Are professionals better at assessing the evidential strength of different types of forensic conclusions compared to students?

Last Updated on April 5, 2024 by Ranking

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.

Both students and professionals in the field of crime investigation and law tend to overestimate the strength of categorical conclusions and underestimate the strength of weak categorical conclusions, with legal professionals performing better than crime investigators and legal students performing worse than crime investigation students.

A group led by Elmarije van Straalen from the Politieacademie (2023) studied the interpretation of forensic conclusions by professionals and students. The study examines how criminal justice professionals and students interpret forensic reports and their conclusions. Both groups had difficulty understanding the reports and made mistakes, but professionals were generally better at assessing the conclusions. The study aims to determine if education and experience influence the ability to assess forensic conclusions correctly. The reports consisted of a one-page summary of a fingerprint examination. Both students and professionals had a similar understanding of the conclusions, but professionals assessed the strength of weak conclusions higher than students.

There were 96 students included in the analysis.

The conclusions appear to substantiate prior work in this field: “Participants in a study had doubts about their ability to assess the strength of a conclusion when it was not clearly strong or weak. This aligns with previous research that found participants were better at recognizing the strength of more extreme values,” van Straalen argued.

The investigators concede that “This study examined the impact of experience and education on the interpretation of forensic conclusions using fingerprint evidence reports. The study found that the difference in sample size between student and professional participants did not affect the results. The study also acknowledged limitations, such as the use of an online questionnaire and the lack of additional information provided to participants. The authors of the study made various contributions to the research.”

The researchers advocate that further research is needed to determine the most effective forms of feedback, such as reviews, in the forensic field.

van Straalen, E. K., de Poot, C. J., Malsch, M., & Elffers, H. (2023). The interpretation of forensic conclusions by professionals and students: Does experience matter? Forensic Science International: Synergy, 7, 100437. doi.org/10.1016/j.fsisyn.2023.100437