The bestselling economics book, Freakonomics by Steven Levitt and Stephen Dubner has a section on the quickly diminishing marginal returns of election campaign spending. In this, they disprove the widely-held truism that 'money buys elections'. First they admit that there is a correlation between money and politics: those candidates or parties that spend the most often win. But they dispute the commonly held assumption that the spending causes the win. Instead they point out that anticipated win - or possible win - will often attract the campaign money. When candidates obtain large amounts of money it is usually because they are seen to be the best candidate or the one mostly likely to win. Based on Levitt's study of campaign spending by the same candidates against the same competitors over decades of US congressional elections, it was found that 'the amount of money spent by the candidates hardly matters at all. A winning candidate can cut his spending in half and lose only 1% of the vote. Meanwhile, a losing candidate who doubles his spending can expect to shift the vote in his favor by only that same 1%'. The Freakonomics authors conclude that campaign spending has a very small impact on election outcomes, regardless of who does the spending.