Inter- and Intra-observer Error in Forensic Anthropology: Based upon Langley et al. 2016 Data Collection Procedures for Forensic Skeletal Material 2.0 for the Cranium and Femur

Authors

Maggie M. Klemm, University of Nebraska-LincolnFollow
Dakota L. Taylor, University of Nebraska-LincolnFollow

Date of this Version

2024

Document Type

Article

Citation

Nebraska Anthropologist (2024) 30

Comments

Copyright 2024, Maggie M. Klemm and Dakota L. Taylor. Used by permision

Abstract

Following the Daubert v. Merrell Dow Pharmaceuticals (1993) ruling three decades ago, guidelines were established for determining the reliability and validity of expert testimony in court. These guidelines include considerations of whether the theory and methodologies employed have been tested, the establishment of potential or known error rates, and the existence and maintenance of the standards (Christensen, 2004). Testifying in court as an expert witness has become a critical role as a forensic anthropologist. As such, the methodologies, techniques, and standards utilized by forensic anthropologists must be carefully considered and adhere to the Daubert guidelines within the court system. One of the established standard manuals is the Data Collection Procedures for Forensic Skeletal Material 2.0 (Langley et al. 2016). This manual provides the most up-to-date data collection procedures and instructions for taking osteometric measurements of skeletal landmarks, providing the basis for estimates of biological sex, population affinity, and stature of unknown human remains. Within forensic anthropology, the use of osteometric data is frequent, yet little research has explored both interobserver and intraobserver variability for various measurements, as well as testing the reliability and accuracy of different measurement devices.

In this study, two observers took repeated measurements of the femora and crania of two skeletal casts. The observers adhered to the instructions provided in the Data Collection Procedures for Forensic Skeletal Material 2.0 (Langley et al. 2016) when taking these measurements. The aim of this study is to quantify the intra- and interobserver variability expressed in these measurements and assess the thoroughness of the instructions and descriptions provided in the data collections manual. Overall, it was observed that the crania measurements reflected higher rates of inter- and intraobserver variability, whereas the femora measurements showed the least variability. Discrepancies were also observed between the units of measurements for certain tools (i.e., sliding and spreading calipers measure in centimeters while the osteometric board measures in millimeters). This data is important as it sparks conversation concerning the variability and accuracy of osteometric measurements in connection with the directions provided in the standard manual. This research will be expanded in the future to include more skeletal casts and observers to quantify the inter- and intraobserver error rates and inter-device reliability with a larger sample dataset.

Cited: N.R. Langley, L.M. Jantz, S.D. Ousley, R.L. Jantz, G.S. Milner. (2016). Data Collection Procedures for Forensic Skeletal Material 2.0. University of Tennessee, Knoxville.