Quick workaround:
fm2 <- glm(accuracy ~ proficiency * task + proficiency/learner, viet,
family = binomial(), x=TRUE)
anova(fm2)
Analysis of Deviance Table
Model: binomial, link: logit
Response: accuracy
Terms added sequentially (first to last)
Df Deviance Resid. Df Resid. Dev
NULL 5592 4921.9
proficiency 1 57.5 5591 4864.4
task 4 131.7 5587 4732.6
proficiency:task 4 58.6 5583 4674.1
proficiency:learner 4 64.6 5579 4609.5
which looks more sensible.
The model matrix is being reconstructed incorrectly, hence the
discrepancies. I will look into that later.
On Thu, 29 Nov 2001 bates@stat.wisc.edu wrote:
anova.glm does not calculate the degrees of freedom properly when an explicit contrast has been set on a factor and the contrast has fewer than (len(levels(thisfactor)) - 1) columns.
load("/p/stat/course/st849-bates/public/slides/figs/src/viet.rda")
fm1 <- glm(accuracy ~ proficiency * task + proficiency/learner, viet,
+ family = binomial())
anova(fm1)
Analysis of Deviance Table
Model: binomial, link: logit
Response: accuracy
Terms added sequentially (first to last)
Df Deviance Resid. Df Resid. Dev
NULL 5592 4921.9
proficiency 3 69.5 5589 4852.4
task 4 132.9 5585 4719.5
proficiency:task 12 96.2 5573 4623.4
proficiency:learner 2 35.0 5571 4588.4
contrasts(viet$proficiency, 1) <- contrasts(viet$proficiency) contrasts(viet$proficiency)
.L l -0.6708204 m -0.2236068 h 0.2236068 a 0.6708204
fm2 <- glm(accuracy ~ proficiency * task + proficiency/learner, viet,
+ family = binomial())
anova(fm2)
Analysis of Deviance Table
Model: binomial, link: logit
Response: accuracy
Terms added sequentially (first to last)
Df Deviance Resid. Df Resid. Dev
NULL 5592 4921.9
proficiency 3 69.5 5589 4852.4
task 4 132.9 5585 4719.5
proficiency:task 12 96.2 5573 4623.4
proficiency:learner -6 13.9 5579 4609.5
The degrees of freedom for proficiency should be 1, for
proficiency:task should be 4 and for proficiency:learner should be 4.
The coefficient count is correct.
--please do not edit the information below--
Version:
platform = i386-pc-linux-gnu
arch = i386
os = linux-gnu
system = i386, linux-gnu
status = Under development (unstable)
major = 1
minor = 4.0
year = 2001
month = 11
day = 28
language = R
Search Path:
.GlobalEnv, package:Devore5, package:ctest, Autoloads, package:base
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