A jolly history of the experimental in economics and social science, Randomistas: How radical researchers are changing our world by Andrew Leigh, is a good general introduction to the RCT method for readers unfamiliar with it. The book starts with a 1747 experiment to find a cure for scurvy, an affliction causing mass death and illness among sailors. Medicine was of course a pioneering arena for the experimental method as applied to ourselves. Subsequent chapters roam through psychology and education to more recent applications in ‘nudge’ policies, A/B testing by digital companies, and of course the famous ‘randomistas’ (so named by Angus Deaton) working in development economics.
The book is a jolly description of experimental discoveries in these domains ever since the scurvy experiment of ship’s surgeon James Lind. It notes that the randomista methods have their critics but doesn’t linger on the methodological debate. The author (an Australian MP and former economics professor), though well-informed and citing the extensive literature, is clearly an ardent enthusiast.
The final chapter, ‘Building A Better Feedback Loop’, indeed makes a strong case that it would make for better outcomes if policymakers and politicians were able to change course on the basis of evidence. One of the practical advantages of RCTs is perhaps that they leave open the decision – they can be described as pilot schemes in the policy context. There is far too little evaluation in policymaking – it can be too embarrassing, the decisions are water under the bridge – so setting up an evaluation in advance by design, as it were, is attractive.
Experimental approaches are surely welcome as one more addition to the toolbox of policy evaluation, more useful in some contexts than others, vulnerable (like all empirical methods) to not being well carried out or interpreted. They can easily become a means of manipulating people – as in the behavioural testing done by online marketers – so should always be deployed with caution in the world of policy and politics. After all, people are wising up to the testing methods used by Facebook, Amazon, etc and not necessarily liking them. So I would be less of a randomista enthusiast than Andrew Leigh; other methods of evaluation are available.
Still, this is a very lively, well written book with lots of examples (some familiar like the Perry Preschool trial, others not). Experimental approaches are being more widely used, not least because of the spread of ‘nudge’ units (as pioneered by the UK’s Behavioural lnsights Team) around the world.
And its basic point is essential: the scientific method should apply to the study of human society just as much as to the natural world. The more tools available, the better.