PAPER GENERAL Angi M. Christensen, 1 Ph.D.; Christian M. Crowder, 2 Ph.D.; Stephen D. Ousley, 3 Ph.D.; and Max M. Houck, 4 Ph.D. Error and its Meaning in Forensic Science* ABSTRACT: The discussion of “error” has gained momentum in forensic science in the wake of the Daubert guidelines and has intensified with the National Academy of Sciences’ Report. Error has many different meanings, and too often, forensic practitioners themselves as well as the courts misunderstand scientific error and statistical error rates, often confusing them with practitioner error (or mistakes). Here, we present an overview of these concepts as they pertain to forensic science applications, discussing the difference between practitioner error (including mistakes), instrument error, statistical error, and method error. We urge forensic practitioners to ensure that potential sources of error and method limitations are understood and clearly communicated and advocate that the legal community be informed regarding the differences between interobserver errors, uncertainty, variation, and mistakes. KEYWORDS: forensic science, error, limitation, forensic anthropology, Daubert, mistake Discussion regarding “error” in forensic science analyses gained momentum following the Daubert ruling (1) and has intensified with the National Academy of Sciences’ National Research Council Report Strengthening Forensic Science in the United States: A Path Forward (2). The role of science within the judicial system is nothing novel; however, the focus has shifted to include the evaluation of methods and techniques rather than simply the expert’s interpretation of the results. Establishing scientific validity is challenging within the forensic sciences considering that the concept of error has different mean- ings and functions in the courtroom compared with the research setting (3). Estimating method validity and understanding error are important, however, regardless of whether conclusions end up in court. The concept of error has been problematic, and too often, the courts as well as forensic practitioners misunderstand the mean- ing of error as it relates to forensic science research, procedures, and techniques. Error can be defined in a number of ways including the following: an act, assertion, or belief that uninten- tionally deviates from what is correct, right, or true; the condi- tion of having incorrect or false knowledge; the act or an instance of deviating from an accepted code of behavior; or a mistake. Mathematically and statistically, error may refer to the difference between a computed or measured value and a true or theoretically correct value. Considering these definitions, it is apparent that error in the forensic science realm can result from a number of different causes, contributing to the complexity in understanding the potential source(s) of error. The convergence of science and law has made the identification and interpretation of error in the courtroom an even greater challenge, especially as officers of the court typically lack a scientific background and specific knowl- edge regarding error analysis. Thus, the concept of error is often vague and subject to a variety of interpretations. Admissibility criteria for expert testimony in the United States were redefined in the 1993 Supreme Court Daubert decision (1) resulting in significant changes in and interpretation of the Federal Rules of Evidence Rule 702 (4). The Daubert criteria were intended to provide guidelines for admitting scientific expert testimony to ensure its reliability and validity. In federal cases and in states that have adopted the Daubert criteria, trial judges might consider the following factors to assess the admis- sibility of scientific or technical expert testimony: (i) whether the theory or technique in question can be (and has been) scientifi- cally tested, (ii) whether it has been subjected to peer review and publication, (iii) its known or potential error rate, (iv) the existence and maintenance of standards controlling its operation, and (v) whether it has attracted widespread acceptance within a relevant scientific community (1:593-94). While the tumult surrounding the potential impact of the Daubert ruling on the forensic sciences seemingly began to dis- sipate over the years, the challenge to the forensic science com- munity was renewed with the release of the National Academy of Sciences’ National Research Council Report Strengthening Forensic Science in the United States: A Path Forward (2). This document outlined the scientific and technical challenges that must be met in order for the forensic science enterprise in the United States to operate at its full potential. In the Council’s opinion, some disciplines were found to lack scientific rigor, leading 1 George Mason University, Fairfax, VA. 2 Office of Chief Medical Examiner, New York City, NY. 3 Mercyhurst University, Erie, PA. 4 Department of Forensic Sciences, Consolidated Forensic Laboratory, Washington, DC. *Presented at the 63rd Annual Meeting of the American Academy of Forensic Sciences, February 20–26, 2011, in Chicago, IL. The research pre- sented in this manuscript was not conducted under the auspices of the New York City Office of Chief Medical Examiner (NYC-OCME) or the Depart- ment of Forensic Sciences (DFS). The opinions expressed herein are those of the authors and do not reflect the opinions of the NYC-OCME or the DFS. Received 2 June 2012; and in revised form 26 Sept. 2012; accepted 27 Oct. 2012. © 2013 American Academy of Forensic Sciences 123 J Forensic Sci, January 2014, Vol. 59, No. 1 doi: 10.1111/1556-4029.12275 Available online at: onlinelibrary.wiley.com