The Wiki Man | 8 March 2008

As you probably know (to your cost), Amazon purchases above a certain value incur no delivery charge. This offer works because so many people buy extra books to lift their order above the free-postage threshold. Predictably, in every country in which the retailer has launched the scheme, there has been an immediate and sustained uplift in sales. Except France. There the introduction of the offer had almost no effect. Yet this isn’t another case of l’exception française: in France, it emerged, the scheme was minutely different. Rather than offering free postage, as elsewhere, the company charged a trivial amount (around 10p). This seemingly irrelevant detail was the problem: once amazon.fr removed this charge, making the offer truly free, it worked as well as anywhere else. ‘Free’, it turns out, is not merely an arithmetic extension of ‘cheap’, it is something else entirely.

I learnt this from a new book called Predictably Irrational by MIT’s Dan Ariely which arrived from Amazon this week (along with a second book I didn’t really want).