Response to "Likelihood Ratio as Weight of Evidence: A Closer Look" by Lund and Iyer

• NCJ Number: 253484
• Author(s): Simone Gittelson; Charles E.H. Berger; Graham Jackson; Ian W. Evett; Christop;he Champod; Bernard Robertson; James M. Curran; Duncan Taylor; Bruce S. Weir; Michael D. Coble; John S. Buckleton
• Date Published: July 2018
• Length: 5 pages
• Grant Number(s): 2017-DN-BX-0136; 2015-DN-BX-K049
• Agencies: NIJ-Sponsored
• Publication Type: Research (Applied/Empirical); Report (Study/Research); Report (Grant Sponsored); Program/Project Description
• Award: Strengthening the evaluation and interpretation of glass evidence using statistical analysis of collection sets and databases of refractive index and elemental data (uXRF, ICP-MS and LA-ICP-MS); Population Genetic Issues for Forensic DNA Profiles

Annotation

This article challenges the recent argument presented by Lund and Iyer (L&I) regarding the use of likelihood ratios in court.

Abstract

The authors of the current article view L&I's argument as based on a misunderstanding of the paradigm. L&I argue that the decision maker should not accept the expert's likelihood ratio without further consideration. This is agreed by all parties. In normal practice, there is often considerable and proper exploration in court of the basis for any probabilistic statement. The current article concludes, however, that L&I argue against a practice that does not exist and which no one advocates. Further, the current article concludes that the most informative summary of evidential weight is the likelihood ratio. The authors state that this is the summary that should be presented to a court in every scientific assessment of evidential weight, with supporting information about how it was constructed and on what it was based. (publisher abstract modified)