Probabilistic Prediction: Some Experimental Results

This article concerns a study in which personal probability assessments regarding the outcomes of football games were obtained. The results reported here, which include a detailed investigation of the assessments, an evaluation of the assessments in an inferential context and in a decision-theoretic context, and a discussion of the performance of a consensus, show that methods such as scoring rules and bets are useful in leading individuals to make careful probability assessments. Considerable variability existed among subjects, however, with predictions determined by mechanical schemes and by the organized betting market proving superior to those of many of the subjects.