Re: [R] deviance in polr method

2009-01-13 Thread Prof Brian Ripley
On Tue, 13 Jan 2009, David Winsemius wrote: I remember have the same consternation using GLIM with binomial models on grouped and ungrouped data, but I was counseled by my betters only to consider differences in models. The differences in deviance are the same up to rounding error. 859.8018

Re: [R] deviance in polr method

2009-01-13 Thread David Winsemius
I remember have the same consternation using GLIM with binomial models on grouped and ungrouped data, but I was counseled by my betters only to consider differences in models. The differences in deviance are the same up to rounding error. > 859.8018 - 711.3479 [1] 148.4539 > 168.8-20.3 [1]

Re: [R] deviance in polr method

2009-01-13 Thread Prof Brian Ripley
Withut looking up your reference, are you not comparing grouped and ungrouped deviances? And polr() does not say anything about accepting a model (or not), only about the comparison between two models. 'Deviances' are in comparison with some 'saturated' model, and I would say that M&N are com

[R] deviance in polr method

2009-01-13 Thread Gerard M. Keogh
Dear all, I've replicated the cheese tasting example on p175 of GLM's by McCullagh and Nelder. This is a 4 treatment (rows) by 9 ordinal response (cols) table. Here's my simple code: cheese library(MASS) options(contrasts = c("contr.treatment", "contr.poly")) y = c