Theory Driven Evaluations

Chen's book, and his subsequent work, introduced the role of program theory and program logic diagrams as core elements essential to evaluaton method. This approach supports the blending of "hard science" schools of evaluation that stress scientific method, random samples, experimential and quasi-experimental design with the naturalistic, social relations oriented schools by emphasizing the importance of bringing to an evaluation extensive subject-matter knowledge for the development of program theory. Program theory (and associated logic diagrams) then takes precedence in framing the research questions and indicating how methods should be deployed, as well as how quantitative and qualitative methods should be configured in an evaluation. This is different from the simple joining of impact and process evaluation on a project because it moves some elements of process evaluation to the heart of strategy for impact evaluation, and improves both quantitative and qualitative results for both internal validity and generalization. Chen proposes an extensive typology for these relationships. In some ways the book documents a conceptual breakthough for evaluation that also occurs in every social science that has experienced a "struggle of methods" between schools of quantitative and qualitative insights. There are "many roads to the city," and Campbell's quasi-experimental design school, for example, includes these synergies in practical work. But this is the book that made the difference in this field (evaluation). It is quite well written, clear, and can serve as a core text on evaluation method.