Validity and generalization in future case study evaluations

Validity and generalization continue to be challenging aspects in designing and conducting case study evaluations, especially when the number of cases being studied is highly limited (even limited to a single case). To address the challenge, this article highlights current knowledge regarding the use of: (1) rival explanations, triangulation, and logic models in strengthening validity, and (2) analytic generalization and the role of theory in seeking to generalize from case studies. To ground the discussion, the article cites specific practices and examples from the existing literature as well as from the six preceding articles assembled in this special issue. Throughout, the article emphasizes that current knowledge may still be regarded as being at its early stage of development, still leaving room for more learning. The article concludes by pointing to three topics worthy of future methodological inquiry, including: (1) examining the connection between the way that initial evaluation questions are posed and the selection of the appropriate evaluation method in an ensuing evaluation, (2) the importance of operationally defining the ‘complexity’ of an intervention, and (3) raising awareness about case study evaluation methods more generally.