[R] help about 2 way anova and tukey test
Sarti Maurizio
sarti.m at irea.cnr.it
Thu May 24 15:04:51 CEST 2007
Dears members of R list,
I have a technical question about conducting 2 way analysis of the variance
(ANOVA) for repeated measures followed tukey test using R.
my data are:
There were 3 subj in all and 3 repeated measures for every time and therapy
therapy = a,b,c
time = t1,t2,t3
subj = 1,2,3
subj therapy t0 t1 t2
1 a 80.5 82.2 54.23
2 a 84.9 85.6 56.83
3 a 81.5 81.4 54.30
1 b 83.8 95.2 59.67
2 b 83.3 94.3 59.20
3 b 86 91.5 59.17
1 c 80.7 80.2 53.63
2 c 89.4 80.1 56.50
3 c 91.8 86.4 59.40
the code that I use is:
rm(list=ls(all=TRUE))
dati<- read.table("dati.txt", T)
attach(dati)
subj<- c( 1: 9, 1: 9,1:9)
therapy<- factor( c( rep(" a", 3), rep(" b", 3), rep(" c", 3),
rep(" a", 3), rep(" b", 3), rep(" c", 3),
rep(" a",3), rep(" b", 3), rep(" c", 3)))
time<- factor( c( rep(" t0", 9), rep(" t1", 9),rep(" t2", 9)))
weight<- c( t0,t1,t2)
time <- factor( time)
therapy <- factor( therapy)
subj <- factor( subj)
summary( fm1<-aov( weight~time*therapy))
fm1Tukey=TukeyHSD(fm1,"therapy",ordered = TRUE) ; fm1Tukey
fm1Tukey=TukeyHSD(fm1,"time",ordered = TRUE) ; fm1Tukey
fm1Tukey=TukeyHSD(fm1,"time:therapy",ordered = TRUE) ; fm1Tukey
My question is - is that the correct way to do it??
Very much obliged for your kind response
Maurizio
******************************************************************************
Maurizio Sarti, PhD
IREA - CNR
via Diocleziano,328 I-80124 Napoli (Italy)
tel:+39-(0)81-5707999-(0)81-5704945 fax:+39-(0)81-5705734
cell:+39-3204397891
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e-mail: sarti.m a irea.cnr.it website: http://www.irea.cnr.it
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