# [R] lme

Peter B. Mandeville mandevip at uaslp.mx
Thu Jul 1 06:02:14 CEST 1999

```I am using rw0641.

In my continuing quest to understand repeated measures analysis, I again
return to lme. I exported the Potthoff and Roy data Orthodont.dat from
S-PLUS 4.5 to avoid capture errors and ran the examples in the R help. I
imported the data.frame with

attach(data)

and created the objects

Orthodont.fit1 <- lme(fixed=distance~age,random=~age)
Orthodont.fit2 <- lme(fixed=distance~age*Sex,random=~age)

which appear to be the R equivalent of the objects created in Pinheiro and
Bates 1995 (lme and nlme).

The code

fm1 <- lmList(distance~age|Subject,data)

generated the error message

Error: couldn't find function "restart"

without 'data' it doesn't run.

The code

plot(Orthodont.fit1)

generated the error message

Error: couldn't find function "xyplot"

I suppose that a graph such as appears in Pinheiro and Bates 1995 (lme and
nlme) and in S-PLUS4 : Guide to Statistics is generated by the plot method?
The code given in S-PLUS4 : Guide to Statistics page 285 does generate the
graph.

plot(age,distance,type="n",xlab="Age (years)",ylab="Distance (mm)")
points(age[Sex=="0"],distance[Sex=="0"],type="p",pch=0)
points(Age[Sex=="1"],distance[Sex=="1"],type="p",pch=5)
for(i in unique(Subject))
lines(Age[Subject==i],distance[Subject==i],type="l",lty=2)

The function numIter doesn't function

Orthodont.fit1\$numIter

produces

NULL

Most distressing is the fact that

summary(Orthodont.fit2)

produces the same fixed effects values

(Intercept) 	16.340625
Age		0.784375
Sex		1.032102
Age.Sex		-0.0304830

as Pinheiro and Bates 1995 (lme and nlme) but everything else is very
distinct.

Thank you very much.

Peter B.

--
Peter B. Mandeville                             mandevip at deimos.tc.uaslp.mx
Jefe del Depto. de Informática y Bioestadística rpe1531 at pasteur.fmed.uaslp.mx
Facultad de Medicine                            Tel: 48 26-23-45 ext. 232
Universidad Autónoma de San Luis Potosí         Fax: 48 28-23-52
Av. V. Carranza 2405
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