Timing bias in the psychiatry subject examination of the National Board of Medical Examiners.

Objective: The authors investigate whether the timing of the psychiatry clerkship influences scores on the National Board of Medical Examiners (NBME) subject exam as has been reported for other clerkships. The authors attempt to identify which clerkships, if any, offer an advantage when taken before psychiatry.

Methods: Mean aggregate exam scores over 4 years were calculated according to clerkship sequence. An analysis of variance was conducted to assess the effect of sequence on test scores. Pairwise comparisons (t tests) were performed to determine whether students who completed one particular clerkship before psychiatry scored higher on the subject examination than students who completed the clerkship after psychiatry.

Results: Students who take psychiatry near the end of the clerkship sequence score higher than students who take psychiatry as a first clerkship. The differences are small but significant. The mean score for students taking psychiatry first was 72.81, compared to a score of 78.51 for students taking the clerkship last. No single clerkship is more likely than another to increase test scores when taken before psychiatry.

Conclusions: Clerkship directors must be aware of the timing bias in subject exam scores. However, the bias may not be sufficient to justify abandoning use of the subject examinations.