Bayes' theorem and the physical examination: probability assessment and diagnostic decision making

To determine how examination findings influence the probability assessment and diagnostic decision making of third- and fourth-year medical students, internal medicine residents, and academic general internists. In a 2008 cross-sectional, Web-based survey, participants from three medical schools were asked questions about their training and eight examination scenarios representing four conditions. Participants were given literature-derived preexamination probabilities for each condition and were asked to (1) estimate postexamination probabilities (post-EPs) and (2) select a diagnostic choice (report that condition is present, order more tests, or report that condition is absent). Participants' inverse transformed logit (ITL) mean post-EPs were compared with corresponding literature-derived post-EPs. Of 906 individuals invited to participate, 684 (75%) submitted a completed survey. In two of four scenarios with positive findings, the participants' ITL mean post-EPs were significantly less than corresponding literature-derived post-EP point estimates (P