At Nesta we take impact very seriously. For the kind of work we do, measuring it is rarely straightforward. It’s complex, messy and full of trade-offs. But it’s also deeply valuable in helping us understand the value of what we’re doing and making smarter choices about where to focus our energy and resources. Here we explain our approach to impact measurement, how we developed our framework for assessing it and how it supports better decision-making across our work.

Our framework uses three layers of information to give insights into progress, portfolio alignment, and direct project impact. 

1. Progress indicators 

At the top layer, we ask: are we seeing change in the world? To assess progress, we track each mission’s progress indicators - metrics showing whether we’re on track to hit key milestones by 2027. For example, under our sustainable future mission we are tracking: 

• the number of low-carbon heating installations per year
• the average lifetime cost of heat pumps versus gas boilers
• the number of active heat pump installers. 

These indicators show whether our work is on track and support high-level decisions about where to focus our efforts.

2. Portfolio

To see if our current work is bringing us closer to mission goals, we take a portfolio view of our work, test our assumptions and capture learning. We do this in two ways: 

A) Live questions - Strategic learning questions that surface the uncertainty we’re grappling with and guide decisions about the work we do. 

Examples include: 

• What is the role of GLP-1s for reducing obesity? 
• Which parts of the heat pump consumer journey cause the most friction or drop-off? 
• How can we increase the engagement of parents from low-income households in suitable evidence-based parenting programmes? 

B) Theory-based evaluation (TBE) - an approach that explores how and why a programme works by testing its underlying theory of change and gathering evidence to see whether each step holds true in practice.

A light-touch version of TBE is applied to selected mission ’areas of focus’ (AoF) twice a year. TBE helps link project activities to AoF objectives, develop claims about contribution, and test whether our assumptions about change hold true.

For example, in our healthy life mission, we looked at projects contributing to obesity solutions, including our blueprint for halving obesity by 2030 and our work on industry targets, examining the evidence relating to whether the work we are doing is actually providing the government with impactful policy solutions that could halve obesity if implemented.

Together, live questions and TBE help us decide what to dial up, dial down, or do next to move closer to our mission goals.

3. Case studies

At the project layer, we focus on direct, measurable impact. We showcase flagship projects where evidence has been gathered, including robust evaluations, return on investment calculations, and promising early findings. Here we ask, ‘what measurable impact are we having?’ allowing us to rigorously evaluate, attribute and quantify a portion of our impact.

Equally important as the information we generate is how it’s used. For us, this means ensuring the insights are meaningful and available at the right moments - whether that’s a project lead deciding how to allocate resources within a project, or our executive team considering a fundamental shift in the focus of our mission.

We measure impact for two main reasons: 

• Accountability and transparency - As an endowed charity, we have a responsibility to show how we use our resources. By working openly, sharing both successes and challenges, we hold ourselves to account and contribute to wider learning in the sector. 
• Better decision-making - Good insights help us decide when to double down, adapt, or step away. They support everyone, from mission teams to our board of trustees, to make choices that maximise impact.

We developed an initial impact framework in 2022 and used it over 18 months. While it gave us a strong foundation, when we reviewed it we concluded that it didn’t fully support decision-making or give a complete picture of progress. Along the way, we’ve learned key lessons that have shaped our current framework: 

1. Build on what exists

Connect to routines that already work, draw on the expertise of those closest to the work, and link to other processes that set and review strategy, rather than treating impact as a separate exercise. 

2. Measure what matters

Focus on the outcomes and progress that really tell us if we’re on track. We designed the framework around the people who use it - trustees, execs, and project teams - so it answers the questions they need to make decisions.

3. Make it useful

Embed the framework into day-to-day practices so it actively informs decisions, rather than sitting on the shelf or becoming another reporting exercise that teams have to retrofit.

These lessons remind us that building a framework is not a one-off task, but an ongoing journey, with each cycle bringing us closer to the answer.

Designing a framework that works in practice means balancing tensions: 

• Rigour vs focus - Measuring everything thoroughly can be slow and overwhelming, but doing too little risks missing important outcomes or drawing misleading conclusions. 
• Engagement vs time - Teams need to be involved in producing and reflecting on insights, but this takes time away from delivery. 
• Simplicity vs nuance - Simple metrics are easy to communicate, but risk losing important complexity.

We believe an impact framework should constantly evolve. We are committed to refining both the information we collect and the routines we use to make sense of it, adapting as we learn.

That means:

• refining - continuing to improve as we learn what works
• adapting - adjusting to shifts in context, strategy, and missions
• sustaining momentum - making sure impact measurement stays part of everyday conversations and decisions, not just an occasional exercise.

If you have comments or questions about our framework we would love to hear from you. You can get in touch by contacting [email protected].