
Understanding Impact
How to use your theory of change to develop a measurement and evaluation framework
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Did we make a difference? That’s what every charity wants to know. Answering this question can be tricky. It’s hard to collect reliable data about things that have changed. And even if you can, how do you know it was down to you? Would change have happened anyway?
We’ve written this guide for charities who seek to evaluate their work, or measure their impact. Measuring means using data and evidence, both quantitative and qualitative, to gain useful insights about your charity’s work. It’s about understanding whether your project or service made a difference in people’s lives. If yes, how so? If not, why not?
This guide follows on from our Theory of change in ten steps, which we want you to use as the basis of your measurement framework. We explain how to turn your theory of change into a plan for measurement, the five types of data you will need to pay attention to, and how to prioritise what to measure. Finally, we’ve included seven mini-guides below looking closer at specific aspects of evaluation.
Understanding impact is central to our work at NPC, as one of our core consultancy services for charities and funders. Since our 2014 guidance was published, we’ve helped over a hundred clients understand their impact, with many more charities attending a training event or reading our free resources online. Our new guidance builds upon everything we’ve learnt, and draws on our other NPC papers on this topic. We include new advice on how data should be collected, analysed and used, and discuss what an evidence-based learning culture could look like.
To go deeper, come to one of our training events, or get in touch to arrange bespoke support from our team of charity consultants.
A closer look at evaluation techniques:
1. Quantitative methods
Collecting data from staff and service users, using surveys, online data and social media.
Learn more2. Qualitative data
Hearing from service users about their experience and perceptions in their own words.
Learn more3. Sampling
Concentrating on better data from a small representative group, rather than lots of poor-quality data from lots of people.
Learn more5. Research ethics
Understanding the ethical issues that come up when service users are involved as participants in your research.
Learn more6. Analysing and using data
Making sense of the data you have collected, finding patterns and themes, so you can learn and improve.
Learn more7. Developing a learning culture
Everyone involved in the project should be collecting data, thinking about results and trying to continuously improve.
Learn moreProject team
We are grateful to the Esmée Fairbairn Foundation for their generous support of this work.
Learn more about theory of change

Theory of change in ten steps
This new guide is a ten step handbook to creating a theory of change, built on many years of developing them for charities and funders. It will teach you the basics, our core approach, with the information you need to do any theory of change.

Mechanisms – A missing component in your theory of change?
Theory of change mechanisms are where you describe how you want people to engage with your activities; the kind of relationship you establish; and the thought processes you want them to go through in order to achieve the outcomes and impact you want.