Table 1 The key aims of realist evaluation

Aim 1: Understanding the theory of programmes and how they work

1. Interventions are theories and will therefore have theories of change

2. These theories are embedded in social systems

3. They are active and effects are produced by, and require, the active engagement of actors

4. They are also parts of open systems; there may be unanticipated events, political change, inter-programme and intra-programme interactions that influence how interventions bring about change

Aim 2: To understand and explain how, why, and for whom programmes work when implemented

5. Identify intervention mechanisms; emphasis on how an intervention works

6. The importance of context; conditions in which the intervention is introduced and which are relevant to its functioning

7. Outcome patterns; intended and unintended consequences

8. Context-mechanism-outcome pattern configurations (CMOs) explaining the theory of how programmes activate mechanisms, amongst whom, and in what conditions.

It is the synergy of CMO pattern configurations that is of interest, as opposed to merely separately identifying and describing ‘mechanisms’, ‘contexts’, and ‘outcomes’

Adapted from Pawson and Tilley [26]