[R] minor bug in lmer
Lngmyers
lngmyers at ccu.edu.tw
Wed May 9 08:29:20 CEST 2007
While playing around with the "(1|Subj)" syntax in lmer [lme4], I tried
out "(0|Subj)". It turns out that this is such a naughty thing to do
that it crashes the GUI in Windows! The parallel structure in lme [nlme]
has no effect. Try the following code to see for yourself.
# Make data set
q = 5; n = 5
Subj = NULL
X = NULL
Y = NULL
for (i in 1:q) {
for (j in 1:n) {
Subj = c(Subj,i)
X = c(X,j)
Y = c(Y,i/j)
}
}
fake = data.frame(Subj,X,Y)
# nlme
library(nlme)
fake.g.1 = groupedData(Y~1|Subj, data = fake)
fake.g.lme.1.1 = lme(Y ~ X, random=~1|Subj, data= fake.g.1)
fake.g.0 = groupedData(Y~0|Subj, data = fake)
fake.g.lme.0.0 = lme(Y ~ X, random=~0|Subj, data= fake.g.0)
fake.g.lme.1.0 = lme(Y ~ X, random=~1|Subj, data= fake.g.0)
fake.g.lme.0.1 = lme(Y ~ X, random=~0|Subj, data= fake.g.1)
# The following are all identical
summary(fake.g.lme.1.1)
summary(fake.g.lme.0.0)
summary(fake.g.lme.1.0)
summary(fake.g.lme.0.1)
# lme4
library(lme4)
# Same analysis as above:
fake.lme.1 = lmer(Y ~ X + (1|Subj),data=fake)
# The following line crashes the WinR GUI!
fake.lme.0 = lmer(Y ~ X + (0|Subj),data=fake)
--
James Myers
Graduate Institute of Linguistics
National Chung Cheng University
Web: http://www.ccunix.ccu.edu.tw/~lngmyers/
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