Statistical Issues in Forensic Science

Abstract

Forensic science refers to the use of scientific methods in a legal context. Several recent events, especially the release in 2009 of the National Research Council (NRC) report Strengthening Forensic Science in the United States: A Path Forward, have raised concerns about the methods used to analyze forensic evidence and the ways in which forensic evidence is interpreted and reported on in court. The NRC report identified challenges including the lack of resources in many jurisdictions compared with the amount of evidence requiring processing, the lack of standardization across laboratories and practitioners, and questions about the analysis, interpretation and presentation of evidence. With respect to the last, the NRC report raises questions about the underlying scientific foundation for forensic examinations on some evidence types. Statistics has emerged as a key discipline for helping the forensic science community address these challenges. The standard elements of statistical analysis—study design, data collection, data analysis, statistical inference, and summarizing and reporting inferences—are all relevant. This article reviews the role of forensic evidence, the heterogeneity of forensic domains, current practices and their limitations, and the potential contributions of more rigorous statistical methods, especially Bayesian approaches and the likelihood ratio, in the analysis, interpretation, and reporting of forensic evidence.