Need central bankers be trained economists? The US does not think so. Donald Kohn's announcement that he is leaving the Federal Reserve in June leaves Ben Bernanke as the only economics specialist on the board of governors. Likewise, in Australia more than half the committee that jacked up interest rates last week were never forced to read Keynes in the original. Not so at the European Central Bank, where doctorates in economics are almost de rigueur. And all but one of the Bank of England's monetary policy committee were formally educated in the dismal science. Are CVs, therefore, irrelevant? After all, during the financial crisis central banks stacked with academics as well as those with mixed boards were praised and criticised alike. But surely not everyone qualifies. Markets would certainly not tolerate policymakers at the Bank of Canada, say, being made up entirely of ice hockey players – because the holy grail of central banking is credibility.

This is a much debated topic in monetary policy economics. Generally, credibility is thought to be a good thing. If policymakers are credible, they can keep inflation low without having to resort to higher interest rates – merely knowing inflation will not be tolerated is enough to keep expectations in check. The trouble is that credibility is hard to measure (academics sometimes resort to using central bank independence as a rough proxy) and its benefits are inconclusive.