An assessment of the accuracy of discriminant function equations for sex determination of the femur and tibia from a South African population.

The purpose of this study is to test the accuracy of seven discriminant function equations that have been derived by Steyn and Isçan for sex determination using measurements of the femur and tibia of South Africans of European descent (SAED). While the validity of some of the discriminant functions has been assessed by the authors who derived them, no previous independent study has been carried out to assess the accuracy of these equations. These equations have not been tested on skeletons located outside of the Gauteng province. A suite of measurements were taken on 272 femora and 256 tibiae obtained from four South African skeletal collections. The validity of each of the previously published equations for the femur was confirmed. However, two functions of the tibia showed low accuracy rates, most likely due to difficulties in recording the distal epiphyseal breadth measurement, and thus were found to be poor assessors of sex.

The skull and humerus in the determination of sex: reliability of discriminant function equations.

Sex determination plays a crucial role in the identification of human remains as it narrows the possibility for identification by 50%. The purpose of this study is to test the validity of five discriminant function equations, with accuracies of 80% and higher, that have been derived by Steyn and Iscan [M. Steyn, M.Y. Iscan, Sexual dimorphism in the crania and mandibles of South African Whites, Forensic Sci. Int. 98 (1998) 9-16; M. Steyn, M.Y. Iscan, Osteometric variation in the humerus: sexual dimorphism in South Africans, Forensic Sci. Int. 106 (1999) 77-85] for the skull and humerus of South Africans of European Descent (SAED). These equations were tested on different regional populations of SAED within South Africa. While the validity of some of the discriminant functions has been assessed by the authors who derived them, no other previous independent study has been carried out to assess the reliability of these equations. In addition, these equations have not been tested on skeletons located outside the Gauteng province. The study sample consisted of 230 skulls and 264 humeri of SAED obtained from four South African skeletal collections: Raymond A. Dart Collection of Human Skeletons (Johannesburg); Pretoria Bone Collection; Cape Town Skeletal Collection; and the Osteology Archive Student Collection (Stellenbosch). A total of 14 measurements (12 cranial and 2 humeral) were taken on these skeletal elements. The observed accuracies from the present study (72.0-95.5%), with the exception of one sample's accuracy, compared well with the original classification rates (80.2-92.5%) for most of the functions thereby confirming the validity of the discriminant function equations for sex determination for the skull and humerus of SAED, for SAED in all regions of South Africa.