Pooling subjects before ICA decomposition avoids biased between-group network comparisons

Evidence

Often the decomposition of the data into independent component is done by performing two (or more) separate ICA analyses on two (or more) groups (see e.g. Schmidt et al. 2013 ). This leads to a difficult interpretation since it is then unclear whether group differences represent (true) differences between subject groups, or whether the data-decomposition was slightly different (biases) for the two groups. In contrast, we adopted a strategy where the data is pooled over all participants and data-modalities (restingand fixed-state data). In this way, the data-decomposition is not determined in a potentially different way for both groups, leaving out the necessity of post-ICA matching of corresponding component maps. — Dijk, Pim van, Physiology, Psychoacoustics and…, 2703

Categorization

• DEFINE: A clear methodological distinction: separate per-group ICA vs pooled ICA affects the validity of group comparisons.