Analysis Of Transitions Research Articles

The Effects of Physiological Stress on the Accuracy of Age-at-Death Estimation in The Hamann–Todd Collection

Age-at-death estimation is influenced by biological and environmental factors. Physiological stress is intertwined with these factors, yet their impact on senescence and age estimation is unknown. Stature, linear enamel hypoplasia (LEH), and antemortem tooth loss (AMTL) in the Hamann–Todd Osteological Collection (n = 297) are used to understand whether physiological stress is related to age estimation inaccuracy using transition analysis (TA). Considering the low socioeconomic status of individuals in the collection, it was expected that many people experienced moderate to severe physiological stressors throughout their lives. Of the sample, 44.1% had at least one LEH, but analyses found no relationship between LEH incidence and TA error. There was no association between stature and TA error for males or females. However, females with at least one LEH had significantly shorter statures (t = 2.412, p = 0.009), but males did not exhibit the same pattern (t = 1.498, p = 0.068). Further, AMTL frequency and TA error were related (r = 0.276, p < 0.001). A partial correlation controlling for age-at-death yielded a correlation coefficient of 0.024 (p = 0.684), suggesting that this relationship is mostly explained by age-at-death. These data suggest that age estimation methods are not significantly affected by physiological stress in this sample, but further investigations are needed to understand how these variables relate to skeletal aging.

The accuracy of age estimation using transition analysis in the Hamann-Todd collection.

Reconstructing demography of past populations using skeletal data is challenging when analyzing adults because the process of biological aging does not always reflect the individual's chronological age. A proposed solution to address the limitations of traditional age estimation methods is transition analysis (TA), a multifactorial method of age estimation. However, despite its methodological refinement, TA has varying degrees of accuracy when applied to different known-age skeletal samples. This study assesses TA's accuracy by comparing age estimates to known age at death in the Hamann-Todd Collection. We contrasted the maximum likelihood age estimates generated by the ADBOU program to the known ages of 221 individuals. The absolute error was calculated for the entire sample, and compared between sex and ancestry. The mean absolute error in the sample is 11.6 (SD = 10.3) years, with white individuals' errors (14.1 years) being significantly higher than black individuals' (9.1 years; p < 0.001). No significant differences were found between sexes (p = 0.621). A weak to moderate positive correlation was found between known age and absolute error for white males (R = 0.607; p < 0.001), white females (R = 0.509; p < 0.001), and black males (R = 0.371; p = 0.006). The accuracy of TA age estimates varied when each anatomical region was analyzed independently, but the combination of all three anatomical regions yielded the most accurate age estimates. These findings further support that TA accuracy depends on the prior distribution used and, in the Hamann-Todd Collection, the accuracy for white individuals is more influenced by this limitation than when black individuals are analyzed.

New Approaches to Age Estimation Using Palatal Suture Fusion.

Palatal suture fusion has seen little testing and/or application due in part to an inadequately described relationship to formal age ranges. This study presents a modified scoring method that examines fusion on samples of modern documented adult males and compares two Bayesian approaches to age estimation. In the first analysis, American and Portuguese collections were used to derive univariate and multivariate transition analysis (TA) parameters, which combined with an informative prior, estimated age in a sample of modern Americans and Portuguese. For the second analysis, a Bayesian multiple linear regression (BMLR) used indicator statuses as the independent variables with age as the dependent variable. Highest posterior density regions (HPDRs) and highest posterior density intervals (HDI) were calculated for a holdout sample. Final age estimates for the methods were tested for accuracy using cumulative binomial tests at 75% and 90% coverages. The HPDRs from multivariate TA captured age better for younger individuals, but consistently underaged. The cumulative binomial tests on the BMLR results indicated the prediction intervals performed as expected, and we show they are narrower (more precise) and/or more accurate than the corresponding HPDR. The modified method presented here formally links palatal suture obliteration to age using two different approaches, one of which (BMLR) is new to the aging literature. The BMLR provided results free from bias and more reasonable age ranges while maintaining accuracy. We present a look-up table and a free, simple R file for users to download and run their own estimates with BMLR.

