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Developing a good theory of change

This short video introduces our 10 steps to evaluation success, and answers a set of questions about a theory of change: what is it, why does it matter, and how to use scientific findings to test the assumptions about how an intervention is designed to work.


Developing a good theory of change

Early intervention is about improving outcomes for children and families. Effective early intervention works to prevent problems from occurring in the first place, or tackle them head-on before they get worse.

Evaluation is essential for ensuring that your intervention is effective at preventing poor outcomes, supporting children’s development, and providing the benefits that it has been designed to provide.

Understanding and measuring the impact of your intervention is a journey. There are a number of steps to making sure your intervention is as effective as it can be.

Our 10 steps for evaluation success map out this journey, from the development of a theory of change, to logic models, feasibility studies, pilot evaluations, impact assessments, and quality assurance for interventions offered on a wide scale.

The first and most important step towards demonstrating your intervention’s impact is the development of a high-quality theory of change.

What is a theory of change?

A theory of change encapsulates some crucial details about why your intervention is necessary and what it aims to achieve it.

A theory of change can come in many different visual or written forms. But whatever it looks like, it should answer some fundamental questions about your intervention.

  • Why is the intervention needed for children’s development?
  • Who is the intervention for? What are the crucial characteristics of the people who will be taking part?
  • How does the intervention work? What is its content, and what will participants do?
  • What is the primary outcome for the children taking part, and why is this outcome important to their development?

Together, these features of an intervention start to paint a picture of how an intervention works.

It’s also the essential first step in being ready to evaluate the intervention in the future.

Why does a theory of change matter?

Articulating a theory of change is vital for several reasons.

  • It enables you to communicate the rationale for an intervention, both within your organisation and more widely
  • To recognise and start to address any uncertainties or risks in your plans for the intervention
  • To ensure everyone involved is on the same page, which can help to improve how your intervention is delivered
  • And to lay the foundation for future evaluation, which will test whether your intervention has achieved what was intended.

Learning the lessons from this evaluation will help you to refine and adapt your theory of change, and improve the effectiveness of your intervention in the long run.

Testing your assumptions

It may seem obvious why a particular intervention is needed, or how it will work to improve children’s lives.

But often, there are a set of assumptions involved, which may not have been tested, and may not even be true.

Let’s imagine an intervention that aims to reduce aggressive behaviour in children under the age of 10. This intervention works by spotting children showing signs of aggression, and giving them extra playtime.

The idea is that this will give them more time to learn better social skills, which will improve their behaviour now and reduce the risk of serious behavioural problems later.

Now, there are several assumptions involved here that we would need to investigate, if we were trying to produce a high-quality theory of change for this intervention.

  • Does playtime improve social skills?
  • Is a lack of social skills associated with increased aggression?
  • Does improving social skills improve behaviour for children who are being aggressive?
  • And does this work in the long run?

It is essential to answer these questions – to challenge your assumptions – if you’re going to produce a good theory of change and set yourself up to evaluate the intervention in the future.

Creating a science-based theory of change

The best way to remove the untested assumptions from your theory of change is to use the existing evidence from scientific research.

You can use what is known from research into child development to pin down who the intervention is for, to clarify what the content will be, and to identify its primary outcomes for the people taking part.

Intervention developers frequently rely on their own experiences to answer these questions. These experiences can play an important part in creating a theory of change. However, using science will allow you to reflect on any hidden assumptions about how your intervention operates.

Using findings from research helps you to iron out the uncertainties and untested assumptions in your theory of change.

As a result, interventions that are rooted in findings from research have a greater chance of having a positive impact on the lives of children and families.

Let’s think again about trying to reduce aggressive behaviour in young children, and look at a science-based theory of change, based on what the academic literature says about child development.

All children are aggressive during the preschool years. In fact, human beings are at their most aggressive between the ages of 2 and 3.

Coercion theory is based on the observation that many parents inadvertently reinforce aggressive behaviour when they argue with their child or give in to their child’s demands. In other words, aggressive child behaviour coerces ineffectual parent responses, which in turn coerce more aggressive child behaviours. This suggests that one way to tackle aggressive child behaviour is to break this cycle.

This intervention would work with parents and caregivers of preschool age children. Parents and caregivers would be taught strategies for responding more effectively to their children’s aggressive behaviour.

In the short term, parents should learn and be able to use these new strategies. In the medium term, their children’s behaviour should improve. In the long term, improved behaviour should support children to avoid crime and other forms of antisocial behaviour.

This theory of change explains why the intervention is needed, how it would work and what it would achieve, working from a set of science-based assumptions. By referring to the academic literature, you can incorporate into your theory of change what we know about children’s development and how interventions can influence outcomes.

Developing a good, science-based theory of change helps everyone involved in your intervention to understand and explain why it’s needed and how it will work.

It’s also the vital first step on the evaluation journey, so that you can demonstrate the positive impact your intervention is having on the lives of children and families.

About the contributors

Hannah Wilson

Hannah is a policy & practice adviser at EIF.

Dr Kirsten Asmussen

Kirsten is head of what works, child development, at EIF.

Tom McBride

Tom is director of evidence at EIF.