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Social and Behavioral Sciences Commons

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Forensic Science and Technology

City University of New York (CUNY)

Theses/Dissertations

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Full-Text Articles in Social and Behavioral Sciences

A 3d Characteristics Database Of Land Engraved Areas With Known Subclass, Entni Lin Jun 2018

A 3d Characteristics Database Of Land Engraved Areas With Known Subclass, Entni Lin

Student Theses

Subclass characteristics on bullets may mislead firearm examiners when they rely on traditional 2D images. In order to provide indelible examples for training and help avoid identification errors, 3D topography surface maps and statistical methods of pattern recognition are applied to toolmarks on bullets containing known subclass characteristics. This research was conducted by collecting 3D topography surface map data from land engraved areas of bullets fired through known barrels. This data was processed and used to train the statistical algorithms to predict their origin. The results from the algorithm are compared with the “right answers” (i.e. correct IDs) of the …


Bayesian Approach To Toolmark Analysis, Antonio W. Del Valle May 2017

Bayesian Approach To Toolmark Analysis, Antonio W. Del Valle

Student Theses

Statistical analysis of toolmarks using frequentist methods can be problematic for assorted reasons. Thus, in order to analyze toolmarks whilst avoiding these issues, a Bayesian approach is taken. Specifically for this thesis we discuss the computation of a specific Likelihood Ratio for toolmark comparisons. This Bayesian based approach involves using data already at hand in conjunction with a probability model in order to establish an estimate for its “value”, i.e. the “weight of evidence”. Making the calculations to obtain a Likelihood Ratio is very cumbersome and time consuming. Also many commercial software packages hide the process and underlying assumptions that …