Hi helpeRs,
I've been working through some examples in Pinhiero & Bates( 2000)
trying to understand how to translate to the new Lme4 syntax but without
much luck.
Below is what I think I should do, but either the answers don't come out
the same or I get errors.
In the Oxide problems I'm particularly interested in obtaining the
levels coeficients but this options no longer seems to be available in
lme4. How can levels infor be obtained in lme4?
If someone can recreate the examples below in lme4 syntax so I can
follow what is happening in the text I'd be grateful.
Cheers
Paul Cossens
#Pixel
# P&B(2000) p40-45
Pixel<-read.csv("Pixel.csv",header=TRUE);
Pixel$Side<-as.factor(Pixel$Side)
Pixel$Dog<-as.factor(Pixel$Dog)
(fm1Pixel <- lmer(pixel ~ day + I(day^2) +(day|Dog)+(1|Side), data =
Pixel))
(fm2Pixel <- lmer(pixel ~ day + I(day^2) +(day|Dog), data = Pixel))
(fm3Pixel <- lmer(pixel ~ day + I(day^2) +(1|Dog:Side), data = Pixel))
or should I do it this way?
Pixel$DS<-with(Pixel,Dog:Side)[drop=TRUE]
(fm3Pixel <- lmer(pixel ~ day + I(day^2) +(1|DS), data = Pixel))
(fm4Pixel <- lmer(pixel ~ day + I(day^2) +Side , data = Pixel))
#Oxide
# P&B(2000) p167-170
Oxide<-read.csv("Oxide.csv",header=TRUE);
Oxide$Source<-as.factor(Oxide$Source)
Oxide$Lot<-as.factor(Oxide$Lot)
Oxide$Wafer<-as.factor(Oxide$Wafer)
Oxide$Site<-as.factor(Oxide$Site)
fm1Oxide<-lmer(Thickness~ (1|Lot)+(1|Lot:Wafer),data=Oxide) )
(fm2Oxide<-lmer(Thickness~ (1|Lot),data=Oxide) )
coef(fm1Oxide)
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