Estimating the Number of Fatal Victims of the Peruvian Internal Armed Conflict, 1980-2000: an application of modern multi-list Capture-Recapture techniques

TL;DR

This paper applies advanced multi-list Capture-Recapture techniques with Bayesian methods to estimate the total number of victims in Peru's internal conflict, providing new insights and methodological improvements.

Contribution

It introduces a novel framework for handling incomplete stratification data in Capture-Recapture models using MCMC, and applies it to a large, complex dataset from Peru's conflict.

Findings

Estimated total victims between 58,234 and 65,958.

Found that Shining Path guerrillas killed more people than the armed forces.

Provided methodological lessons for conflict casualty estimation.

Abstract

We estimate the number of fatal victims of the Peruvian internal armed conflict between 1980-2000 using stratified seven-list Capture-Recapture methods based on Dirichlet process mixtures, which we extend to accommodate incomplete stratification information. We use matched data from six sources, originally analyzed by the Peruvian Truth and Reconciliation Commission in 2003, together with a new large dataset, originally published in 2006 by the Peruvian government. We deal with missing stratification labels by developing a general framework and estimation methods based on MCMC sampling for jointly fitting generic Bayesian Capture-Recapture models and the missing labels. Through a detailed exploration driven by domain-knowledge, modeling and refining, with special precautions to avoid cherry-picking of results, we arrive to a conservative posterior estimate of 58,234 (CI95% = [56,741, 61,289]), and a more liberal estimate of 65,958 (CI95% = [61,462, 75,387]) fatal victims. We also determine that the Shining Path guerrillas killed more people than the Peruvian armed forces. We additionally explore and discuss estimates based on log-linear modeling and multiple-imputation. We finish by discussing several lessons learned about the use of Capture-Recapture methods for estimating casualties in conflicts.