In an EEG study, I am trying to compare the brain networks of 3 motor tasks while functional interactions are measured by 3 estimators coherence (Coh), imaginary part of coherence (iCoh) and partial coherence (pCoh). My results show that for task 1, more connections are achieved by Coh (denser network), for task 2 more connections are achieved by iCoh and for task 3 more connections are achieved by pCoh. Regardless of other steps and methodological considerations of this research, is there any explanation for this behavior of connectivity estimators? Is there any reference regarding this issue?