How do class characteristics differ from random characteristics in physical evidence?

Class characteristics are features that allow items to be grouped together based on shared properties or traits. They are generalizations that apply to a category of objects rather than being specific to any one object. For example, the tread pattern on a particular model of tire can be considered a class characteristic because many tires of that model will share that tread design. In contrast, random characteristics are unique and can result from specific manufacturing processes, wear, damage, or other individual factors that apply to a specific item. These can include scratches, imperfections, or specific marks that are not found in other items, making them unique identifiers of a specific object.

The distinction lies in the ability of class characteristics to imply a commonality among a group, while random characteristics serve to link a specific piece of evidence with an individual item or source. Understanding this differentiation is crucial in forensic analysis, as class characteristics help establish connections among multiple pieces of evidence, whereas random characteristics may provide definitive links to an individual piece of evidence.