A total of 1,166 people were killed by police in the U.S. in 2015
Law enforcement-related deaths were vastly undercounted in a key national database in 2015 because they were misreported on death certificates
Rates of undercounting were highest in lower-income counties, among blacks and people under age 18, and when deaths involved non-firearm means such as Taser
Official death certificates in the U.S. failed to count more than half of the people killed by police in 2015 — and the problem of undercounting is especially pronounced in lower-income counties and for deaths that are due to Tasers, according to a new study from Harvard T.H. Chan School of Public Health.