Instead of placing big bets on assumptions about ideas when they are first proposed, policies need to be reviewed and improved throughout their development via a process of test and learn. This playbook explains what test and learn is, how to use it throughout the policy cycle and provides a methods toolkit that can be deployed at each stage.

Test and learn is an iterative approach to public policy and service development. Conventional policymaking typically uses a step-by-step process called “waterfall” where most of the big choices are made upfront. Yet we know least about how to solve a problem at the beginning.

Instead, government should adopt an iterative approach, starting small, testing critical assumptions early and often through rapid learning cycles, and learning from real-world delivery. Robust evidence informs early design, and appropriate evaluation methods assess whether optimised policies and programmes are achieving results. Insights from local experiments and frontline practice guide wider policy and service rollout. As these are scaled, they should be refined through ongoing test-and-learn cycles, ensuring they remain effective, responsive, and grounded in evidence.

Importantly, test and learn should not be understood as only involving a series of small design experiments that can replace rigorous evaluation. Done well, test and learn brings together iterative development and robust evaluation to deliver on long-term outcomes such as the UK Government’s mission goals. 

There are already encouraging examples of test and learn within the UK government. In the mid-2010s the huge Universal Credit scheme, initially developed using traditional waterfall methods, faced serious implementation challenges. A strategic reset that applied test and learn saved the programme. However, applying this method to policy tends to be the exception rather than the rule. 

An ambitious test and learn programme would build an R&D ecosystem for the UK government, using test and learn approaches to de-risk new complex policies, optimise existing services, and design and scale new public programmes. Iterative ‘learning loops’ would test critical assumptions early and provide feedback to ensure data and evidence regularly inform policy design and implementation. 

To achieve this goal, the UK government can draw on the experiences with test and learn from other sectors. At Nesta and BIT, for example, we embed test and lean in how we work towards our missions and with our partners. For example, we used test and learn techniques like iterative prototyping in our Visit a Heat Pump scheme and rapid, affordable nimble trials in the evaluation of the National Tutoring Programme.

The UK government already has many of the building blocks required to work in a test and learn way. This includes the joint Cabinet Office-Treasury Evaluation Task Force, £100m funding for place-based test and learn initiatives, and the essential capabilities required to work in a test and learn way such as designers, data scientists and evaluators. 

However, embedding test and learn at scale will require the government to change the way it operates. This will require: 

• Outcome-based accountability – teams tasked with delivering outcomes not policies, activities or outputs. This will require firmly defining goals while remaining flexible in the ways to reach them.
• A shift to agile ways of programme design and delivery – away from linear "waterfall" approaches where everything is decided upfront; agile is not new but remains the exception in government.
• Changes to funding rules – funding that increases when risk decreases as more is learnt about programmes alongside more locally controlled funding.
• Flexible procurement mechanisms – enabling more flexible contracting with more decision points part way through delivery.
• New units of delivery such as multi-disciplinary teams combining policy, delivery, operations, service design, innovation and evaluation expertise.
• Improved data infrastructure and digital capabilities at central and local government and improved access, linkage and use of data.
• More local capacity and new capabilities to innovate, monitor, evaluate and iteratively adapt.
• Legislative frameworks that allow the creation of “sandboxes” for local experimentation.
• Working in the open – transparently sharing insights, successes, and failures. 

Test and learn approaches can be used for almost any policy, service or programme. A good place to start is with those that have:

1. Available data – particularly on leading indicators that signal the likelihood of success.
2. Tractability – where we have a basic understanding of the problem and mechanisms.
3. Established provider(s) – able to deliver relevant services.
4. Delivery infrastructure to scale – to double down on opportunities with the potential for growth.
5. Recognition and appetite to solve the problem – especially by local partners where most of the delivery capacity sits.

While government may want to start applying test and learn to the most tractable problems, the technique is well placed to tackle knottier challenges like the transition to net zero as test and learn can help de-risk new complex policy and handle the associated uncertainty and evidence gaps.

At a time when public services face mounting pressures and public finances are constrained, test and learn is critical to enabling the government to cost-effectively deliver on its five missions and the Plan for Change. This approach would de-risk policy and funding decisions, help navigate the uncertainties of addressing complex problems, and accelerate the delivery of impactful solutions. 

The UK Government now has a unique opportunity to try a different way of doing things. If the right choices are made about test and learn today then by the end of the next Parliament, UK public services will be transformed for the benefit of the British people.