In a voluntary examination such as the ITE-IM, selection bias may influence test scores over time. It is possible that "better" programs offered the examination to their interns when the test first became available and that the recent decrease in scores among first-year housestaff who have graduated from medical schools in the United States reflects the fact that the examination is now being administered by a wider array of programs. It should be noted, however, that the decrease in scores is less evident among interns who have graduated from international medical schools. On the 1994 ITE-IM, the downward trend in scores for first-year U.S. medical graduates continued (average score, 55.6); this score was lower than that for first-year international graduates (average score, 55.8) for the first time. In addition, most programs that offer the examination to interns also offer it to third-year housestaff. The decrease in scores over time is less prominent in the third-year comparison group, suggesting that selection bias may not be a major explanation of our observations.

It is not surprising that a high correlation exists between scores for examinations that use a similar format, have a high reliability, and test core knowledge in internal medicine [1]. We have not correlated scores of trainees who took both the ITE-IM and ABIM examination; however, others have done so [2, 3] and have seen the same high association as that noted in two of the previous letters. In addition, we think that the ITE-IM provides better insight into the working knowledge of the resident because most residents do not spend much time preparing for this examination. For this reason, it may be particularly useful in identifying subject areas that need additional emphasis. However, the subtest (or organ-specific) scores for the ITE-IM are not as reliable or accurate as the total test score for subject areas in which relatively few questions are asked. Therefore, subtest results of the ITE-IM should not be used alone to develop curricula for remedial work for an individual resident.