Sex Estimation Models Research Articles

Sex estimation from the femur using discriminant function analysis in a Central Indian population.

Sexual dimorphism is one of the major factors responsible for apparent variations in human skeletal anatomy. Establishing the biological profile of the deceased is essential for personal identification in forensic and archaeological casework. To develop a reliable biological profile, sex allocation is an integral step required to determine age, race/ancestry and stature, given observable differences in aging and growth patterns and variations in morphological traits relating to ancestry. Sex estimation from long bones by visual examination is very difficult. However, metric observations are more objective and effective. This osteometric analysis focused on sex estimation from the femur using discriminant function analysis. Fourteen measurements were taken directly on 175 dry femora (117 males and 58 females), aged 20–60 years, from the Chhattisgarh region of Central India. Student’s t-test was applied to assess significant sex and size differences. Direct and stepwise discriminant function analyses were applied to derive discriminant function models for sex estimation. The three parameters that were selected for the discriminant function analysis included: transverse head diameter, bi-trochanteric distance and maximum shaft diameter. Males were more accurately classified than females. An overall accuracy of 80.6% was reported with direct discriminant function analysis and 76% with stepwise discriminant function analysis upon cross-validation. The transverse head diameter emerged to be the best predictor of sex. This study provides a database and standards for sex estimation from skeletal remains of an unknown nature based on discriminant function equations. This is one of the few studies conducted in India on dry bones, and we anticipate that it will guide forensic specialists in the identification of unknown skeletons from this region.

Sex estimation from handprints in a Croatian population sample

Aim: To test if handprint measurements show sexual dimorphism in the Croatian population, and to develop population-specific sex estimation standards. Methods: A cross-sectional study was conducted on 100 adult volunteers from a Croatian population (50 males and 50 females) aged between 20 and 45 years. Using a fingerprint ink, we collected handprints of both hands on a paper sheet. We scanned handprints and took 13 measurements. Bilateral asymmetry and sexual dimorphism of the measurements was analyzed and sex estimation models were developed using linear discriminant analysis. Results: All measurements exhibited statistically significant sexual dimorphism (P<0.001). Univariate discriminant functions provided sexing accuracy from 75% to 92%. The highest accuracy rate (92%) and the lowest sexing bias (0%) was obtained using the handprint breadth. A multivariate discriminant function could estimate sex with 93% accuracy, but with more pronounced sexing bias (10%). Conclusion: We showed that handprint measurements could be used for sex estimation in the Croatian population with a high accuracy level. Therefore, they could serve as a valuable tool for biological profiling of perpetrators in criminal investigations when other evidence is not conclusive.

An Analysis of Hounsfield Unit Values and Volumetrics from Computerized Tomography of the Proximal Femur for Sex and Age Estimation.

Sex and age are two elements in the establishment of a biological profile for forensic identification. While the pelvic bones are the most ideal structures for sex estimation, the condition of a body is not always ideal due to the nature of death, such as in mass disasters, or postmortem processes. This study utilized CT scans and resultant 3D models of 100 male and 100 female adults of known ages ranging from 18 to 98years old to collect volumetric and Hounsfield unit measurements of the proximal femur. Equations were created to establish logistic regression models for sex estimation and linear regression models for age estimation. The resultant sex estimation method had an accuracy of 93.5% and utilized the volume of the proximal femur. This study provides three linear regression models for age with an accuracy range of 86%-92% ±12years. As imaging technologies are increasingly adopted for forensic purposes, the power of 3D data will provide the opportunity for more quantitative and reproducible analyses. The proposed method for sex and age estimation provides a reliable tool that can be utilized in both day-to-day casework and disaster victim identification.

CADOES: An interactive machine-learning approach for sex estimation with the pelvis

The pelvis is consistently regarded as the most sexually dimorphic region of the human skeleton, and methods for sex estimation with the pelvic bones are usually very accurate. In this investigation, population-specific osteometric models for the assessment of sex with the pelvis were designed using a dataset provided by J.A. Serra (1938) that included 256 individuals (131 females and 125 males) from the Coimbra Identified Skeletal Collection and 38 metric variables. The models for sex estimation were operationalized through an online application and decision support system, CADOES. Different classification algorithms generated high accuracy models, ranging from 85% to 92%, with only three variables; and from 85.33% to 97.33%, with all 38 variables. CADOES conveys a probabilistic prediction of skeletal sex, as well as a suite of attributes with educational applicability in the fields of human skeletal anatomy and statistics. This study upholds the value of the pelvis for the estimation of skeletal sex and provides models for that can be applied with high accuracy and low bias.

Sex Estimation from Postcranial Measurements in Filipino Mortuary Remains

Filipino populations are under-studied in the field of forensic anthropology. The development of population-specific analyses for those of Filipino descent is critical in an increasingly globalized world with a growing diaspora of Filipino individuals. The objectives of this study are to broaden our knowledge of sexual dimorphism and to contribute to standard forensic methods.The sample consisted of 39 adult individuals (25 males and 14 females) of Filipino ancestry from the Manila North Cemetery in Manila, Philippines. Using this sample, discriminant function models for sex estimation that generated the highest separation power were generated. These models were cross-validated using a .632+ bootstrap method with 1,000 iterations. Humeral head diameter and anterior-posterior diameter of the radius produced the highest accuracy (>99%) for sex discrimination. Multivariate models were shown to be more powerful than univariate models. The results are discussed in the context of inter-population differences in sexual dimorphism.

