Exploring mock juror evaluations of forensic evidence conclusion formats within a complete expert report

Abstract

Many researchers have examined lay evaluations of forensic expert evidence using brief statements but few have examined evaluations of these statements when presented within the context of complete expert reports. We present data from two experiments which examined mock juror evaluations of different conclusion formats within a complete expert report. Participants read case information and a shoeprint expert report which varied by conclusion format (likelihood ratio, random-match probability, verbal label, or categorical statement). Participants then answered questions about evidence weight and verdict, and completed measures of individual differences. In both experiments, conclusion format did not significantly impact lay evaluations of the expert report. These findings challenge the perception that using scientifically robust statistical formats in expert reports hinders lay understanding compared to simpler, but problematic, categorical formats. They also underscore the importance of other features of expert reports in shaping how laypeople evaluate forensic expert evidence.