Sex and Stature Estimation from Scapular Measurements: Development and Independent Validation in Northeastern Thai Population

Background/Objectives: Determination of the biological profile, particularly sex and stature, constitutes an essential component for individual identification in forensic and archaeological anthropology; however, validation of anthropometric equations remains inadequately implemented in contemporary research. This study addresses two limitations: the isolated development of sex and stature estimation methods and the lack of rigorous validation using independent samples. Methods: In this research, we analyzed 400 well-preserved scapulae from a Northeastern Thai population divided into training (n = 300: 150 male scapulae, 150 female scapulae) and validation (n = 100: 50 male scapulae, 50 female scapulae) groups. Eight standardized measurements were used for both sex and stature estimation. Results: All measurements demonstrated significant sexual dimorphism, with males exhibiting larger dimensions. For sex estimation, a multivariate model incorporating the maximum scapular height, maximum length of the spine, and scapula weight achieved 96.3% accuracy in the training samples and maintained 95.0% accuracy in independent validation. For stature estimation, a three-variable equation combining scapula weight, longitudinal scapular length, and maximum scapular breadth was strongly correlated (R = 0.769, SEE = 5.32 cm) with consistent performance across validation samples. Conclusions: Validation testing confirmed the high accuracy, reliability, and stability of both equations when applied to independent samples, with no significant differences in performance metrics between training and validation groups. These validated equations provide reliable standards for forensic practitioners analyzing scapular remains in practical applications within the northeastern Thai population.