Forensic anthropological standards for cranial sex estimation in Canada: preliminary results

ABSTRACTIn forensic investigations of unknown skeletal remains, a biological profile is used to narrow the pool of potential matches in the missing person’s database; one of the important components of that profile is the accurate estimation of skeletal sex. The current study involves the morphometric quantification of cranial sexual dimorphism in a Canadian population for the specific purpose of developing predictive models for the estimation of sex. The main aim of this study is, therefore, to quantify the accuracy methods of said existing sex estimation models as applied to a Canadian population and thereafter devise population-specific standards. The current study represents the retrospective analysis of 400 (190 female, 210 male) multiple detector computed tomography (MDCT) scans collected from the Sunnybrook Health Sciences Centre in Toronto, Ontario. Preliminary results indicate that current methods of cranial skeletal sex estimation illicit unacceptable classification accuracy rates when applied to this sample.

Estimation of sex and stature using anthropometry of the upper extremity in an Australian population.

Stature and a further 8 anthropometric dimensions were recorded from the arms and hands of a sample of 96 staff and students from the Australian National University and The University of Newcastle, Australia. These dimensions were used to create simple and multiple logistic regression models for sex estimation and simple and multiple linear regression equations for stature estimation of a contemporary Australian population. Overall sex classification accuracies using the models created were comparable to similar studies. The stature estimation models achieved standard errors of estimates (SEE) which were comparable to and in many cases lower than those achieved in similar research. Generic, non sex-specific models achieved similar SEEs and R2 values to the sex-specific models indicating stature may be accurately estimated when sex is unknown.

A Univariate Approach to Sex Estimation for the Fragmentary Upper Limb.

Although there are numerous reliable multivariate models for sex estimation, many scenarios, both forensic and archaeological, result in the recovery of fragmentary remains, which prevents the collection of various standard measurements. The purpose of this research was to establish metric applications for sex estimation from the distal humerus and distal radius of European/American Whites and American Blacks. Data for this research were retrieved from a sample consisting of a larger database from multiple skeletal collections. Measurements include epicondylar breadth, breadth of the capitulum-trochlea, and distal breadth of the radius. Student's t-test and descriptive statistics were utilized to analyze the data. Classification rates ranged from 75% to 96.4%, with the capitulum-trochlea breadth performing best. Overall, significant metric differences exist between the sexes in the distal humerus and radius and can be utilized to estimate sex. This study offers a reliable alternative sex estimation technique applicable to fragmentary or damaged remains.

Estimation of Sex From Index and Ring Finger Lengths in An Indigenous Population of Eastern India.

Forensic anthropology involves the identification of human remains for medico-legal purposes. Estimation of sex is an essential element of medico-legal investigations when identification of unknown dismembered remains is involved. The present study was conducted with an aim to estimate sex from index and ring finger lengths of adult individuals belonging to an indigenous population of eastern India. A total of 500 unrelated adult individuals (18-60 years) from the Rajbanshi population (males: 250, females: 250) took part in the study. A total of 400 (males: 200, 200 female) participants were randomly used to develop sex estimation models using Binary Logistic Regression Analysis (BLR). A separate group of 200 adults (18-60 years) from the Karbi tribal population (males 100, females 100) were included to validate the results obtained on the Rajbanshi population. The univarate and bivariate models derived on the study group (n=400) were tested on hold-out sample of Rajbanshi participants (n=100) and the other test population of the Karbi (n=200) participants. The results indicate that Index Finger Length (IFL) and Ring Finger Length (RFL) of both hands were significantly longer in males as compared to females. The ring finger was longer than the index finger in both sexes. The study successfully highlights the existence of sex differences in IFL and RFL (p<0.05). No sex differences were however, observed for the index and ring finger ratio. The predictive accuracy of IFL and RFL in sex estimation ranged between 70%-75% (in the hold out sample from the Rajbanshi population) and 60-66% (in the test sample from the Karbi population). A Receiver Operating Curve (ROC) analysis was performed to test the predictive accuracy after predicting the probability of IFL and RFL in sex estimation. The predicted probabilities using ROC analysis were observed to be higher on the left side and in multivariate analysis. The study concludes that sex estimation from index and ring finger lengths could be of utility when more reliable means of sex estimation are not available during medico-legal investigations.

Sexual dimorphism in cranial morphology among modern South Africans.

Pattern expressions of morphoscopic cranial traits vary across populations with classification accuracies being highly dependent on the reference collection to which unknown skulls are compared. Despite recent developments in population-specific standards for South Africans, researchers have not addressed the accuracy of morphological methods. Several studies demonstrate differences in sexual dimorphism between South Africans and North Americans, warranting a need to re-evaluate sex estimation methods in South Africa. The purposes of this study were to test the reliability and accuracy of the Walker (2008) method and to examine patterns of sexual dimorphism among South Africans. A total of 245 modern Black and White South African male and female crania from the Pretoria Bone Collection, University of Pretoria, were scored using the Walker (2008) methodology. Cohen's kappa was used to evaluate reliability of the method, and percent correct assessed validity of the method. Logistic regression was utilised to create modified population-specific formulae. Inter- and intra-observer agreement was moderate to excellent (0.60-0.90), except for the mental eminence (0.40). The percent correct results for sex were 80% or higher for combinations of glabella, mastoid and menton and between 68% and 73% for menton, mastoid, orbital and nuchal margin using logistic equations of Walker (2008). White males had the highest (94-97%) and White females had the lowest (31-62%) percent correct. The low accuracies obtained when using Walker's (2008) equations emphasised the need for population-specific sex estimation models. Modified formulae for South Africans were created, yielding higher classification rates (84-93%) than when North American standards were employed.