Patterns in the Phenice (1969) and Klales et al. (2012) methods of sex estimation using forensic casework from the United States

Sex estimation methods from the pelvis have been well-studied in research settings to estimate accuracy, error, and bias. However, patterns in casework are minimally described. We uniquely examine forensic anthropology casework in the United States retrospectively for the Phenice and Klales et al.'s sex estimation methods. Our hypothesis is that casework patterns will reflect the greater literature derived from research settings that show Phenice's method is more accurate and has lower error and sex bias. We use the publicly available Forensic Anthropology Database for Assessing Methods Accuracy. A sample of 229 cases from the United States reported the outcomes of applying these methods. McNemar's tests evaluate whether estimated sex is consistent with documented sex, and a Fisher's exact test compared the performance of the two methods. We further calculated accuracy, error, and sex biases of the methods. The McNemar's and Fisher's exact tests were not statistically significant, which indicates that both methods estimated sex at a rate close to the documented sex and to each other. Phenice's method displayed an accuracy of 99.4%, an error of 0.6%, and a sex bias of -2.4%. Alternatively, the Klales et al.'s method performed slightly lower with a 97.5% accuracy, 2.5% error, and 3.5% sex bias. Forensic anthropology casework in the United States reflects broader patterns in accuracy, error, and bias in the research setting literature, where Phenice outperforms the Klales et al.'s method, despite the values from casework probably reflecting practitioners using information beyond the method reported to make a final sex estimate.