A new study by researchers at Brigham and Women’s Hospital, an affiliate of Harvard Medical School, found that the rate of paid medical malpractice claims in the U.S. has declined by 55.7% over the past two decades (1992-2014) while average payouts have increased about 23%, based on data in the National Practitioner Data Bank.

The study also found that the most common type of allegation was an error in diagnosis (31.8% of all paid claims), followed by errors related to surgery (26.9%) and errors related to medication or treatment (24.5%).

The hospital’s press release calls the study the first to examine paid medical malpractice claims by physician specialty on a national level. The results were published on March 27 in the American Medical Association’s publication, JAMA Internal Medicine.