LOOK only at unemployment and inflation, says Peter Conti-Brown, a historian of the Federal Reserve, and Janet Yellen is the Fed’s most successful boss of all time. The second indicator may be below target, but that is a blip compared with the recessions most Fed chairmen have endured. So it is perhaps not surprising that President Donald Trump is openly considering retaining Ms Yellen, a Democrat installed by Barack Obama, after her term ends in February 2018. Nor by historical standards is it odd: the Fed’s past three leaders were all reappointed by presidents from the other party. Yet Ms Yellen, whom Mr Trump criticised on the campaign trail, is not the leading candidate. PredictIt, a betting site, gives her a 28% chance of staying put. In front of her, with a 36% chance of appointment, is someone else Mr Trump is publicly weighing up: Gary Cohn (on the left above).