The use of transition analysis in skeletal age estimation

AbstractThe ability to produce accurate and precise age‐at‐death estimates from adult skeletal remains is critical for both forensic and bioarchaeological analyses. Despite many decades of investigation, anthropologists are still heavily reliant on methods that fail to adequately capture biological variation in skeletal aging and produce estimates that are insufficient for most applications. The Transition analysis (TA) by Boldsen et al. (2002) refers to a broad category of statistical approaches used to generate probabilistic information from binary or ordinal reference data as well as a specific method, Transition Analysis (TA) (Boldsen et al. 2002), that combines components of the cranial sutures and pelvic joints. The TA method uses free software to generate age estimates from the available trait scores, a statistical correction for the use of correlated features, and information about population mortality structure. Variations of the transition analysis approach have also applied to data from traditional age‐estimation methods, isolated areas of the skeleton, and many features distributed throughout the body. Investigations of TA and other transition analysis‐based approaches on archaeological, historic, and modern remains have demonstrated significant improvements in our ability to document skeletal variation, produce estimates in the upper half of the adult lifespan, and investigate patterns of mortality in the past. Despite these improvements, several challenges remain, including wide age intervals and systematic age‐estimation bias, particularly for individuals in the youngest and oldest portions of adulthood. Moving forward, component‐based approaches capable of producing individualized, probabilistic estimates using new skeletal features and user‐friendly software are needed.This article is categorized under: Forensic Anthropology &gt; Age Assessment

Transition analysis applied to third molar development in a Danish population

IntroductionAge assessment based on dental development is often requested in order to assess whether an individual is older or younger than 18 years of age. There are several statistical approaches to estimate age based upon third molar development. The aim of this study was to apply the principles of transition analysis (TA) to a Danish reference material and to evaluate whether it was indicated to include a model that allows for logistic non-linearity as opposed to applying a model only allowing for logistic linearity. For this we chose to use the generalized additive model (gam) and the generalized linear model (glm), respectively. Material and methodA cross-sectional sample comprising 1302 panoramic radiographs of Danish subjects in the chronological age range of 13–25 years was included. All present third molars had been scored according to the 10-stage method of Gleiser and Hunt. Each transition from one stage to the subsequent stage was analyzed according to the statistical approach of TA and fitted with both the generalized linear model (glm) and the generalized additive model (gam). In order to assess whether gam or glm was more parsimonious for each transition individually, the Akaikon information criterion (AIC) was applied. ResultsThe results emphasized the importance of applying a statistical model that sufficiently captures the spread of the age estimate. The AIC values showed that some transitions were sufficiently described by glm whereas for others the gam curves fitted significantly better. ConclusionWe recommend that for an age assessment tool based on TA, both a fitting allowing for non-linearity and one allowing only for linearity should be included.

The accuracy of the Transition Analysis of aging on a heterogenic South African population

Transition Analysis (TA) is an age estimation method for adult skeletons at death, using three skeletal traits together, namely, the cranial sutures (CS), the pubic symphyses (PS) and the auricular surfaces (AS). In forensic anthropology, estimating age at death is vital for positive identification of an individual; however, differences in skeletal elements have been observed between sex and population affinity. The aim of this study was to determine how accurately the TA could be applied to a population that differed from the original reference samples.Scoring methods, described by the authors of this analysis, were used to age individuals (n = 290) in the South African (SA) Mixed Ancestry population, which is a heterogenic population, consisting of many gene pools from different population groups. The results were compared to the actual ages of the skeletal remains, obtained through cadaver records, and the most likely age calculated by the TA, as well as age estimation by means of the three skeletal elements individually.Results showed that there was a significant correlation between the actual and estimated ages of the study population (Pearson correlation coefficient: 0.58). The AS was the most accurate trait, whereas the PS was the least accurate trait. In addition, females’ estimated ages were more accurate than males. These findings correlated with other authors in terms of the significance of the TA when applied to different populations; however, the individual trait correlations were in disagreement with other authors. The results of this study are an important contribution to anthropological literature as they indicate that there are differences between populations and sex when determining age, but that the TA is still applicable for analysis on this heterogenic population.

Age Estimation in a Colombian Modern Skeletal Sample: A Test of the Transition Analysis Method

This research tested the ability of the transition analysis (TA) method to return accurate and precise age-at-death estimates in a sample of 58 skeletons from the Antioquia Modern Skeletal Collection. Contributions from individual structures (cranial sutures, pubic symphysis, and auricular surface) and combined structures to final age estimates were examined. When single anatomical structures were considered, the pubic symphysis provided the best age estimates, but results improved when all anatomical units were combined. Results from Pearson correlation tests (p < 0.001) indicated a strong correlation between estimated and chronological age. However, bias and inaccuracy values indicated that TA did not perform equally well for all age cohorts; the method worked better for late adolescents and young adults in the second decade of life and appeared to perform relatively well for individuals in the third decade, but not as satisfactorily. In contrast, results from middle-aged individuals were biased by small sample sizes. Estimates for old individuals were promising, as interval lengths decreased in comparison to those provided by foreign phase-based methods currently applied in Colombia. Gwet’s AC1 coefficients to evaluate interobserver reliability and agreement indicated that there was fair to good agreement in the majority of the traits scored, and discrepancies between examiners were likely due to differences in experience with the application of the method and/or problems with descriptions in English that do not translate well into Spanish. Thus, the translation of the method into Spanish is highly encouraged for a more consistent application of the method.

