The wheels of language run so smoothly that one rarely bothers to stop and think about all the resourcefulness and expertise that must have gone into making it tick.

In a recent article, Roberta Piermartini and Robert Teh, two economists at the WTO, urge modellers to "demystify" their creations, making it clear to their audience what makes their models tick.

Well, let's not waste time making the line operators write down the measurements that they read; they take more measurements than what's required, so an OK or a tick is more than enough.