I'm facing the issue that I conducted a fMRI-experiment and have to
exclude 3 sessions due to artefacts (in total 15 per 2 groups). I
would like to calculate a 2x2 factorial design (with repeated
measurement). Due to the exclusion I end up with an unbalanced design
in the meaning that the sample size in the 4 different groups are not
the same. I know from SPSS that unbalanced designs have to be treated
specially. How SPM can deal with that issue? Is there another
possibility than casewise deletion?
Any comments and ideas are very welcome!