In health and risk communication, evidence is a message feature that can add credibility, realism, and legitimacy to health and risk messages. Evidence is usually defined into two types: statistical or narrative. Statistical evidence employs quantifications of events, places, phenomena, or other facts, while narrative evidence involves stories, anecdotes, cases, or testimonials. While many health and risk messages employ statistical or factual information, narrative evidence holds appeal for health and risk communication for its utility in helping individuals learn their risks and illnesses through stories and personal experiences. In particular, narratives employed as evidence in a health or risk message especially hold value for their ability to communicate experiences and share knowledge, attitudes, beliefs, and ideas about complex health issues, propose behavior change, and assist individuals coping with disease. As a result, the personal experiences shared, whether they are from first-hand knowledge, or recounting another’s experience, can focus attention, enhance comprehension for risks, and recall of health and risk information. Furthermore, readers engage with the story and develop their own emotional responses which may align with the purpose of the health and risk message. Narratives, or stories, can occur in many ways or through various points of view, but the stories that “ring true” to readers often have a sense of temporality, coherence, and fidelity. As a result, formative research and pre-testing of health and risk messages with narratives becomes important to understand individual perceptions related to the health issue and the characters (or points of view). Constructs of perceived similarity, interest, identification, transportation, and engagement are helpful to assess in order to maximize the usefulness and persuasiveness of narratives as evidence within a health and risk message. Additionally, understanding the emotional responses to narratives can also contribute to perceptions of imagery and vividness that can make the narrative appealing to readers. Examining what is a narrative as evidence in health and risk messages, how they are conceptualized and operationalized and used in health and risk messages is needed to understand their effectiveness.
Julie E. Volkman
Persuasive messages use statistical evidence in order to convince an audience to accept a conclusion. Statistical evidence represents a compilation of experiences structured and collected in a manner that permits expression in mathematical form. Research demonstrates that the use of statistical evidence increases the persuasiveness of a message, and a message that uses both statistical and narrative evidence generates the greatest persuasiveness. Statistical evidence can take the form of summarizing the collective opinion of experts on a topic or an expression of the collective set of experiences. The challenge becomes gaining acceptance of statistical expressions of experience versus what is perceived as the narrative or lived experience of the single person. Statistical evidence is often presented using a mathematical expression to indicate the size or force of the evidence. The accumulation of statistical evidence often involves the use of meta-analysis to reduce Type I (false positive) and Type II (false negative) error. The use of evidence is strategic and can target specific elements of belief by understanding the structure of beliefs and the connectivity among elements. The use of the Subjective Probability Model provides a means to capitalize on the use of evidence by changing probabilities in beliefs to increase the effectiveness of a message campaign. Statistical evidence, however, may be ineffective under circumstances referred to as the “base-rate fallacy.” The base-rate fallacy occurs when the presentation of statistical information is accepted, but examples are used that contradict the base-rate. The impact of the use of the example is to create a shift in the belief in the typicality of the example, despite knowledge of the base-rate. Fear appeals provide a particularly useful and important application of statistical evidence in the pursuit of public health campaigns. The tenets of the Extended Parallel Processing Model indicate that message effectiveness relies on a combination of: (a) perceived severity of the threat, (b) perceived vulnerability to the threat, (c) perceived efficacy of the solution, and (d) perceived personal efficacy of the solution. Each element is largely impacted by the application and use of statistical information to make claims. The use of statistics generally outlines the argument and supports the conclusion offered in support of a conclusion offered to the message recipient. Statistical evidence when used in a message often offers data or information that becomes the justification for a conclusion. A large part of a message becomes gaining acceptance of information by an audience, then explaining (reasoning) to the audience how those facts support a conclusion, often involving some type of recommendation for behavior. Understanding statistical evidence requires understanding how the material functions within the context of the belief system of the individual.