Self-assessment of medical knowledge: do physicians overestimate or underestimate?

The relationship between doctors' medical knowledge and their inability to assess correctly what they know was investigated. Sixty out of 65 hospital physicians sat a MRCP Part 1 multiple-choice examination. In addition to the factual questions, they had to estimate how certain they were that their answers were correct. We confirmed that factual knowledge increased with clinical experience from the grade of house officer through to that of senior registrar. The self-assessment of likelihood of being correct revealed that, on average, doctors underestimated their knowledge by 8%. However, those who had passed their MRCP examination within the past three years over-estimated on average by 6%. We suggest that this inadequacy of self-assessment could have serious clinical implications, and should be assessed.