Between 1980 and 2000, a complicated war raged in Peru, pitting the country’s government against at least two political guerilla organizations, and forcing average people to band together into armed self-defense committees. The aftermath was a mess of death and confusion, where nobody knew exactly how many people had been murdered, how many had simply vanished, or who was to blame.
“The numbers had floated around between 20,000 and 30,000 people killed and disappeared,” says Daniel Manrique-Vallier. “But nobody knew what the composition was. Non-governmental organizations were estimating that 90% of the deaths were the responsibility of state agents.”
Manrique-Vallier, a post-doc in the Duke University department of statistical science, was part of a team that researched the deaths for Peru’s Truth and Reconciliation Commission. Their results were completely different from those early estimates. Published in 2003, the final report presented evidence for nearly 70,000 deaths, 30% of which could be attributed to the Peruvian government.
How do you find 40,000 extra dead bodies? How do you even start to determine which groups killed which people at a time when everybody with a gun seemed to be shooting civilians? The answers lie in statistics, data analysis, and an ongoing effort to use math to cut through the fog of war. Read the rest