Guatemala 2011 – Developing Sampling Methods to Help Convict Perpetrators

During 36 years of internal armed conflict, which ended in 1996, an estimated 200,000 Guatemalans were killed or disappeared. HRDAG researchers returned to Guatemala in 2006 to analyze a sample of the estimated 46 million records discovered in the archive of the now disbanded Guatemalan National Police. HRDAG statisticians Daniel Guzmán, Romesh Silva, Patrick Ball and Tamy Guberek, together with Paul Zador and Gary Shapiro of the American Statistical Association, developed a multi-stage random sample of the archive to get a clearer picture of its contents. Sampled documents shed light on the disappearance of Guatemalan union leader Edgar Fernando García who vanished in 1984 while in police custody. Expert testimony by Guzmán provided key evidence in the 2010 conviction of two former police officers who were found guilty of disappearing and murdering García.


Guzmán’s testimony was based on three years of coding key variables from random probabilistic samples of the archive that allowed him to make estimates about the contents of all the documents. Through his analysis, Guzmán was able to compare the percentage of documents about García known by different police units and supported the prosecution’s argument that high-level officers were involved in his disappearance. Guzmán’s statistical analysis of command responsibility provided critical information used to support the arrest of the former commander of the Guatemalan National Police and another senior police officer accused of complicity in García’s disappearance. HRDAG data will be used as evidence in these trials as well as in the prosecution of former senior army officials and former Guatemalan president Efraín Ríos Montt who are accused of genocide against indigenous people.

Our work has been used by truth commissions, international criminal tribunals, and non-governmental human rights organizations. We have worked with partners on projects on five continents.