An August 2003 National Bureau of Economic Research paper by Katherine Baicker and Amitabh Chandra found that (1) "increases in malpractice payments made on behalf of physicians do not seem to be the driving force behind increases in premiums"; (2) "increases in malpractice costs (both premiums overall and the subcomponent factors) do not seem to affect the overall size of the physician workforce, although they may deter marginal entry, increase marginal exit, and reduce the rural physician workforce"; and (3) "there is little evidence of increased use of many treatments in response to malpractice liability at the state level, although there may be some increase in screening procedures such as mammography."