Dear CONN-artists,

Is it reasonable to assume that second level group comparisons of reconstructed ICA maps between groups of unequal sizes may be biased by the estimation of the group level ICA components?

In other words - if 100 subjects (20 patient 80 control) are used to estimate 10 components followed by second level modeling comparing a particular component between subject groups, will observed differences be biased by the number of subjects in each group?

Is there a way (besides splitting your groups) to ensure unequal sample sizes at group ICA estimation does not effect  second level comparisons?