Zeitschrift für Evaluation: Issue 1/2025, 24. Volume What Works is not the Plan, but its Execution

Implementation fidelity is the degree of overlap between the actual execution of a program and the program’s initial plan. Implementation research shows that due to a number of reasons programs can deviate from their initial plan more often than not. Accordingly, evaluations have to consider implementation fidelity adequately. In formative evaluation, deviations from a program’s concept can suggest possible improvements, while in summative evaluations, neglecting implementation fidelity can lead to erroneous attributions of effectiveness. While a number of approaches for operationalizing implementation fidelity have been proposed in the literature, a domain independent, as far as possible generic, and theoretically derived system of criteria for measuring implementation fidelity is still missing. The article reviews the state of the literature and proposes a comprehensive system of criteria for determining implementation fidelity in evaluation studies which is theoretically based on the well-established logic model approach.

Keywords
implementation, implementation fidelity, criteria, logic model, program evaluation