Hello
I have a question on how to perform a Duncan test after I set a model like this
(see below).
The data consist of a dependent variable (PHt) and two dependent variables
(REGION (3 levels) AND MANAGEMENT (3 levels)).
MANAGEMENT
N P S
REGION A 196 196 196
V 196 196 196
H 196 196 196
196 is the number of trees on which PHt was estimated, but we cannot consider
them as repetitions, they are subjects. Therefore, only one repetition per
REGION*MANAGEMENT factor.
I set a two way ANOVA without repetition. Although within
model <-
aov(PHt~REGION*MANAGEMENT+Error(subject_f/(REGION*MANAGEMENT)),data=obsHETf)
Then I try to run a Duncan test for REGION and also for MANAGEMENT. I get this
error message.
Error in as.data.frame.default(x[[i]], optional = TRUE, stringsAsFactors =
stringsAsFactors) :
cannot coerce class "c("aovlist", "listof")" to a data.frame
Is there anyone who could give me a clue on what it is wrong? Maybe it isnot
correct to call for a Duncan.test() for such type of model?
If I fit only the mean (mean of the 196 observations) within each
REGION*MANAGEMENT factor, then Duncan.test() works as expected. The model then
looks as simple as this.
model <- aov(PHt~REGION+MANAGEMENT,data=obsHET)
Thanks in advance.
R.
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