One unusual thing about Powell's appointment is that he is a lawyer, not an economist. From Yellen going back to Alan Greenspan, who started as chair in 1987, all Fed chairs have held a Ph.D. in economics. Alan Blinder, an economist at Princeton, has said that a doctorate has become more or less a prerequisite of the job—without one, he told Harvard Business Review, "the Fed's staff will run technical rings around you." While that remains to be seen, it is true that there are over 300 Ph.D. economists on the Fed's staff, and Powell could end up needing to lean on their expertise more than a Fed chair with a doctorate in economics might.