Two arch criteria of the ilium for sex determination of immature skeletal remains: A test of their accuracy and an assessment of intra- and inter-observer error Hugo F.V. Cardoso a,b,c, * , Shelley R. Saunders c a Departamento de Antropologia, Universidade de Coimbra, Rua do Arco da Traic ¸a ˜o, 3000-056 Coimbra, Portugal b Faculdade de Medicina, Universidade do Porto, Al. Prof. Herna ˆni Monteiro, 4200-319 Porto, Portugal c Department of Anthropology, McMaster University, Chester New Hall 524, 1280 Main Street West, Hamilton, Ontario, Canada L8S 4L9 Received 1 November 2007; received in revised form 22 January 2008; accepted 29 January 2008 Available online 17 March 2008 Abstract Although the assignment of sex to immature skeletal remains is considered problematic, some traits have been considered useful for both forensic and bioarchaeological applications. One such trait is the arch criterion found in subadult ilia, which is defined relative to the greater sciatic notch-auricular surface area. In adults, the composite arch has also been described in relation to this area and has proven relatively successful in sex determination. This study offers an examination of the accuracy of the arch criterion and the composite arch in determining the sex of subadult skeletal remains, and an assessment of intra- and inter-observer scoring error. A sample of 97 skeletons of known sex and age (<15 years) from the Lisbon collection (Portugal) were selected and the traits were scored by three observers on orthogonal photos of each ilium. In general the agreement within (67.7–88.5%) and between (50.5–76.3%) examiners was poor and overall accuracy (26.7–52.6%) did not meet the expectations of that reported in previous studies. The authors suggest that this derives from great variation in morphology, difficulties in interpreting criteria and possibly a lack of association between the expression of the traits and sex. Careful examination of sex-related morphology in the immature skeleton and additional blind tests of so-called useful traits should continue to be carried out. # 2008 Elsevier Ireland Ltd. All rights reserved. Keywords: Forensic science; Subadults; Sex determination; Ilium; Arch criterion; Composite arch 1. Introduction There has been widespread recognition of the inability to determine sex in immature skeletal remains [1]. Several attempts to develop methods to determine the sex of subadult skeletons have relied on the identification of adult sex-related features. This relates to the expectation that adult-like differences begin to show even in infancy. Since the pelvis is the most sexually dimorphic part of the adult skeleton it would make sense to look for dimorphism in the subadult pelvis and there is a long literature on this subject [2–8]. One area of the skeleton that has received considerable investiga- tion is the greater sciatic notch-auricular surface area in the pelvis. In adults, the composite arch is defined in relation to this area and has been successfully utilized in sex determination. The composite arch was proposed by Genove ´s [9], who obtained 80% of correct allocation accuracy for males and 88% for females in a mixed sample of English origin. Similar correct sex allocation accuracies were obtained by Bruzek [10], 67% for males and 92% for females in a French sample (N = 162), and 78% for males and 87% for females in a Portuguese sample (N = 240). In the subadult skeleton, the arch criterion is also defined in relation to the greater sciatic notch-auricular surface area and has also been relatively successful in sex determination. The arch criterion was proposed by Schutkowski [11] and is very similar to the composite arch criterion. A correct sex allocation accuracy of 81.5% for males and 60% for females was obtained by Schutkowski [11] in a sample of 61 subadult skeletons from birth to 5 years of age, using the Spitalfields collection in www.elsevier.com/locate/forsciint Available online at www.sciencedirect.com Forensic Science International 178 (2008) 24–29 * Corresponding author at: Departamento de Antropologia, Universidade de Coimbra, Rua do Arco da Traic ¸a ˜o, 3000-056 Coimbra, Portugal. Tel.: +351 239 829 051; fax: +351 239 823 491. E-mail address: hcardoso@antrop.uc.pt (H.F.V. Cardoso). 0379-0738/$ – see front matter # 2008 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.forsciint.2008.01.012