output on glm.nb

2 messages · Ronaldo Reis Jr., Brian Ripley

Thu, Nov 28, 2002 10:32 AM #

Hi,
I make a model and have compared with null model.

anova(mnull,m1)

	Model theta Resid. df 2xlog-lik   test   df   LR stat.  Pr(chi)
1	...   0.39    161     -577.9129          NA   NA        NA
2	...   1.30    150     -475.6839  1 vs 2  11   102.229   1.11e10-16

anova(m1)

	Df  Deviance   Resid. Df   Resid. Dev   P(>|chi|)
NULL                      161         282.139    9...
...     ...    ...        ...           ...       ...
last    2    8.824        150         138.154     ...

My doubt is:

What is my null deviance? 577.9129 or 282.139?

What is 2xlog-lik?

Thanks
Ronaldo

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Brian Ripley

Thu, Nov 28, 2002 11:40 AM #

glm.nb is part of MASS, although you give no credit.  If you read the book
which this software supports you will find worked examples.

Read ?anova.negbin (more) carefully: it does explain this.

On Thu, 28 Nov 2002, Ronaldo Reis Jr. wrote:

Only one entry is labelled as a `deviance', so just read more carefully.

Twice the log-likelihood, of course.

Brian D. Ripley,                  ripley at stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
1 South Parks Road,                     +44 1865 272860 (secr)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595

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