Do group-specific equations provide the best estimates of stature?

An estimate of stature can be used by a forensic anthropologist with the preliminary identification of an unknown individual when human skeletal remains are recovered. Fordisc is a computer application that can be used to estimate stature; like many other methods it requires the user to assign an unknown individual to a specific group defined by sex, race/ancestry, and century of birth before an equation is applied. The assumption is that a group-specific equation controls for group differences and should provide the best results most often. In this paper we assess the utility and benefits of using group-specific equations to estimate stature using Fordisc. Using the maximum length of the humerus and the maximum length of the femur from individuals with documented stature, we address the question: Do sex-, race/ancestry- and century-specific stature equations provide the best results when estimating stature? The data for our sample of 19th Century White males (n=28) were entered into Fordisc and stature was estimated using 22 different equation options for a total of 616 trials: 19th and 20th Century Black males, 19th and 20th Century Black females, 19th and 20th Century White females, 19th and 20th Century White males, 19th and 20th Century any, and 20th Century Hispanic males. The equations were assessed for utility in any one case (how many times the estimated range bracketed the documented stature) and in aggregate using 1-way ANOVA and other approaches. This group-specific equation that should have provided the best results was outperformed by several other equations for both the femur and humerus. These results suggest that group-specific equations do not provide better results for estimating stature while at the same time are more difficult to apply because an unknown must be allocated to a given group before stature can be estimated.

Do century-specific equations provide better estimates of stature? A test of the 19-20th century boundary for the stature estimation feature in Fordisc 3.0.

A sample (n=28) from the Terry Collection was selected to include only White males who were born and had their entire growth and development period before 1900 to assess the effects year of birth have on accuracy and precision when estimating stature. Using the computer application Fordisc 3.0, stature was estimated using the humerus, radius, femur, and tibia equations developed from White males born in the 19th Century and the 20th Century. The 19th Century White male equations did not consistently provide the most precise and accurate estimates of stature. The 20th Century equations provide results that were as good as or slightly better than the 19th Century equations for the humerus, radius and femur. The 20th Century equations provided notably better results for the tibia. There is a great deal of evidence that there are clear positive secular changes in most of North America in the last 100-125 years, but the division commonly advocated in a forensic context at the year 1900 has no positive effect on accuracy or precision when estimating stature.