It’s all theory-based and counterfactual

Two of my favourite articles on #evaluation are Cook’s (2000) argument that all impact evaluations, RCTs included, are theory-based and Reichardt’s (2022) argument that there’s always a counterfactual, if not explicitly articulated then not far beneath the surface. I think both arguments are irrefutable, but how we can build on theirs and others’ work to improve evaluation commissioning and delivery seems a formidable challenge given the fiercely defended dichotomies in the field.

If all impact evaluation really is theory-based then it’s clear there’s huge variation in the quality of theories and theorising. If all impact evaluation depends on counterfactuals then there is huge variation in how compelling the evidence is for the counterfactual outcomes, particularly when there is no obvious comparison group.

Clarifying these kinds of distinctions is, I think, important for improving evaluations and the public services and other programmes they evaluate.


Cook, T. D. (2000). The false choice between theory-based evaluation and experimentation. In A. Petrosino, P. J. Rogers, T. A. Huebner, & T. A. Hacsi (Eds.), New directions in evaluation: Program Theory in Evaluation: Challenges and Opportunities (pp. 27–34). Jossey-Bass.

Reichardt, C. S. (2022). The Counterfactual Definition of a Program Effect. American Journal of Evaluation, 43(2), 158–174.