Objective: To examine whether physicians attend to gender prevalence data in diagnostic decision making for coronary heart disease (CHD) and to test the hypothesis that previously reported gender differences in CHD diagnostic certainty are due to discrimination arising from reliance on prevalence data ("statistical discrimination").

Data sources: A vignette-based experiment of 256 randomly sampled primary care physicians conducted from 2006 to 2007.

Study design: Factorial experiment. Physicians observed patient presentations of cardinal CHD symptoms, standardized across design factors (gender, race, age, socioeconomic status).

Data collection: Structured interview.

Principal findings: Most physicians perceived the U.S. population CHD prevalence as higher in men (48.4 percent) or similar by gender (44.9 percent). For the observed patient, 52 percent did not change their CHD diagnostic certainty based on patient gender. Forty-eight percent of physicians were inconsistent in their population-level and individual-level CHD assessments. Physicians' assessments of CHD prevalence did not attenuate the observed gender effect in diagnostic certainty for the individual patient.

Conclusions: Given an adequate presentation of CHD symptoms, physicians may deviate from their prevalence data during diagnostic decision making. Physicians' priors on CHD prevalence did not explain the gender effect in CHD certainty. Future research should examine personal stereotypes as an explanation for gender differences.