Representing randomness in the communication of individualized cancer risk estimates: effects on cancer risk perceptions, worry, and subjective uncertainty about risk.

OBJECTIVE: To test the effect of novel representations of randomness on risk perceptions, worry, and subjective uncertainty about individualized colorectal cancer risk estimates.
METHODS: A web-based factorial experiment was conducted, in which 225 adults aged 40 years and older were provided with hypothetical individualized colorectal cancer risk estimates, using 5 different textual and visual representations varying in expressed randomness. Outcome measures were perceived cancer risk, cancer worry, and subjective uncertainty about cancer risk; the moderating effect of dispositional optimism was also examined.
RESULTS: Representational format was significantly associated with subjective uncertainty about cancer risk, but not with perceived cancer risk or worry. A format using software-based animation to express randomness dynamically led to the highest subjective uncertainty, although a static visual non-random format also increased uncertainty. Dispositional optimism moderated this effect; between-format differences in uncertainty were significant only for participants with low optimism.
CONCLUSION: Representing randomness in individualized estimates of cancer risk increases subjective uncertainty about risk. A novel dynamic visual format produces the greatest effect, which is moderated by individual differences in optimism. PRACTICE IMPLICATIONS: Novel representations of randomness may be effective in improving people's understanding of the essential uncertainty pertaining to individualized cancer risk estimates.