Collection-Specific Sample Bias in United States-Based Documented Skeletal Collections

Documented skeletal collections provide many of the samples necessary for forensic anthropological research, including the creation and validation of skeletal analytical methods. Although modern collections are considered more representative of the current living population, they often differ significantly from each other by geographic location, organization, and procurement strategies. As these factors influence which donors are included in a particular collection, they also create collection-specific sample bias. This research aims to identify how that bias impacts skeletal variation across collections and whether it obscures normal patterns of human skeletal variation. Craniometric and demographic data were collected from a sample of individuals from eight modern United States-based documented skeletal collections (n = 1161). The results indicate that collection-specific sample bias influences average cranial morphology, but to a lesser extent than sex or population. Across analyses, samples consistently and preferentially clustered with individuals from similar population and sex groups rather than with individuals from the same collection of origin. These analyses suggest that normal patterns of human variation are not obscured by collection origin and that documented skeletal collections therefore remain valid and reliable sources of data for understanding population diversity and sex differences, even when some level of collection-specific bias is present.