[R] Tukey HSD with repeated measure ANOVA
Daniel Malter
daniel at umd.edu
Wed Jul 13 23:03:41 CEST 2011
Try TukeyHSD(anova). TukeyHSD is implemented in the base package, i.e., ready
to use with the base installation of R. Also, the TukeyHSD for the
interaction term should have a colon ":" not a "*". The "which" argument in
TukeyHSD() must be identical to the name of the coefficient in the summary
table.
See the example below:
Thesis<-sample(c(1:3),300,replace=T)
Days<-sampe(c(1:2),300,replace=T)
Days<-sample(c(1:2),300,replace=T)
e=rnorm(300)
y<-Thesis+Days+Thesis*Days+e
my.anova<-aov(y~factor(Thesis)*factor(Days))
summary(my.anova)
TukeyHSD(my.anova)
TukeyHSD(my.anova,which="factor(Thesis)*factor(Days)") #fails
TukeyHSD(my.anova,which="factor(Thesis):factor(Days)") #works
HTH,
Daniel
Roberto wrote:
>
> Hi,
> I need to determinate HSD value from a matrix like that
>
> Thesis Days A1
> Cx 0 66.07
> Cx 0 60.24
> Cx 0 42.86
> Tw 0 66.07
> Tw 0 60.24
> Tw 0 42.86
> Aa 0 66.07
> Aa 0 60.24
> Aa 0 42.86
> Qe 0 66.07
> Qe 0 60.24
> Qe 0 42.86
> Cx 56 310.86
> Cx 56 223.17
> Cx 56 186.77
> Tw 56 149.42
> Tw 56 127.75
> Tw 56 138.59
> Aa 56 130.24
> Aa 56 214.83
> Aa 56 137.95
> Qe 56 186.64
> Qe 56 189.09
> Qe 56 187.87
>
> this is my script
>
> require(agricolae)
> file <- "A1.txt"
> data_table <- read.table(file, header=T, row.names=NULL)
>
> attach(data_table)
> anova <- aov(A1 ~ factor(Thesis)*factor(Days))
> detach(data_table)
>
> first of all, I need to know if my script has conceptual errors
>
> secondly, I need to calculate HSD between Thesis:Days means
> I try with Tukey.test command from agricolae package, but it do not work
> I can use only these commands
>
> Tukey.test(anova, "Thesis")
> Tukey.test(anova, "Days")
>
> but not
>
> Tukey.test(anova, "Thesis*Days")
>
> how can I do?
>
> my apologies for the banal questions, but I'm taking the first steps in
> statistical computing
>
> Thanks,
> Roberto
>
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