Authors Reply:—We appreciate Dr. Keller's interest in our paper and his thoughtful suggestion that our finding of a July spike in medication errors might result from “poor teamwork and coordination between the residents and the hospital staff, including the attending physicians, nurses, and pharmacists.” In our article, we indeed noted that the July spike “seems to result at least partly from changes associated with new medical residents.” Dr. Keller is suggesting a plausible example of such a change.

In our article, we also noted that the death certificates we analyzed are unsuitable for explicating the detailed mechanisms producing the July spike. We hope that our article and Dr. Keller's letter will stimulate new research with different datasets that are capable of identifying the detailed processes that cause the July spike in medication errors.