Milgram and Elms conducted interviews with a small sample of fully obedient participants, who scored highly on the F-scale, believing there may be a link between obedience and authoritarian personality. However, this link is merely a correlation between two variables. This makes it impossible to draw the conclusion that authoritarianism causes obedience. It may be that a 'third factor' is involved, for instance, both obedience and authoritarian personality are associated with a lower level of education.