Sex estimation from first rib morphometrics of samples from central Thailand

Abstract Background Reliable estimation of biological sex is a fundamental aspect of human skeletal analysis and human identification. However, the pelvis, which traditionally provides the highest accuracy, is not always preserved or available for examination. The present study aimed to generate discriminant function equations for sex estimation using the first rib found in Central Thailand. The study analyzed a total of 100 samples, comprising 60 males and 40 females. Six morphometric parameters of the first rib were measured on both the left and right sides, and parameters showing significant sexual differences were selected for stepwise discriminant function analysis to generate side-specific and combined equations. Results The combined discriminant function equation, using both ribs, achieved 89% accuracy in the training samples and 88.0% in the cross-validation. Side-specific equations yielded 81.0–87.0% in the training samples and 81.0–85.0% in the cross-validation. Conclusion These results suggest that the first rib may serve as a useful alternative skeletal element for sex estimation in the population of Central Thailand. The discriminant equations developed in this study provide population-specific reference data and may offer a practical method for sex estimation.