Although “evidence” is often used as an important argument in persuasive health campaigns, it remains unclear what type of evidence has the strongest impact on particular outcome variables. We conducted a meta-analysis in which the effects of statistical and narrative evidence on beliefs, attitude, and intention were separately compared. Statistical evidence was found to have a stronger influence than narrative evidence on beliefs and attitude, whereas narrative evidence had a stronger influence on intention. We explain these findings in terms of the match between the specific characteristics of the two types of evidence and those of the outcome variables. Statistical evidence, beliefs, and attitude all relate primarily to cognitive responses, whereas both narrative evidence and intention relate more specifically to affective responses. We conclude that communication professionals developing health campaigns should match the type of evidence to the main communication objectives.
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