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2008 Jul 20
0
Off topic: SS formulae for 3-way repeated measure anova (for when aov() fails)
...uld not use AOV to perform an anova on my large
data set, I'm now trying to code the analysis "by hand" so to speak.
However, as demonstrated below, when comparing my attempt to aov()
using a smaller data set, I seem to betray some sort of
misunderstanding when I try to compute SSerr for the first interaction.
Obviously I have missed something and although I have looked around
for the explicit SSerr formulas for this design (my work thus far was
extrapolated from understanding of a 2-way design), I can't seem to
find any.
Any help would be much obliged.
N = 20
levs...
2005 Sep 08
0
Effect of data set size on calculation
...Calculate class-to-class variance
#
for (j in 1:maxc) {
cmean <- rbind(cmean,mean(mat[((j-1)*nreps+1):((j-1)*nreps+nreps),]))
}
for (j in 1:ncol(mat)) {
cmean[,j] <- cmean[,j]-totmean[j]
}
cmean <- (cmean)^2*nreps
for (i in 1:ncol(mat)) {
sscl[i] <- sum(cmean[,i])
}
#
# sserr <- sstot-sscl
#
ratios <- (sscl/dfcl)/((sstot-sscl)/dferr)
I have tested the above on a small data set (based on average on the
second dimension) and produced a result which was meaningful. However,
when I analyse data with both dimensions (larger dataset), the analysis
is not successfu...