I get
worms.glm <- glm(cbind(deaths, (20-deaths)) ~ sex+ doselin,
+ data=worms, family=binomial)
> attr(worms.glm, "dataClasses")
NULL
But maybe the result from somewhere within predict.lm() or model.frame()
is different.
Surely the levels attribute has no relevance to glm's c
Stripping attributes from a column in model.frame would be highly
undesirable.
The mistake was using 'unclass' when the intention was to remove the
levels (I presume). The new variable given is correctly reported as not
matching that used during fitting.
Uuse of traceback() would have shown t
The following is evidence of what is surely an undesirable feature.
The issue is the handling, in calls to model.frame(), of an
explanatory variable that has been derived as an unclassed
factor. (Ross Darnell drew this to my attention.)
## Data are slightly modified from p.191 of MASS
> worms <-
