COMMUNICATING LOW-RISK MAGNITUDES - INCIDENCE RATES EXPRESSED AS FREQUENCY VERSUS RATES EXPRESSED AS PROBABILITY

The study investigated the effects of incidence rates stated as a prob ability (e.g., .0006) and incidence rate information expressed in term s of frequency (e.g., 600 in 1,000,000) on risk-avoidant behavior. Sub jects were informed about the risks associated with an old and a new, improved medication. They were asked how much they were willing to pay for the safer medicine. Risk information was given either in a freque ncy or a probability format. The second factor manipulated was the lev el of risk, either high or low. As expected, analysis of variance yiel ded a significant interaction. Subjects confronted with high risk in t he frequency format were willing to pay the highest prices for the imp roved medication. The choice between frequency or probability format c an be made according to the goal of the communication of risk.