Power-matching
Subjects were sub-selected from each age group, such that the distribution of change in band power within the groups were matched. We first binned the subjects within each age group with respect to the power and computed the greatest common distribution. Within each power bin, subjects were randomly selected from the group with more subjects, to match the subjects in the other group. Ultimately, the subjects in each bin were adjusted to arrive at the common distribution for the two age groups. This procedure eliminates the dependence of power on the effect under study, i.e., the FC (Churchland et al. , 2010).
Since each iteration produced a different subset of subjects, the resultant p-value (obtained using Kruskal-Wallis Test) varied with each iteration. We executed this random sampling 50 times and chose a representative iteration (Figure 3) that represented the overall distribution of results (p-values). Specifically, we used the iteration with p-value near the median of the distribution for both left and right electrode groups.
Power matching for MCI vs. healthy comparison was done on a single subject basis. The subject among the age (within ±1 yr gap) and gender matched controls with minimal separation in change in power from the case subject was selected for each case.