SIXTEEN centuries ago the Roman Emperor Theodosius branded the Olympic games pagan and banned them. Some Britons are beginning to think that he was a man of sound views. They resent paying for the games and dread the traffic jams. This week the Sun, a British tabloid, complained of “road chaos as athletes arrive”, a “security shambles” and “as for that bloody rain…”—which, admittedly, is not directly attributable to the games, but has to be blamed on something.

Part of the reason that people get grumpy about the games is inflated expectations: the Olympics are always mis-sold. First, host governments say that the economic benefits of the games will greatly outweigh their costs. Second, they claim that the games will inspire people to exercise more. Third, they predict intangible benefits from being in the global spotlight for a couple of weeks. The first two claims are rubbish; the third does not apply to London.

David Cameron, Britain’s prime minister, promises a bonanza of £13 billion ($20 billion); but the games rarely make money for their hosts. The firms that win contracts are happy, as are the sponsors (see article). The Olympic bureaucracy sucks in billions from broadcasters. But the host nation is not so lucky: 100% of Olympiads since 1960 have seen cost overruns. The average overspend, at 179%, is worse than any other kind of megaproject, including dams. London is even worse: the government’s budget for the games went up from an original estimate of £2.4 billion in 2005 to £9.3 billion now.

Estimates of benefits, alas, are usually too rosy. They tend to overlook extra costs, such as security, that taxpayers bear. They fail to recognise that, although many tourists will come to watch the games, many will also stay away to avoid the crush (see article). And they fail to account properly for opportunity costs. Building an Olympic Park is an expensive way of sprucing up a run-down part of London. That Velodrome is grand, but who will use it when the Olympians are gone?

The evidence that the games make populations healthier is also scant. Britons and others could certainly do with more exercise (see article). But if watching all that running and jumping makes them jump up and run to the gym, the effect is too small to detect. After the 2000 games in Sydney, Australians were slightly more likely to take part in seven Olympic sports, but slightly less likely to take part in nine.

Games and happiness

There may be intangible benefits to being an Olympic city. In 1987, faced with mass protests calling for democracy, South Korea’s ruling generals could have given the order to open fire, but that would have ruined the 1988 Seoul Olympics. Instead they gave in to the protesters’ demands. The Olympic spotlight thus helped South Korea become a democracy: no small boon. That did not, however, work for China, where the 2008 games were accompanied by a political crackdown. As for host countries that already have pluralistic politics, the benefits are not obvious. A study by Stefan Szymanski and Georgios Kavetsos found that hosting a big sporting event makes people significantly happier—so long as that event is the football World Cup. For the Olympics, the “hedonic effect” was insignificant.

For Londoners, however, the games will have an upside. Because many of the events are in the city centre, the authorities fear that the transport system may jam up. Their principal strategy for getting the visitors to the games is to tell the locals to stay off the trains and the streets. The locals seem happy to comply, and many employers have agreed that staff should “work from home”. The sofa, and two weeks of watching the world’s best athletes, beckon.