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07 March 2024

Can 'nudges' work at scale?

Michael Sanders and Vanessa Hirneis

Our new project will deliver behavioural science interventions to as many people as possible

Illustration of a man being pushed from behind by an oversized hand

For the last decade and a half, behavioural science has taken the worlds of business and public policy by storm. According to the World Bank, well over 100 countries now have behavioural insights teams, or “nudge units” as they are often called, embedded within their governments.

The promise of this endeavour has been that low-cost interventions based on behavioural science and a more realistic model of human behaviour can make a meaningful difference to a range of citizen behaviours in a way that lets people live healthier, wealthier, and happier lives, to crib from the subtitle of Nudge, by Richard Thaler and Cass Sunstein, the book which inspired all of these units.

To a great extent, the movement has done well. Pioneering the routine use of randomised trials, there is strong evidence of the effectiveness of these behavioural interventions across a range of domains, from tax and education, to energy and exercise. Recent meta analyses show that the effects are small – often much smaller than we might anticipate if we relied on the academic literature alone – but meaningful and reliable. The movement has much to be proud of.

However, we must also recognise the limitations of what has been done, and nowhere is this more evident than in the problem of scaling. A study by Elizabeth Linos and Stefano Dellavigna found that when effective nudges were identified by field trials with partners, only in a minority of cases did those interventions persist beyond the end of the trial. Without continuation and scaling, the promise of all of this work will fall sadly short. Part of the problem is that scaling is nobody’s job. Government officials are always moving on to the next challenge, consultants to the next contract, and academics to the next paper.

We have chosen to make it our problem, and that’s why we’re excited to launch a new project focused exclusively on taking interesting, evidence-based interventions to scale. The project, which is in partnership with the social purpose consultancy Exogeneity, will focus in the first year on developing partnerships and taking a handful of interventions to as large a scale as we can manage. More information can be found elsewhere, but the projects are focused on:

  • Boosting attendance of selective universities by young people from less fortunate backgrounds (in partnership with TASO).
  • Letting students across the country know about the financial support available from universities, in partnership with the Sixth Form Colleges Association; the Schools, Students and Teachers Network; and the National Association of Virtual Schools Heads.
  • Helping improve the morale of people working in social care in Wales in partnership with Social Care Wales.

We’ll be adding more to this list as we go, but for now, our focus is on getting these interventions delivered to and for as many people as we can. We’ll report back on how it goes – so watch this space!


Michael Sanders is Professor of Public Policy and Director of the Experimental Government Team at the Policy Institute, King’s College London.

Vanessa Hirneis is a Researcher at the Policy Institute, King’s College London.