Official counts of homicides by police seriously undercount incidents, according to a study from Harvard T.H. Chan School of Public Health, but a relatively new national data system, currently in use in 32 states, could be a crucial tool for gathering more comprehensive information, say the researchers. The study, published online March 17 in the American Journal of Public Health, found that the U.S. Centers for Disease Control and Prevention’s National Violent Death Reporting System (NVDRS) provided more complete and accurate data on police homicides compared with two other national data systems.
“The U.S. is trying to get a handle on police homicides, but how do we learn which policies best prevent these deaths and protect police if we can’t even get an accurate count of them?” said Ms. Catherine Barber of the Harvard Injury Control Research Center (HICRC) at Harvard Chan School. “The NVDRS could be the best solution to this vexing problem.”
Counts of homicides by police are currently tracked by two official national data sources: the CDC’s National Vital Statistics System and Supplementary Homicide Reports (SHRs) from the FBI’s Uniform Crime Reports System. But these data sources each rely on a single source — death certificates for the CDC’s system and voluntary police reporting for the FBI’s system — and the study suggests that each undercounts police homicides by as much as half. In addition, the extent of undercounting varies greatly by state, making comparisons among states and municipalities unreliable.
Given the limitations of these data sources, the researchers looked at whether the NVDRS could be a better alternative. A relatively new data system created in 2003, the NVDRS pools information on all violent deaths from participating states. It includes detailed coded data from multiple sources—from death certificates, police reports, coroner or medical examiner records, and crime labs. It also includes short abstracts that describe the circumstances of each incident.
Although 32 states currently use the NVDRS, its use hasn’t expanded further because of limited federal funding — which states must apply for in order to implement the system.
“Expanding the NVDRS to a 50-state system — as President Obama’s budget calls for — and implementing a couple of technical fixes that we identify will supply the nation not only with a more accurate count of these deaths but detailed data on the people, places, weapons, and circumstances involved,” said senior author of the study, Dr. David Hemenway, professor of health policy at Harvard Chan School.