Introducing Test+Build – a new tool to help you run your own randomised controlled trial.

Michael Sanders, Miranda Jackman and Martin Sweeney at Behavioural Insights Team: “Work in fraud, error, and debt, and especially tax compliance and collection, has always been a core part of what the Behavioural Insights Team (BIT) does. One of our favourite pieces of work is still that first HMRC trial that told taxpayers with outstanding debts that ‘nine out of ten people pay their tax on time.’ That trial significantly increased the rate at which people paid their taxes, bringing forward £3 million in tax debt. It’s a result that has since been replicated worldwide….

Though all these trials have been in very different contexts and situations, they all employ similar insights and involve running trials to test which letter is most effective. And this got us thinking. Could we build a tool that would enable us to automate lots of the process, while also helping organisations to build their own capabilities? We are pleased to say that the answer is, yes.


Our new tool is called Test+Build, and it aims to hugely increase the use of behavioural science in tax collection by helping people design and run their own randomised controlled trials. Test+Build does this by guiding users through the four stages of BIT’s TEST methodology – Target, Explore, Solution and Trial – and provides them with guides, case studies and videos developed by the team that relate to compliance and enforcement. Test+Build also brings in support from BIT researchers to offer advice, conduct randomisations, and analyse and interpret the results. It provides organisations with the tools to run their own trials, and in doing so, increases the organisation’s level of expertise for implementing them in the future.

By letting users work through the process themselves, with support from BIT researchers at key points along the way, we’ve significantly reduced the cost to organisations of running a BIT trial – by about 50 per cent. Of course, the all-important question for us is – as always – does it work?…(More)