The curious case of the realist trial: Methodological oxymoron or unicorn?

Realist evaluation and experimental designs are both well-established approaches to evaluation. Over the past 10 years, realist trials-evaluations purposefully combining realist evaluation and experimental designs-have emerged. Informed by a comprehensive review of published realist trials, this article examines to what extent and how realist trials align with quality standards for realist evaluations and randomized controlled trials and to what extent and how the realist and trial aspects of realist trials are integrated. We identified only few examples that met high-quality standards for both experimental and realist studies and that merged the two designs.