Telling Context from Mechanism in Realist Evaluation: The role for theory

Realist evaluation is based on the premise that aspects of context trigger particular mechanisms in response to an intervention, which result in observable outcomes. This is often expressed in the formula C+M=O. Contexts are defined as the conditions that an intervention operates in (often but not exclusively sociocultural), while mechanisms are understood to be the future action that people take in response to the intervention. There is much debate, however, about the definitions and because distinctions are not clear-cut it can be difficult to decide which is which, particularly when the intervention concerns some program of curricular intervention. In this paper we discuss how we resolved this dilemma in an evaluation of a curriculum change in 13 universities in Australia and New Zealand. In that case we found a cascade of contexts and mechanisms, whereby what was a mechanism from one point of view (such as the decisions involved in course design) became a context triggering later mechanisms (such as teacher and student behaviours). The scholarly literature defining curriculum helped us to organise our thinking and subsequent analysis in a rational way, but in many evaluations there may not be a handy body of work that discusses how to understand the topic of the intervention in this way, nor do many consultant evaluators have the luxury of long hours in the library. We consider some ways in which evaluators might decide on defining contexts and mechanisms in principled ways and some of the consequences of those decisions.