Thursday, August 14, 2008

Would you trust your doctors' prognosis?

Our study of doctors' prognoses showed that most doctors over-estimate their patients' chances of survival. This opens up the question of how we could improve the accuracy of prognosis and limit some of the costs patients' families and health care systems suffer when doctors make wrong prognoses. See: Alexander, M. and Christakis, N.A. "Bias and Asymmetric Loss in Expert Forecasts: A Study of Physician Prognostic Behavior with Respect to Patient Survival," Journal of Health Economics 27 (2008): 4: 1095-1108. Here is the abstract:

We study the behavioral processes undergirding physician forecasts, evaluating accuracy and systematic biases in estimates of patient survival and characterizing physicians’ loss functions when it comes to prediction. Similar to other forecasting experts, physicians face different costs depending on whether their best forecasts prove to be an overestimate or an underestimate of the true probabilities of an event. We provide the first empirical characterization of physicians’ loss functions. We find that even the physicians’ subjective belief distributions over outcomes are not well calibrated, with the loss characterized by asymmetry in favor of over-predicting patients’ survival. We show that the physicians’ bias is further increased by (1) reduction of the belief distributions to point forecasts, (2) communication of the forecast to the patient, and (3) physicians’ own past experience and reputation.

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