Guessing right - whether and how medical students give incorrect reasons for their correct diagnoses.

Clinical reasoning is one of the central competencies in everyday clinical practice. Diagnostic competence is often measured based on diagnostic accuracy. It is implicitly assumed that a correct diagnosis is based on a proper diagnostic process, although this has never been empirically tested. The frequency and nature of errors in students' diagnostic processes in correctly solved cases was analyzed in this study. 148 medical students processed 15 virtual patient cases in internal medicine. After each case, they were asked to state their final diagnosis and justify it. These explanations were qualitatively analyzed and assigned to one of the following three categories: correct explanation, incorrect explanation and diagnosis guessed right. The correct diagnosis was made 1,135 times out of 2,080 diagnostic processes. The analysis of the associated diagnostic explanations showed that 92% (1,042) reasoning processes were correct, 7% (80) were incorrect, and 1% (13) of the diagnoses were guessed right. Causes of incorrect diagnostic processes were primarily a lack of pathophysiological knowledge (50%) and a lack of diagnostic skills (30%). Generally, if the diagnosis is correct, the diagnostic process is also correct. The rate of guessed diagnoses is quite low at 1%. Nevertheless, about every 14th correct diagnosis is based on a false diagnostic explanation and thus, a wrong diagnostic process. To assess the diagnostic competence, both the diagnosis result and the diagnostic process should be recorded.