On 2010-10-02 11:47, Luciano Selzer wrote:
Dear List,
I find Effects package very useful, but I believe I have found a bug in
allEffects function. Please consider the following code:
test<- data.frame(tries= round(runif(40, 5, 300)),
tra = gl(4, 10, labels = c("V", "D", "C", "L")),
prop= runif(40, 0, 1))
test$success<- round(with(test, tries*prop))
test$prop<- with(test, success/tries)
model<- glm( cbind(success, tries) ~ -1 + tra, data = test, family =
binomial)
allEffects(model)
#Error en eval(expr, envir, enclos) : objeto 'tra' no encontrado
model2<- glm( prop ~ -1 + tra, weights = tries, data = test, family =
binomial)
allEffects(model2)
#Works
On a quick search on the internet I've found nothing about this. Is this a
bug?
I think that this is indeed a bug, probably due to the use of
the all.vars() function in effects:::analyze.model().
The obvious workaround is to specify your model as in model2
above or, if you want to use the matrix-response version, then
give the matrix a name and use that in your model:
respmat <- with(test, cbind(success, tries - success))
##[correcting your cbind]
mod <- glm(respmat ~ ....)
-Peter Ehlers
Thanks for your time
Luciano
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