Accuracy Rates of Ancestry Estimation by Forensic Anthropologists Using Identified Forensic Cases

Abstract

A common task in forensic anthropology involves the estimation of the ancestry of a decedent by comparing their skeletal morphology and measurements to skeletons of individuals from known geographic groups. However, the accuracy rates of ancestry estimation methods in actual forensic casework have rarely been studied. This article uses 99 forensic cases with identified skeletal remains to develop accuracy rates for ancestry estimations conducted by forensic anthropologists. The overall rate of correct ancestry estimation from these cases is 90.9%, which is comparable to most research-derived rates and those reported by individual practitioners. Statistical tests showed no significant difference in accuracy rates depending on examiner education level or on the estimated or identified ancestry. More recent cases showed a significantly higher accuracy rate. The incorporation of metric analyses into the ancestry estimate in these cases led to a higher accuracy rate.

Uncloaking a Lost Cause: Decolonizing ancestry estimation in the United States

“…3.2 | Does ancestry estimation really "work"? Thomas et al (2017) tout ancestry estimation success based on their comparison of identified cases to the corresponding forensic anthropological analyses. However, arguments such as this use circular logic because positively identified cases are known.…”

Evaluating population affinity estimates in forensic anthropology: Insights from the forensic anthropology database for assessing methods accuracy (FADAMA)

“…We utilized the Freeman-Halton extension of Fisher's exact test to assess whether accuracy results were statistically significantly different for different variables [23,24]. This protocol generally followed Thomas et al [17] in order to enable direct comparisons between the two studies. However, the first variable examined in the FBI study, educational level of the analyst, was not available in the FADAMA dataset.…”

“…However, differences in accuracy among the groups were not statistically significant (p = 0.113-0.161). When accuracies were assessed by estimated ancestry, in order to assess whether certain ancestries were more likely to be incorrectly classified, all ancestries were a Please note that in this and the following tables, we chose to present group names alphabetically rather than following the presentation of Thomas et al [17] While following [17] would have maximized comparability of our data with the FBI data, we wished to eschew an arrangement which seems to list "White/European" first by default.…”

“…In a 2017 study, Thomas et al [17] evaluated accuracy rates of forensic anthropological ancestry estimation using a sample of 99 identified skeletal cases analyzed at the Federal Bureau of Investigation (FBI) Laboratory. In the current study, we provide an update to these findings, utilizing a large sample of anonymized, identified cases previously evaluated by forensic anthropologists in order to quantify estimation error both overall and in group-specific contexts.…”

Commentary on: Bethard JD, DiGangi EA. Letter to the Editor—Moving beyond a lost cause: Forensic anthropology and ancestry estimates in the United States. J Forensic Sci. 2020;65(5):1791–2. doi: 10.1111/1556‐4029.14513.

“…Importantly, the same morphological features could also be used to classify groups defined by language, nationality, or time period because those are all features that structure populations [9][10][11][12]. Research has assessed accuracy rates of ancestry estimations by forensic anthropologists and reported correct ancestry estimates at 90.9% [13]. Contra to Bethard and DiGangi, these results highlight the strong concordance between genomic ancestry and self-reported race/ethnicity in the United States [14][15][16].…”