Cameron Crise, an analyst at Warburg Dillon Read, has tried to do this by making use of equity risk premiums.

ECONOMIST: Test-driving a new model

And the euro will recover against the dollar, argues Mr Crise, only if the gap between equity risk premiums in America and Europe is closed.

ECONOMIST: Test-driving a new model

However, Mr Crise suggests that it could be viewed in the same way as varying risk premiums on different countries' government bonds, meaning that it reflects uncertainty about the relative attractiveness of a country's equity markets.

ECONOMIST: Test-driving a new model