Dear experts,
I want to make a group analysis using a fixed effect model. Because of
the small sample sizes (7 and 4 subjects) the random effect toolkit is
not adequate (very small df). So I put all subjects in one big model and
weighted the contrasts (11/2 = 5.5, contrast weights 1.4 and 0.8 for the
individual subjects in the two groups respectively, the contrast vector
is simplified 1.4 1.4 ... -0.8 -0.8 ...). Is this is a valid approach
or is their a correction for different dfs necessary and how can I
perfom that ? What is the best way to make group comparisons
(especially with unequal sample sizes) using the fixed effect model (I
know that I have only the scan to scan variability and not the variance
between subject) ?
TIA
Ralf
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