Measuring homicides across the world helps us understand violent crime and how people are affected by interpersonal violence.

But measuring homicides is challenging. Even homicide researchers do not always agree on whether the specific cause of death should be considered a homicide. Even when they agree on what counts as a homicide, it is difficult to count all of them.

In many countries, national civil registries do not certify most deaths or their cause. Besides lacking funds and personnel, a body has to be found to determine whether a death has happened. Authorities may also struggle to distinguish a homicide from a similar cause of death, such as an accident.

Law enforcement and criminal justice agencies collect more data on whether a death was unlawful — but their definition of unlawfulness may differ across countries and time.

Estimating homicides where neither of these sources is available or good enough is difficult. Estimates rely on inferences from similar countries and contextual factors that are based on strong assumptions. So how do researchers address these challenges and measure homicides?

In our work on homicides, we provide data from five main sources:

The WHO Mortality Database (WHO-MD)1 The Global Study on Homicide by the UN Office on Drugs and Crime (UNODC)2 The History of Homicide Database by Manuel Eisner (20033 and 20144) The Global Burden of Disease (GBD) study by the Institute for Health Metrics and Evaluation (IHME)5 The WHO Global Health Estimates (WHO-GHE)6 These sources all report homicides, cover many countries and years, and are frequently used by researchers and policymakers. They are not entirely separate, as they partially build upon each other.