On 10 Jan, 2006, at 14:58, [EMAIL PROTECTED] wrote: >>>>>> "Heather" == Heather Turner <[EMAIL PROTECTED]> >>>>>> on Tue, 10 Jan 2006 14:30:23 +0100 (CET) writes: > > Heather> This bug is not quite fixed - the example from my > Heather> original report now = works using R-2.2.1, but > > Heather> plot(Uniform, 6) > > Heather> does not. The bug is due > > ......... > g <- hatval/(1 - hatval) # Potential division by zero here > > plot(g, cook, xlim = c(0, max(g)), ylim = c(0, ymx), > .......... > > Heather> All other values of 'which' seem to work > Heather> fine. Sorry not to have checked this in the beta > Heather> version, > > (indeed; that would have been useful) > > > Hmm, it's not clear what *should* be drawn in such a > case. Leaving away all the observations with h_ii = 1 > seems a particularly bad idea, since these are the ones that > you'd definitely should remark. > OTOH, for h_ii = 1, the cook distance is 'NaN' > (or should that be changed; to "very large" instead ???) > and plot number 6 doesn't seem to make any sense to me > > When 'which = 6' was proposed > [ on R-devel as well, last April, > http://tolstoy.newcastle.edu.au/R/devel/05/04/0595.html > ah, I see, by David Firth, from your place, so, Heather, can you > make sure he sees this e-mail ? > ] > I actually had wondered a bit about it's general usefulness,..
Yes, I remember that there was some discussion of this last year, and my recollection is that it was mostly luke-warm at best in regard to including this plot. The "h_ii = 1" problem can of course be taken care of by leaving out such points if they can be reliably detected, but I share Martin's unease about this. We should also worry about for example h_ii = (1 - epsilon), with epsilon small, as plotting such a point would effectively make the rest of the graph useless. Maybe it would be safest to remove the which=6 option? David ______________________________________________ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel
