From Meehl to fast and frugal heuristics (and back) - New insights into how to bridge the clinical-actuarial divide

It is difficult to overestimate Paul Meehl's influence on judgment and decision-making research. His 'disturbing little book' (Meehl, 1986, p. 370) Clinical versus Statistical Prediction: A Theoretical Analysis and a Review of the Evidence (1954) is known as an attack on human judgment and a call for replacing clinicians with actuarial methods. More than 40 years later, fast and frugal heuristics - proposed as models of human judgment - were formalized, tested, and found to be surprisingly accurate, often more so than the actuarial models that Meehl advocated. We ask three questions: Do the findings of the two programs contradict each other? More generally, how are the programs conceptually connected? Is there anything they can learn from each other? After demonstrating that there need not be a contradiction, we show that both programs converge in their concern to develop (a) domain-specific models of judgment and (b) nonlinear process models that arise from the bounded nature of judgment. We then elaborate the differences between the programs and discuss how these differences can be viewed as mutually instructive: First, we show that the fast and frugal heuristic models can help bridge the clinical - actuarial divide, that is, they can be developed into actuarial methods that are both accurate and easy to implement by the unaided clinical judge. We then argue that Meehl's insistence on improving judgment makes clear the importance of examining the degree to which heuristics are used in the clinical domain and how acceptable they would be as actuarial tools.