Empirically observed and predicted estimates of chance association: Estimating the chance association of randomly acquired characteristics in footwear comparisons.

The power associated with demonstrating a linkage between footwear and an impression left at the scene of a crime is directly related to the perceived rarity of the shoeprint itself. When individualizing characteristics are present, their relative position, orientation, size and shape are examined and compared with known exemplars to establish the strength of the suspected linkage. However, the degree to which a feature might repeat by chance alone is less well documented in many pattern science fields, including forensic footwear analysis.

Quantitative assessment of similarity between randomly acquired characteristics on high quality exemplars and crime scene impressions via analysis of feature size and shape.

Forensic footwear evidence can prove invaluable to the resolution of a criminal investigation. Naturally, the value of a comparison varies with the rarity of the evidence, which is a function of both manufactured as well as randomly acquired characteristics (RACs). When focused specifically on the latter of these two types of features, empirical evidence demonstrates high discriminating power for the differentiation of known match and known non-match samples when presented with exemplars of high quality and exhibiting a sufficient number of clear and complex RACs.

Quantifying randomly acquired characteristics on outsoles in terms of shape and position.

Footwear evidence has tremendous forensic value; it can focus a criminal investigation, link suspects to scenes, help reconstruct a series of events, or otherwise provide information vital to the successful resolution of a case. When considering the specific utility of a linkage, the strength of the connection between source footwear and an impression left at the scene of a crime varies with the known rarity of the shoeprint itself, which is a function of the class characteristics, as well as the complexity, clarity, and quality of randomly acquired characteristics (RACs) available for analysis. To help elucidate the discrimination potential of footwear as a source of forensic evidence, the aim of this research is to further characterize the chance association in position, shape, and geometry of RACs on a semi-random selection of footwear.