Just to provide a summary of off-list conversations with Stephen
Fromm, what Donald McLaren had initially posted is what I believe is
correct. I was misinterpreting the split means.
For 4 splits (3, ev = a, b, c) split means and one run mean (ev = d)):
a b c d
1 0 0 1
1 0 0 1
0 1 0 1
0 1 0 1
0 0 1 1
0 0 1 1
0 0 0 1
0 0 0 1
a = s1_mean - s4_mean
b = s2_mean - s4_mean
c = s3_mean - s4_mean
d = s4_mean
so to get the mean for each split:
contrast for s1mean = a+d or 1 0 0 1
contrast for s2mean = a+d or 0 1 0 1
contrast for s3mean = a+d or 0 0 1 1
contrast for s4mean = d or 0 0 0 1
Thanks again to both Stephen Fromm and Donald McLaren.
Cheers,
McKell
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