Hi All,
I am illustrating a simple, two-way ANOVA using the
following data and I'm
having difficulty in expressing the predicted values
succinctly in R.
X<- data.frame(read.table(textConnection("
Machine.1 Machine.2 Machine.3
53 61 51
47 55 51
46 52 49
50 58 54
49 54 50"
), header=TRUE))
rownames(X)<- paste("Operator.", 1:nrow(X), sep="")
print(X)
# I'd like to know if there is a more elegant way to
calculate the residuals
# than the following, which seems to be rather a kludge.
If you care to read
# the code you'll see what I mean.
machine.adjustment<- colMeans(X) - mean(mean(X)) #
length(machine.adjustment)==3
operator.adjustment<- rowMeans(X) - mean(mean(X)) #
length(operator.adjustment)==5
X.predicted<- numeric(0)
for (j in 1:ncol(X))
{
new.col<- mean(mean(X)) + operator.adjustment +
machine.adjustment[j]
X.predicted<- cbind(X.predicted, new.col)
}
print(X.predicted)
X.residual<- X - X.predicted
SS.E<- sum( X.residual^2 )
It seems like there ought to be some way of doing that a
little bit cleaner ...
Thanks,
Jack.
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