Expert testimony based on decision analysis: a malpractice case report. OBJECTIVE: Expert testimony in malpractice cases is often subjective and biased. Decision-analytic techniques might provide an objective basis for such testimony. DESIGN: Case report. This article reports the case of a patient with chest pain that resulted in a malpractice suit alleging a delay in diagnosis of coronary artery disease. SETTING: The case occurred in a private practice; the expert witnesses and the decision analysis originated from a university teaching hospital. METHODS: A decision tree and threshold analysis were used to define the thresholds of disease probability at which either testing or treatment should be implemented. The expert testimony of two witnesses that exercise stress testing was the standard of care was compared with the results of the decision analysis. MAIN RESULTS: Decision analysis supported the view that cardiac catheterization would have been the more appropriate test. CONCLUSIONS: Techniques of decision analysis provide a structured and quantitative basis for empirical judgment and may help to minimize current problems with expert testimony. 