Work

Technical Note: Reliability of Pöch’s facial shape classification system: A morphometric approach

Year: 2025

Type: article

Abstract: A standardized vocabulary of facial characteristics is essential in forensic anthropology for identifying both living and deceased individuals. Pöch’s facial shape classification system is widely used for this purpose, but its reliability has not been critically evaluated. This is particularly important as the system was originally developed based on European male populations, and prior research suggests that classification systems can be prone to observer inconsistencies. In this study, we evaluate the representativeness and reliability of Pöch’s system in describing face shape variation within a Mexican sample (n = 973). First, using geometric morphometrics and principal component analysis, we evaluated how well the system’s categories capture the observed facial diversity. Sixteen observers then classified 60 randomly selected faces twice using Pöch’s system, and we computed Fleiss’ Kappa and Cohen’s Kappa to assess intra- and inter-observer agreement. The level of consensus among observers was also measured by calculating the proportion of agreement for each facial shape. Our findings revealed significant morphological redundancy among most of Pöch’s categories, poor agreement within (mean Cohen’s Kappa = 0.203) and between (mean Fleiss’ Kappa = 0.112) observers, and only the round and oval categories showed high levels of consensus. Given the system’s poor performance, we conducted a post-hoc k-means clustering analysis of the Procrustes coordinates to explore a more representative classification scheme. The resulting four facial shape categories could inform the development of more representative and reliable classification systems. • This study evaluates the validity of Pöch’s face shape categories. • Quanti- and qualitative descriptions are used to assess their representativeness and reliability. • The findings reveal redundancy and low representativeness in Pöch’s categories. • Morphometrically distinct categories show higher inter-observer agreement. • We propose four categories to guide the development of representative classification systems.

Source: Forensic Science International

DOI: 10.1016/j.forsciint.2025.112435

Authors: Jocelyn Valladares, Daniel Antonio Lopez-Valdes, Arodi Farrera

Institutions: Universidad Nacional Autónoma de México, Instituto de Investigaciones Antropológicas

Language: English

Topic: Forensic Anthropology and Bioarchaeology Studies

Subfield: Archeology

Field: Arts and Humanities

Domain: Social Sciences

Open Access status: hybrid

Estimated APC paid: $4,580

Funder: Dirección General de Asuntos del Personal Académico, Universidad Nacional Autónoma de México