Bugs in packages are better sent to the maintainer than to R-bugs, as package maintainers do not in general have access to R-bugs.
This seems to me not to be a bug at all: the method has been correctly implemented. That the method is less then perfect is something you need to take up with the *authors* -- it would be wrong for me to change their code (especially since R itself has the Sheather-Jones method implemented, as well as MASS). If they want to change their S code the changes will percolate through to the R port eventually, but they may prefer to use the method they (I presume) give in their book. On Thu, 16 Jan 2003 [EMAIL PROTECTED] wrote: > Full_Name: J. E. Chac�n > Version: 1.6.2 > OS: Windows Millenium > Submission from: (NULL) (158.49.28.155) > > > Dear reader, > I am studying the bandwidth selection problem for density estimation. I have > read the popular Sheather & Jones (1991) article, in which this sj function is > based, to obtain (through function hsj) the bandwidth selector which appears in > that article. The problem is that the constants appearing in Sheather & Jones > paper are wrong, and this same (wrong) constants are used in the implementation > of the method for R. The (wrong) values are a=0.92*IQR*n^(-1/7) and > b=0.912*IQR*n^(-1/9). The constants there are wrong, the correct ones are: > - For a, (16*sqrt(2)/5)^(1/7)=~1.24 and > - For b, (32*sqrt(2)/7)^(1/9)=~1.23 > These corrected values appear, for instance, in the function width.SJ of MASS > library. > I hope this helps for improving this wonderful sm library. > Yours sincerely, > J.E. Chac�n > P.S.: Greetings from here for Professor Azzalini, who I met at his Smoothing > Methods course in Girona (Spain), last November, 2001. > > ______________________________________________ > [EMAIL PROTECTED] mailing list > http://www.stat.math.ethz.ch/mailman/listinfo/r-devel > -- Brian D. Ripley, [EMAIL PROTECTED] Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/ University of Oxford, Tel: +44 1865 272861 (self) 1 South Parks Road, +44 1865 272866 (PA) Oxford OX1 3TG, UK Fax: +44 1865 272595 ______________________________________________ [EMAIL PROTECTED] mailing list http://www.stat.math.ethz.ch/mailman/listinfo/r-devel
