Peter Dalgaard <p.dalgaard <at> biostat.ku.dk> writes: > > I'm not even sure we want to fix this up. I recall some nasty issues > with DF that have no proper solution that way - an observation with a > tiny weight represents an observation with a large variance and > contributes 1DF to the residual, with weight zero it is not supposed > to contribute at all, so there's a discontinuity for weights > approaching zero. >
with respect: is it worth adding a note to the documentation and/or a warning to the code? I understand that it becomes unwieldy to warn/protect against all "stupid"/unforeseen/suboptimal uses of the software, but I also understand how the original poster could have decided that setting a weight to zero was a plausible way to ignore cases ... there is already a warning that "observations with zero weight not used for calculating dispersion" -- could one modify this slightly to warn people against using zero weights? (Are zero weights always a bad idea?) Ben Bolker ______________________________________________ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel
