If only they’d studied the tweets (Image: Andy Rain/EPA/Corbis)

In the time it takes you to read this sentence, more than a thousand tweets will have been twittered and dozens of blogs posted. Much of their content will be ephemeral fluff: personal gripes and tittle-tattle interesting to no one but the parties concerned. Yet despite this, it is possible to use that torrent of information to make predictions about social and economic trends that affect us all.

Interest in the idea of analysing web data to make predictions took off around a year ago, when researchers at Google used the …