plot.kde and
plot.kda.kde, send to a graphics window
the results of density estimation or discriminant analysis.
For d = 1, 2, 3, 4, binned kernel estimation is available.
For an overview of this package with 2-dimensional density estimation, see
vignette("kde").
Chac'on, J.E. & Duong, T. (2008) Multivariate plug-in bandwidth selection with unconstrained pilot matrices. Submitted. Duong, T. (2004) Bandwidth Matrices for Multivariate Kernel Density Estimation. Ph.D. Thesis. University of Western Australia. Duong, T. & Hazelton, M.L. (2003) Plug-in bandwidth matrices for bivariate kernel density estimation. Journal of Nonparametric Statistics, 15, 17-30. Duong, T. & Hazelton, M.L. (2005) Cross-validation bandwidth matrices for multivariate kernel density estimation. Scandinavian Journal of Statistics, 32, 485-506.
Sain, S.R., Baggerly, K.A. & Scott, D.W. (1994) Cross-validation of multivariate densities. Journal of the American Statistical Association. 82, 1131-1146.
Scott, D.W. (1992) Multivariate Density Estimation: Theory, Practice, and Visualization. John Wiley & Sons. New York.
Silverman, B. (1986) Density Estimation for Statistics and Data Analysis. Chapman & Hall/CRC. London.
Simonoff, J. S. (1996) Smoothing Methods in Statistics. Springer-Verlag. New York.
Wand, M.P. & Jones, M.C. (1994) Multivariate plugin bandwidth selection. Computational Statistics, 9, 97-116. Wand, M.P. & Jones, M.C. (1995) Kernel Smoothing. Chapman & Hall/CRC. London.
sm, KernSmooth