Does explaining the meaning of likelihood ratios improve lay understanding?

Area of Science:

• Cognitive Psychology
• Legal Decision-Making
• Statistical Reasoning

Background:

• Previous research on layperson understanding of likelihood ratios (LRs) often lacked explicit explanations.
• Most studies used written formats, unlike typical courtroom oral testimony.

Purpose of the Study:

• To investigate the effect of expert witness explanations of LRs on layperson understanding.
• To assess if video testimony and explanations reduce the prosecutor's fallacy.

Main Methods:

• Participants viewed video testimony, with some receiving an explanation of LRs from an expert witness.
• Effective LRs (posterior odds/prior odds) were compared to presented LRs.
• The incidence of the prosecutor's fallacy was analyzed.

Main Results:

• A small increase in accurate LR understanding was observed when explanations were provided.
• The explanation did not significantly decrease the occurrence of the prosecutor's fallacy.
• Overall, results did not provide convincing evidence of improved LR comprehension.

Conclusions:

• While explanations may offer marginal benefits, they are not sufficient to ensure accurate understanding of likelihood ratios.
• Factors beyond the explanation's clarity may influence comprehension and fallacy occurrence.
• Further investigation into effective pedagogical strategies for LRs is warranted.