Ray Fair, an economics professor at Yale, has analysed the impact of several economic variables on voters and shown, perhaps unsurprisingly, that low inflation tends to favour the incumbent party, while rising prices favour the challenger. Similarly, no one will be particularly surprised that high economic growth in the first nine months of an election year is good news for the occupant of the Oval Office. Soggy growth this year goes some way to explaining why a relatively underwhelming Republican challenger is neck and neck with the President in the polls.