Using the "ergoStool" data cited in Mixed-Effects Models in S and
S-PLUS by Pinheiro and Bates as an example, we have
========
> library(nlme)
> fm <- lme(effort~Type-1, data=ergoStool, random=~1|Subject)
> summary(fm)
Linear mixed-effects model fit by REML
Data: ergoStool
AIC BIC logLik
133.1308 141.9252 -60.5654
Random effects:
Formula: ~1 | Subject
(Intercept) Residual
StdDev: 1.332465 1.100295
Fixed effects: effort ~ Type - 1
Value Std.Error DF t-value p-value
TypeT1 8.555556 0.5760123 24 14.85308 0
TypeT2 12.444444 0.5760123 24 21.60448 0
TypeT3 10.777778 0.5760123 24 18.71102 0
TypeT4 9.222222 0.5760123 24 16.01046 0
Correlation:
TypeT1 TypeT2 TypeT3
TypeT2 0.595
TypeT3 0.595 0.595
TypeT4 0.595 0.595 0.595
Standardized Within-Group Residuals:
Min Q1 Med Q3 Max
-1.80200345 -0.64316591 0.05783115 0.70099706 1.63142054
Number of Observations: 36
Number of Groups: 9
========
Now suppose I want to test the following hypothesis
H0: TypeT1 =0 and TypeT2 = 0
I've tried estimable() and glh.test() in package gmodels, esticon() in
package boBy, and linear.hypothesis() in package car, but it seems
none of them would work with objects from lme:
========
> library(gmodels)
> estimable(fm, rbind(c("TypeT1"=1), c("TypeT2"=1)))
Error in FUN(newX[, i], ...) :
`param' has no names and does not match number of coefficients of
model. Unable to construct coefficient vector
> glh.test(fm, rbind(c("TypeT1"=1), c("TypeT2"=1)))
Error in glh.test(fm, rbind(c(TypeT1 = 1), c(TypeT2 = 1))) :
Only defined for lm,glm objects
> library(doBy)
> esticon(fm, rbind(c("TypeT1"=1), c("TypeT2"=1)))
Error in t(abs(t(tmp) * obj$fixDF$X)) :
dims [product 2] do not match the length of object [4]
In addition: Warning message:
In esticon.lme(fm, rbind(c(TypeT1 = 1), c(TypeT2 = 1))) :
The esticon function has not been thoroughly teste on 'lme' objects
> library(car)
> linear.hypothesis(fm, rbind(c("TypeT1"=1), c("TypeT2"=1)))
Error in L %*% b : requires numeric matrix/vector arguments
========
So is there any other package with which I can run this kind of tests?
Thanks,
Gang
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