[R-sig-ME] Replicating type III anova tests for glmer/GLMM
Emmanuel Curis
emmanuel.curis at parisdescartes.fr
Tue Feb 23 17:49:47 CET 2016
Dear Pr Fox,
Thanks for your precision. But to summarize this test of, let's say 3
parameters to 0 for a 4-levels factor, by a single value with its SE,
as mentionned in Francesco's mail, the linear combination of these
parameters that is practically tested by this sum of square is needed,
isn't it ?
I mean, if really the parameters are all 0, whatever linear
combination could do the job, but type III sum of square just tests
one of all possible linear combinations, right?
By the way, I was always very annoyed by the fact that Type III sum of
squares are so dependent on coding, but that's another debate...
Best regards,
On Tue, Feb 23, 2016 at 04:15:02PM +0000, Fox, John wrote:
« Dear Emmanuel,
«
« With proper contrast coding (i.e., a coding that's orthogonal in the *basis* of the design, such as provided by contr.sum() ), a "type-III" test is just a test that the corresponding parameters are 0. The models in question are generalized linear (mixed) models and so sums of squares aren't really involved, but one could do the corresponding Wald (like car::Anova) or LR test. The Wald test is what you'd get with multcomp:glht or car:linearHypothesis. BTW, I don't think that it would be hard for car::Anova to be extended to provide LR tests in this case.
«
« Best,
« John
--
Emmanuel CURIS
emmanuel.curis at parisdescartes.fr
Page WWW: http://emmanuel.curis.online.fr/index.html
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