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.