On 19 Oct 2003 21:18:09 -0700, you wrote: >The problem seems to be that some of the values of d$Age.Month are 0 >and since the Weibull always has a value of 0 at 0, the log likelihood >comes out insane. (I'm getting 0 values due to quantization error). >OTOH when I remove the 0 values it works great, but that seems >kind of ad hoc. Is there some standard fix for this?
A standard fix is to replace zeros with some small positive number, but this isn't entirely satisfactory. It's definitely worthwhile doing a sensitivity test: e.g. do you get essentially the same answer using 0.01 and 0.0001 for the replacement value? If not, you might want to question the use of a model that predicts zero density in an area where you've got observations. Duncan Murdoch ______________________________________________ [EMAIL PROTECTED] mailing list https://www.stat.math.ethz.ch/mailman/listinfo/r-help
