title: An evaluation of the diagnostic accuracy of Pathfinder.
abstract: We present an evaluation of the diagnostic accuracy of Pathfinder, an expert system that assists pathologists with the diagnosis of lymph node diseases. We evaluate two versions of the system using both informal and decision-theoretic metrics of performance. In one version of Pathfinder, we assume incorrectly that all observations are conditionally independent. In the other version, we use a belief network to represent accurately the probabilistic dependencies among the observations. In both versions, we make the assumption--reasonable for this domain--that diseases are mutually exclusive and exhaustive. The results of the study show that (1) it is cost effective to represent probabilistic dependencies among observations in the lymph node domain, and (2) the diagnostic accuracy of the more complex version of Pathfinder is at least as good as that of the Pathfinder expert. In addition, the study illustrates how informal and decision-theoretic metrics for performance complement one another.
authors.affiliation: University of Southern California, Los Angeles 90033.
authors.forename: D E
authors.initials: DE
authors.lastname: Heckerman
authors.forename: B N
authors.initials: BN
authors.lastname: Nathwani
mesh_terms: D003936:Diagnosis, Computer-Assisted; D005069:Evaluation Studies as Topic; D005103:Expert Systems; D006801:Humans; D008206:Lymphatic Diseases / Q000175:diagnosis*; D011336:Probability