Many social, educational and economic policies are the modern equivalent of Dr Spock’s advice that babies should sleep face down: well-meaning, authoritative – and wrong. No doubt it would be awkward to see the wisdom of experts punctured and the pet policies of politicians discredited on a regular basis. But if politicians really cared about those they represent, they would insist on more randomised trials and more systematic reviews of what works. Honest policy mistakes, quickly reversed, should embarrass nobody. As voters, we should demand more such mistakes.

Tim Harford (The Undercover Economist) on the lack of proper experimental attitudes in what are, essentially, government experiments.