Differences in time anesthesiologists spent supervising by exemption status and region. The figure presents the percent of anesthesiologist time spent supervising nonphysician providers by region and whether the anesthesiologist’s state has been exempted from the Medicare supervision requirement. The Ns stand for the total number of states represented in the data for a given census region. Differences are statistically significant when controlling for age, years of experience, census region, urban/rural location, race/ethnicity, birth country, whether educated in United States, marital status, and children.