-----Original Message-----
From: r-sig-mixed-models-bounces at r-project.org
[mailto:r-sig-mixed-models-bounces at r-project.org] On Behalf Of Divaker
Sent: Monday, November 26, 2007 9:26 PM
To: r-sig-mixed-models at r-project.org
Subject: [R-sig-ME] lme - nested - One fixed effect and
another within thatas random effect
Dear R mixed model Users and Dr. Bates,
I am trying to work out a problem given in Nested design -
Design of Experiments by Montgomery - p.561 using lme It is
a mixed model with Supplier as fixed effect and batches
within the supplier as random effects.
When I tried my hands on lmer instead of lme, I get what is
required as below.
proclme=lmer(Purity~Supplier+(1|Supplier:Batch),process)
print(summary(proclme))
Linear mixed-effects model fit by REML
Formula: Purity ~ Supplier + (1 | Supplier:Batch)
Data: process
AIC BIC logLik MLdeviance REMLdeviance
150.8 157.2 -71.42 146.9 142.8
Random effects:
Groups Name Variance Std.Dev.
Supplier:Batch (Intercept) 1.7162 1.3100 Here we have
the variance of random effect exactly as in the book
Residual 2.6368 1.6238
number of obs: 36, groups: Supplier:Batch, 12
Fixed effects:
Estimate Std. Error t value
(Intercept) -0.4167 0.8055 -0.5173
SupplierT2 0.7500 1.1391 0.6584
SupplierT3 1.5833 1.1391 1.3900
Correlation of Fixed Effects:
(Intr) SpplT2
SupplierT2 -0.707
SupplierT3 -0.707 0.500
But using lme, it is not working. Is there any way out.lme is
not accepting the format random=~1|Supplier : Batch I am more
comfortable using lme since the supporting docs are exaustive
and we have access to many support functions for lme
This code is not appropriate and also not working
library(nlme)
proclme=lme(Purity~Supplier,random = ~1|Supplier/Batch,process)
summary(proclme)
VarCorr(proclme)
Divaker
Dr. C. Divaker Durairaj, ME, Ph.D
Professor, Farm Machinery
Agricultural Machinery Research Centre
Tamil Nadu Agricultural University
Coimbatore 641003, India
Ph: 91-422-6611204
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