Group level analysis, conditions differ over runs

Hi guys,

My dataset consist of 1 group and one session per subject. Session consists of 6 runs.
There are 6 different conditions: A, B, C, D, AB, CD

My problem is: this conditions are represented in pairs per run e.g.

run-01: condition A and B
run-02 condition C and D
run-03 condition AB and CD


run-01: condition AB and CD
run-02 condition A and B
run-03 condition C and D

Therefore some conditions are never represented in the same run.

Is it possible to do a group level analysis and to estimate contrasts for A > AB, or D > CD?

I mean, the effect/activations are probably influenced by the run itself, aren’t they?



I was referred to the FEAT Users Guide for my similar question. I’m still working my way through it.

I have read the FSL users guide and the SPM12 manual before posting this question. My question is more about statistics. So, I mean, I know that it is technically possible, but I am not sure if it does make any sense.