Perhaps the most consistent predictor of presidential greatness, Messrs. Uscinski and Simon found, is military service. Serving on active duty during both wartime and peacetime, as well as the number of years of service, is associated with higher scores in many domains, including crisis leadership, international relations, and economic management.

Service in the federal government, either the executive or legislature branch, has few apparent effects. It typically matters only in narrower domains. So previous service as a federal administrator is associated, unsurprisingly, with perceived skill as an administrator. And previous service in Congress is associated with higher ratings in terms of relations with Congress.

That said, being an “outsider” is also not typically helpful. Years in public office at various levels (federal, state, local) is not significantly associated with most dimensions of greatness, but when it is, the relationships are almost always positive: experience helps. Moreover, outsiders — those with no federal experience — earn lower ratings on three dimensions.