On Apr 21, 2011, at 05:14 , Juliet Hannah wrote:

> As you mentioned, the deviance does not always reduce to:
> 
> D = -2(loglikelihood(model))
> 
> It does for ungrouped data, such as for binary logistic regression.

To be precise, it only happens when the log likelihood of the saturated model 
is 0, which for discrete models implies that the probability of the observed 
data under the saturated model is 1.  Binary data is pretty much the _only_ 
case where this is true (because individual fitted probabilities become either 
zero or one). 

-- 
Peter Dalgaard
Center for Statistics, Copenhagen Business School
Solbjerg Plads 3, 2000 Frederiksberg, Denmark
Phone: (+45)38153501
Email: pd....@cbs.dk  Priv: pda...@gmail.com

______________________________________________
R-help@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.

Reply via email to