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Forensic Footwear Reliability: Part II - Range of Conclusions, Accuracy, and Consensus

NCJ Number
Date Published
September 2020
12 pages
This article, the second of a three part series, presents the findings of a reliability study that assessed the extent of agreement between forensic footwear examiners in the United States.
Between February 2017 and August 2018, West Virginia University conducted a reliability study to determine expert performance among forensic footwear examiners in the United States. Throughout the study’s duration, 70 examiners each performed 12 comparisons and reported a total of 840 conclusions. In order to assess the accuracy of conclusions, the similarities and differences between mated and non-mated pairs were evaluated according to three criteria: (i) inherent agreement/disagreement in class, wear, and randomly acquired features; (ii) limitations as a function of questioned impression quality, clarity, and totality; and (iii) adherence to the Scientific Working Group for Shoeprint and Tire Tread Evidence (SWGTREAD) 2013 conclusion standard. Using these criteria, acceptable/expected categorical conclusions were defined. Preliminary results from this study are divided into a series of three summaries. This manuscript (Part II) reports accuracy and reproducibility. For mated pairs, accuracy equals 76.3 percent +/- 13.0 percent (median of 78.6 percent, and a 90 percent confidence interval between 72.2 percent and 80.0 percent). For non-mated pairs, accuracy equals 87.4 percent +/- 9.24 percent (median of 91.4 percent and a 90 percent confidence interval between 84.7 percent and 89.8 percent). In addition, the community assessed agreement (denoted by IQR) of reported results equals the research team’s accepted/expected conclusions for 10 out of 12 comparisons. In terms of reproducibility, the 90 percent confidence interval for consensus was computed and found to equal 0.71–0.86 (median of 0.77) for the combined dataset. Although based on a limited sample size, these results provide a baseline.
Date Published: September 1, 2020