Testing inter‐observer reliability of the Transition Analysis aging method on the William M. Bass forensic skeletal collection

Skeletal age estimation is an integral part of the biological profile. Recent work shows how multiple-trait approaches better capture senescence as it occurs at different rates among individuals. Furthermore, a Bayesian statistical framework of analysis provides more useful age estimates. The component-scoring method of Transition Analysis (TA) may resolve many of the functional and statistical limitations of traditional phase-aging methods and is applicable to both paleodemography and forensic casework. The present study contributes to TA-research by validating TA for multiple, differently experienced observers using a collection of modern forensic skeletal cases. Five researchers independently applied TA to a random sample of 58 documented individuals from the William M. Bass Forensic Skeletal Collection, for whom knowledge of chronological age was withheld. Resulting scores were input into the ADBOU software and maximum likelihood estimates (MLEs) and 95% confidence intervals (CIs) were produced using the forensic prior. Krippendorff's alpha was used to evaluate interrater reliability and agreement. Inaccuracy and bias were measured to gauge the magnitude and direction of difference between estimated ages and chronological ages among the five observers. The majority of traits had moderate to excellent agreement among observers (≥0.6). The superior surface morphology had the least congruence (0.4), while the ventral symphyseal margin had the most (0.9) among scores. Inaccuracy was the lowest for individuals younger than 30 and the greatest for individuals over 60. Consistent over-estimation of individuals younger than 30 and under-estimation of individuals over 40 years old occurred. Individuals in their 30s showed a mixed pattern of under- and over-estimation among observers. These results support the use of the TA method by researchers of varying experience levels. Further, they validate its use on forensic cases, given the low error overall.

Age estimation in the living: Transition analysis on developing third molars

A radiographic assessment of third molar development is essential for differentiating between juveniles and adolescents in forensic age estimations. As the developmental stages of third molars are highly correlated, age estimates based on a combination of a full set of third molar scores are statistically complicated. Transition analysis (TA) is a statistical method developed for estimating age at death in skeletons, which combines several correlated developmental traits into one age estimate including a 95% prediction interval. The aim of this study was to evaluate the performance of TA in the living on a full set of third molar scores. A cross sectional sample of 854 panoramic radiographs, homogenously distributed by sex and age (15.0–24.0 years), were randomly split in two; a reference sample for obtaining age estimates including a 95% prediction interval according to TA; and a validation sample to test the age estimates against actual age. The mean inaccuracy of the age estimates was 1.82 years (±1.35) in males and 1.81 years (±1.44) in females. The mean bias was 0.55 years (±2.20) in males and 0.31 years (±2.30) in females. Of the actual ages, 93.7% of the males and 95.9% of the females (validation sample) fell within the 95% prediction interval. Moreover, at a sensitivity and specificity of 0.824 and 0.937 in males and 0.814 and 0.827 in females, TA performs well in differentiating between being a minor as opposed to an adult. Although accuracy does not outperform other methods, TA provides unbiased age estimates which minimize the risk of wrongly estimating minors as adults. Furthermore, when corrected ad hoc, TA produces appropriate prediction intervals. As TA allows expansion with additional traits, i.e. stages of development of the left hand-wrist and the clavicle, it has a great potential for future more accurate and reproducible age estimates, including an estimated probability of having attained the legal age limit of 18 years.

Reshaping Urban Infrastructure

SummaryUrban policy makers and researchers consistently recognize the challenge of more effectively reshaping the linkages between cities, urban infrastructure, ecosystem services, and natural resources. The aim of this article is to consider the potential value of developing connections between two currently disconnected approaches to resource use and cities—material flow analysis (MFA) and transitions analysis (TA). This article attempts to address this deficit and looks critically at resource flows through cities and the infrastructures that have been—or could be—reconfigured to more effectively manage these flows from the perspectives of MFA and TA. This is an issue that has not been addressed, with the result that inadequate attention has been paid to the reconfiguring of urban infrastructures whose construction and maintenance are, in turn, often the largest expenditures at the city government level. Insufficient attention has been given to the fact that the design, construction, and operation of infrastructures (specifically energy, waste, water, sanitation, and transport infrastructures) create a sociotechnical environment that plays an important role in shaping, and potentially reshaping, how resources are procured, used, and disposed of by the city. The challenge, of course, is how such a transition takes place, who leads it and what social and governance processes are best suited to facilitate such city transitions. This article assesses the role of MFA and TA in understanding these resource flows and urban infrastructures, making it possible to begin to tackle this challenge in practical transformative ways.