Theory-based evaluations: Framing the existence of a new theory in evaluation and the rise of the 5th generation

In this article we defend the idea that theory-based evaluationscontribution analysis, logic analysis, and realist evaluationare complementary components of a new theory in evaluation. We also posit that we are currently observing the emergence of a fifth generation in evaluation: the explanation generation. Theory-based evaluations have featured prominently in the discourse of evaluators since the mid-1980s. They have developed mainly in response to the need for evaluation of complex interventions. In this article we analyze certain approaches that have matured in their design and application. We use the framework of Shadish et al. to analyze the ontological, epistemological, and methodological foundations of various theory-based approaches in evaluation to appraise their similarities and differences. We observe that all these approaches are grounded in critical realism. Similarities seen in their ontological, epistemological, and methodological positionings, as well as their complementarity in terms of the evaluative questions they address, suggest we may be observing the consolidation of a new theory in evaluation and the emergence of a fifth generation.