As part of a multidisciplinary study of malpractice and medical injury, the Harvard Medical Practice Study set forth to estimate the incidence of injuries caused by medical management and those resulting from negligent or substandard care. A review of more than 30,000 randomly selected acute care hospitalized cases was used to obtain estimates of injuries. The authors found that adverse events occurred in 3.7% of hospitalizations; 27% of these were due to negligence. Population estimates yielded more than 2 million adverse events in New York hospitals in 1984, with more than 20,000 of these adverse events involving negligence.