The assumption that patients across diagnostic groups respond differently to non-invasive brain stimulation, including transcranial magnetic stimulation (TMS) and transcranial direct current stimulation (tDCS), is based largely on the observation from randomized controlled trials (RCT). This observation motivates the efforts to personalized medicine. However, these efforts might actually be based on a misguided assumption to begin with. In this project, we test this assumption by comparing the variability in the real stimulation group to the variability in the sham group of RCTs.