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Testing Likelihood Ratios Produced From Complex DNA Profiles

NCJ Number
Date Published
March 2015
7 pages
This study investigated a number of diagnostics in assessing the performance of a model (Hd true tests) for testing likelihood ratios produced from complex DNA profiles.
The performance of any model used to analyze DNA profile evidence should be tested using simulation, large-scale validation studies based on ground-truth cases, or alignment with trends predicted by theory. The focus of the current work was the proportion of comparisons to non-contributors that yield a likelihood ratio (LR) higher than or equal to the likelihood ratio of a known contributor (LRPOI), designated as p, and the average LR for Hd true tests. Theory predicts that p should always be less than or equal to 1/LRPOI and hence the observation of this in any particular case is of limited use. A better diagnostic is the average LR for Hd true which should be near to 1. The current study tested the performance of a continuous interpretation model on nine DNA profiles of varying quality and complexity and verified the theoretical expectations. (Publisher abstract modified)

Date Published: March 1, 2015