Establishing a Theory of Change model

The first step when designing your evaluation should be to map the components of your intervention and describe how you will achieve the desired outcomes. This is known as a Theory of Change – your theory for predicting how the intervention will bring about the desired change.

What is a Theory of Change?

For the purposes of this framework,  a Theory of change is defined as:

“a visual representation of a programme’s inputs, activities, outputs, outcomes and underlying causal mechanisms.”

A Theory of Change describes the underlying assumptions about how planned activities will lead to intended outcomes. By developing a model setting out your Theory of Change, you can understand how different aspects of your programme fit together to achieve your final goal.

In the event of a null or negative result, a well-designed Theory of Change will help the evaluator distinguish between:

  • theory fallacy – the underlying assumptions are not leading to the intended outcomes;
  • implementation fallacy – the intervention was not implemented as intended; or
  • methodology fallacy – unsuitable evaluation methods were used or suitable methods were used insufficiently.

A Theory of Change model allows you to:

  • describe the need you are trying to address
  • the changes you want to make (your outcomes); and
  • how you plan to achieve these changes (your activities)

This is best done collectively, drawing on the experience of those who will work on the service or scheme’s implementation. 

Why do I need a Theory of Change?

A Theory of Change helps you answer the following questions:

1. Is this the right intervention?
A Theory of Change requires you to model your desired outcomes, before deciding on the intervention. This allows you to design interventions which can achieve the desired outcomes. It also allows you to critically assess the intervention you have designed and be transparent about how it will lead to the long-term goal.

2. Is your intervention achievable?
A Theory of Change sets out how the intervention is intended to work and the resources necessary to deliver the intervention. This allows you to identify whether you need to review your outcomes and adapt the activities to achieve them, given the resources available.

3. Is your intervention testable?
A Theory of Change model will help identify questions for the evaluation and sources of evidence. Once you have identified sources of evidence, you will be able to assess if things are progressing (or not) and if you are on course to meet your short and medium-term outcomes.

How do I develop a Theory of Change?

Developing an impact-focussed Theory of Change is straightforward when you approach it using the following steps in sequence, rather than mapping from activity to impact.

Doing so will structure your thinking, starting broadly with the current state of play (steps 1&2) and identifying the outcomes (step 3) which will enable you to get where you want to be (step 4), followed by the specific things that need to happen to get you there (steps 5-7). Then you can consider the assumptions (step 8) underpinning your Theory of Change – this will help you to understand whether you can achieve your intended impact within the context you are operating.

Theories of Change are best developed as part of a group discussion, preferably with an external facilitator. Your team should go through the following sections.

  1. Situation: What is the context in which you are working? What problem is your intervention trying to address or resolve?
  2. Aims: What goal or objective is the intervention aiming to achieve? What is your proposed solution to the problem? Your aim should be linked to your overarching strategy.
  3. Outcomes: Which short and intermediate-term outcomes need to be in place for the long-term goals of your intervention (or impacts) to be achieved?
  4. Impact: What is the long-term goal which relates to your situation and aims? What will result from the removal of the problem?
  5. Activities: Outline the interventions you believe (supported by your rationale and assumptions) will bring about your desired change. Activities mobilise your inputs to produce outputs.
  6. Outputs: What are the direct results or deliverables of your intervention which enable you to achieve your outcomes?
  7. Inputs: What are the human, financial and organisational resources required to deliver your activities and, in turn, achieve your desired outcomes?
  8. Rationale & assumptions: What are your assumptions? Your assumptions are the conditions which underpin, and are necessary for, the success of the intervention. What is your rationale? Your rationale explains why one outcome is needed to achieve another. Including your assumptions and rationale (which are often supported by research) strengthens the plausibility of your theory and the likelihood that its stated goals can be achieved.

Once you have developed the Theory of Change, it’s important to write it up in a formal document and save it where everyone can see it and refer back to it. It may also be helpful to share with key stakeholders.

Consider the life-stage of your initiative

It’s important to consider how much we already know about how the initiative under evaluation operates. Looking at the Theory of Change, consider how many of the assumptions you are confident of, and how much we already know about whether inputs lead to activities, leading to outputs.

This influences the relative emphasis we would place on measuring impact versus understanding process.

  • For instance, if it’s a brand-new initiative, we might classify it as a pilot because we don’t yet know whether it is technically possible to run, whether people will engage with it, and so on. In this case, we might shift the focus of the evaluation more towards understanding the process of delivering the initiative, with less of an emphasis on robust measurement of the causal impact of the initiative.
  • Likewise, if the programme is very complex, and contains multiple elements, we might want relatively more process evaluation to understand how the different elements fit together.
  • An established, relatively straightforward service with a high volume of interactions might need relatively more focus on the effectiveness of the service, thus measuring the impact.

Over time, the goal is to be confident that each stage in the Theory of Change flows on to the next; however, this is a process that will occur over multiple years and multiple phases of evaluation.

Further guidance

The following video is a recording of a webinar TASO held on 3 June 2020 on the first step in its evaluation guidance – Step 1: Diagnose.

The session outlines:

What is a theory of change?
Why do I need a theory of change?
How do I develop a theory of change?