A comparison of the persuasive effectiveness of qualitative versus quantitative evidence: A test of explanatory hypotheses

This investigation examined the effectiveness of quantitative (statistical) and qualitative (narrative) types of evidence in impacting initial attitude change and the persistence of that change. Vividness, expertise, trustworthiness, and retention were examined as potential mediating variables. Furthermore, this research tested a number of competing hypotheses such as the vividness hypothesis, the availability hypothesis, and the under‐utilization hypothesis. The findings indicate that both types of evidence were equally effective in changing attitudes. However, the attitude change elicited by qualitative evidence tended to be significantly more persistent over time. These data were inconsistent with the vividness and the under‐utilization hypotheses. In contrast, these data were consistent with the availability hypothesis. Recall was higher for those subjects exposed to qualitative evidence. Additionally, retention was found to moderate the effect of evidence on attitudes.

Key concepts:

• Evidence
• persuasion
• case histories
• statistical evidence