This article develops a framework for the causal analysis of critical events in case study research. A critical event is defined as a contingent event that is causally important for an outcome in a specific case. Using set-theoretic analysis, this article offers definitions and measurement tools for the study of contingency and causal importance…

Evaluators are often called upon to assess the effects of programs. To assess a program effect, evaluators need a clear understanding of how a program effect is defined. Arguably, the most widely used definition of a program effect is the counterfactual one. According to the counterfactual definition, a program effect is the difference between…

In this article, the author presents his views on Michael's (1975) and Baron and Galizio's (2005) arguments on eliminating the distinction between positive and negative reinforcement. He first discusses Michael's concept of these two types of operations and contrasts it with the notions of Baron and Galizio. The author provides the readers his own…