Probability Information in Risk Communication: A Review of the Research Literature

Abstract

Communicating probability information about risks to the public is more difficult than might be expected. Many studies have examined this subject, so that their resulting recommendations are scattered over various publications, diverse research fields, and are about different presentation formats. An integration of empirical findings in one review would be useful therefore to describe the evidence base for communication about probability information and to present the recommendations that can be made so far. We categorized the studies in the following presentation formats: frequencies, percentages, base rates and proportions, absolute and relative risk reduction, cumulative probabilities, verbal probability information, numerical versus verbal probability information, graphs, and risk ladders. We suggest several recommendations for these formats. Based on the results of our review, we show that the effects of presentation format depend not only on the type of format, but also on the context in which the format is used. We therefore argue that the presentation format has the strongest effect when the receiver processes probability information heuristically instead of systematically. We conclude that future research and risk communication practitioners should not only concentrate on the presentation format of the probability information but also on the situation in which this message is presented, as this may predict how people process the information and how this may influence their interpretation of the risk.

Development and Evaluation of an Online Risk Communication Teaching Program for Medical Students

“…The presentation then discussed the challenge of effective risk communication in terms of two major problems: (1) innumeracy and (2) cognitive biases and heuristics. It gave examples of these problems, drawing from relevant literature [7,8] and employing interactive exercises demonstrating common pitfalls in interpreting risk information. The presentation then discussed practical strategies for addressing the challenges of effective risk communication, summarized the essential steps of risk communication (Table 1), and reviewed essential steps in effective risk communication, operationalized using verbal Bscripts^-exemplary language to facilitate learning of communication skills (Table 2).…”

Framing Effects and Risk Perception: Testing Graphical Representations of Risk for the KIID

“…Price et al (2007) find supportive evidence for the use of graphical representations of frequency information. Instead of making general recommendations, Duklan & Martin (2002), Visschers et al (2009) and Spiegelhalter et al (2011) point out that the context in which the risk communication takes place plays an important role.…”

Decision aid for women considering breast cancer screening

“…Even interest and confidence in ability to use numerical information are not associated with actual comprehension or ability to use numbers (25). A recent review examined how numerical formats affect interpretation (24). When the probability of the test outcome is presented either in percentage (5 percent) or as single event probability (.05), the vast majority of experts and lay people strongly overestimate the value of the test.…”

“…Therefore, RRR should be presented together with ARR to give a more balanced view. The inverse of ARR, number needed to treat (NNT), could be an intuitively clear presentation of risk, but frequently people misinterpret it as well (24).…”

“…Visual representations of probability are more easily understood. Pictograms are a recommended and popular way to present risk information (24).…”