Quantitative Statistics and Identification of Tool‐Marks

Yang, Min; Li, Mou; Fu, Yiming; Wang, Yu; Wang, Jiang‐feng

doi:10.1111/1556-4029.14040

Cited by 4 publications

(3 citation statements)

References 15 publications

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“…Since the publication of the PCAST report, a number of firearms examiners and independent researchers have conducted additional investigations dealing with various aspects of comparative examinations. These include the estimation of examiner error rates [ 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 ], statistical evaluation methods in the Identification of toolmarks [ 19 , 20 ], and efforts to produce either automated or computer‐based objective determinations [ 15 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 ]. Additionally, several compilations contain general discussions and document research efforts as applied to firearms and toolmark examinations [ 32 , 33 , 34 , 35 , 36 , 37 ].…”

Section: Introductionmentioning

confidence: 99%

Accuracy of comparison decisions by forensic firearms examiners

Monson

Smith

Peters

2022

Journal of Forensic Sciences

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This black box study assessed the performance of forensic firearms examiners in the United States. It involved three different types of firearms and 173 volunteers who performed a total of 8640 comparisons of both bullets and cartridge cases. The overall false-positive error rate was estimated as 0.656% and 0.933% for bullets and cartridge cases, respectively, while the rate of false negatives was estimated as 2.87% and 1.87% for bullets and cartridge cases, respectively. The majority of errors were made by a limited number of examiners. Because chi-square tests of independence strongly suggest that error probabilities are not the same for each examiner, these are maximum-likelihood estimates based on the beta-binomial probability model and do not depend on an assumption of equal examiner-specific error rates. Corresponding 95% confidence intervals are (0.305%, 1.42%) and (0.548%, 1.57%) for false positives for bullets and cartridge cases, respectively, and (1.89%, 4.26%) and (1.16%, 2.99%) for false negatives for bullets and cartridge cases, respectively. The results of this study are consistent with prior studies, despite its comprehensive design and challenging specimens.

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Section: Introductionmentioning

confidence: 99%

Accuracy of comparison decisions by forensic firearms examiners

Monson

Smith

Peters

2022

Journal of Forensic Sciences

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“…LCM utilizing a comparison microscope has been used for over a hundred years and remains the primary method of comparison for microscopic toolmarks present on fired ammunition components [1]. In the past decade, a large body of research has been conducted in firearm examination using emerging technology of 3‐dimensional (3D) surface topographies and computer comparison algorithms [2–11]. The use of 3D topographies is now termed Virtual Comparison Microscopy (VCM).…”

Section: Introductionmentioning

confidence: 99%

Results of the 3D Virtual Comparison Microscopy Error Rate (VCMER) Study for firearm forensics

Chapnick¹,

Weller²,

Duez³

et al. 2020

Journal of Forensic Sciences

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The digital examination of scanned or measured 3D surface topography is referred to as Virtual Comparison Microscopy (VCM). Within the discipline of firearm and toolmark examination, VCM enables review and comparison of microscopic toolmarks on fired ammunition components. In the coming years, this technique may supplement and potentially replace the light comparison microscope as the primary instrument used for firearm and toolmark examination. This paper describes a VCM error rate and validation study involving 107 participants. The study included 40 test sets of fired cartridge cases from firearms with a variety of makes, models, and calibers. Participants used commercially available VCM software which allowed digital data distribution, specimen visualization, and submission of conclusions. The software also allowed participants to annotate areas of similarity and dissimilarity to support their conclusions. The primary cohort of 76 qualified United States and Canadian examiners that completed the study had an overall false‐positive error rate of 3 errors from 693 comparisons (0.43%) and a false‐negative error rate of 0 errors from 491 comparisons (0.0%). This accuracy is supplemented by the participant's provided surface annotations which provide insight into the cause of errors and the overall consistency across the independent examinations conducted in the study. The ability to obtain highly accurate conclusions on test fires from a wide range of firearms supports the hypothesis that VCM is a useful tool within the crime laboratory.

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“…With a push for statistical data to accompany firearm and toolmark casework, there was a surprising void of papers that focused solely on non-firearm related toolmarks and statistics. The authors of this paper, however, did publish this article containing some interesting data related to statistical analysis in toolmarks [ 45 ]. The authors began with a thorough summary of previous research that involved statistical analysis on toolmarks as a reference point for the reader.…”

Section: Toolmarksmentioning

confidence: 99%