I don’t normally hold with the traditional New Year’s resolution of quitting some objectionable habit – even though my favourite economist, Thomas Schelling, has written very thoughtfully on the subject. (Schelling, a brilliant game theorist and long-time smoker, used a variety of game theoretic tricks to outwit a formidable opponent – his addicted self.)

But as 2011 drew to a close, I had been wondering about my addiction to Twitter, the service that allows users to publish online short messages – grumbles, aphorisms and most often, links to recommended articles. Other users can choose to whose messages they will subscribe and unlike on fully-fledged social networks, such as Facebook, this is not necessarily a reciprocal relationship. (Facebook users have friends; Twitter users follow and have followers.) My Twitter habit has the pernicious consequence of being rather time-consuming – but it has plenty of benefits too. Should I quit? Cut down? Or should I resolve only to stop feeling guilty?

Part of the problem, I realised, is the difficulty of measuring the costs and benefits of the habit. Imagine my curiosity, then, when I noticed that the economist Justin Wolfers – a self-described Twitter cynic – had joined the club and was running an experiment to test how Twitter was affecting his productivity.