The interpretation of forensic conclusions by professionals and students: Does experience matter?

Elmarije K van Straalen; Christianne J de Poot; Marijke Malsch; Henk Elffers

doi:10.1016/j.fsisyn.2023.100437

The interpretation of forensic conclusions by professionals and students: Does experience matter?

Forensic Sci Int Synerg. 2023 Sep 29:7:100437. doi: 10.1016/j.fsisyn.2023.100437. eCollection 2023.

Authors

Elmarije K van Straalen^{1

2}, Christianne J de Poot^{1

2

3}, Marijke Malsch^{4

5}, Henk Elffers⁴

Affiliations

¹ Amsterdam University of Applied Sciences, Forensic Sciences, P.O. Box 1025, 1000 BA Amsterdam, the Netherlands.
² VU University Amsterdam, Criminology Department, De Boelelaan 1105, 1081 HV Amsterdam, the Netherlands.
³ Police Academy of the Netherlands, Apeldoorn, the Netherlands.
⁴ Netherlands Institute for the Study of Crime and Law Enforcement NSCR, Amsterdam, the Netherlands.
⁵ Open University, Heerlen, the Netherlands.

Abstract

Are professionals better at assessing the evidential strength of different types of forensic conclusions compared to students? In an online questionnaire 96 crime investigation and law students, and 269 crime investigation and legal professionals assessed three fingerprint examination reports. All reports were similar, except for the conclusion part which was stated in a categorical (CAT), verbal likelihood ratio (VLR) or numerical likelihood ratio (NLR) conclusion with high or low evidential strength. The results showed no significant difference between the groups of students and professionals in their assessment of the conclusions. They all overestimated the strength of the strong CAT conclusion compared to the other conclusion types and underestimated the strength of the weak CAT conclusion. Their background (legal vs. crime investigation) did have a significant effect on their understanding. Whereas the legal professionals performed better compared to the crime investigators, the legal students performed worse compared to crime investigation students.

Keywords: Communicating uncertainty; Criminal justice professionals; Evidence interpretation; Forensic conclusions; Influence of experience.