Assessing the accuracy of Transition Analysis 3.0 for estimating age in a Black SouthAfrican sample

Abstract

Age estimation is a complex part of the biological profile, influenced by various traits across the skeleton. The topic of combining multiple methods for estimating age is extensively debated, but the vitality of multifactorial age estimation methods is acknowledged. Transition analysis attempts to solve this problem using Bayesian statistics, particularly to avoid the effects of age mimicry. This study assessed the validity of Transition Analysis 3.0 (TA3) for the age estimation of black South Africans in a forensic context. The study sample consisted of the skeletal remains of 89 (44 females and 45 males) black South African individuals aged 15 to 105 years. This research assessed the validity of TA3 on dry bone via the analysis of trait-age correlations, sex-related and side-related differences, the correlation between true and estimated age, accuracy, inaccuracy, bias, and the effect of missing data. None of the traits correlated strongly with age, but estimates improved when poorly correlated traits were removed from the analysis. There were significant sex-related differences and significant asymmetry in bony dimensions and the scoring of the pubic symphysis. The average accuracy was approximately 70%, with the highest accuracies observed in individuals aged 35-84 years. The lowest bias and inaccuracy were observed in middle-aged individuals, but adolescents and young adults were over-estimated, and older adults were under-estimated. No significant difference in the predictive capability was noted when full regions of traits were removed. The low repeatability of some traits may be related to the fact that numerous traits used in TA3 are rarely used in age estimation, so practitioners are inexperienced in assessing them. The sex-related differences are consistent with the literature, but the findings of asymmetry in the pubic symphyseal traits are important to note. Problems related to accuracy, including the attraction to the middle, are likely related to the contents of the reference sample. In the case of TA3, the reference sample is primarily European-American and has a minimal representation of black African individuals. TA3 requires further revision of the included traits and substantial expansion of the reference sample, particularly emphasising non-European-American samples. Additionally, further testing in other South African populations is required before its use in South African a forensic context. iv This study showed that TA3 is neither reliable nor accurate enough for use in a South African forensic context and that the correlations between trait score and age are moderate at best. This study also highlighted problems with the methodology, software, and statistics.