[R] aov() and lme()
Jan Wiener
jan.wiener at tuebingen.mpg.de
Thu Oct 27 13:14:59 CEST 2005
Sorry for reposting, but even after extensive search I still did not
find any answers.
using:
summary(aov(pointErrorAbs~noOfSegments*turnAngle+Error(subj/(noOfSegments+turnAngle)),
data=anovaAllData ))
with subj being a random factor and noOfSegments and turnAngle being
fixed factors, I get the following results:
----------------------------------------------
Error: subj
Df Sum Sq Mean Sq F value Pr(>F)
Residuals 17 246606 14506
Error: subj:noOfSegments
Df Sum Sq Mean Sq F value Pr(>F)
noOfSegments 3 7806.6 2602.2 5.3257 0.002864 **
Residuals 51 24919.4 488.6
---
Signif. codes: 0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
Error: subj:turnAngle
Df Sum Sq Mean Sq F value Pr(>F)
turnAngle 5 14660 2932 3.1707 0.01131 *
Residuals 85 78600 925
---
Signif. codes: 0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
Error: Within
Df Sum Sq Mean Sq F value Pr(>F)
noOfSegments:turnAngle 15 19637 1309 2.9135 0.0001711 ***
Residuals 687 308687 449
---
Signif. codes: 0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
------------------------------------------------------------------
all is fine, and I get exactly the same results as with unix anova.
No I trying to fit the same data with lme and using the following call:
anova(lme(fixed=pointErrorAbs~noOfSegments*turnAngle, random=~1|subj,
data=anovaAllData))
Unfortunately the results are 'really' different from the aov()
procedure (I guess I have the call wrong):
----------------------------------------------------
(Intercept) 1 823 42.10888 <.0001
noOfSegments 3 823 5.19549 0.0015
turnAngle 5 823 5.85379 <.0001
noOfSegments:turnAngle 15 823 2.61373 0.0007
----------------------------------------------------
I, however, need a comparable method for lme(), because in a different
data set I have single empty cells and can therefore not use aov().
does anyone know how to fit with lme() to obtain the same results (for
this balanced data set) as with aov().
Thanks in advance,
Jan
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