Using Time Intervals Between Expected Events to Communicate Risk Magnitudes

Abstract

Because members of the public have difficulty understanding risk presented in terms of odds ratios (e.g. 1 in 1000) and in comparing odds ratios from different hazards, we examined the use of time intervals between expected harmful events to communicate risk. Perceptions of the risk from a hypothetical instance of naturally-occurring, cancer-causing arsenic in drinking water supplies was examined with a sample of 705 homeowners. The risk was described as either 1 in 1000 or 1 in 100,000 and as present in a town of 2000 people or a city of 200,000 people. With these parameters, the time intervals ranged from 1 expected death in 3500 years (1 in 100,000 risk, small town) to 1 death every 4 months (1 in 1000 risk, city). The addition of time intervals to the odds ratios significantly decreased perceived threat and perceived need for action in the small town but did not affect response for the city. These framing effects were nearly as large as a 100-fold difference in actual risk. Instances when this communication approach may be useful are discussed.

Lay views on uncertainty in environmental health risk assessment

“…Testing the impact of presenting su ch data (and their u ncertainties) in other terms -whether qu antitative, su ch as time intervals between expected events (Weinstein et al, 1996), or qu alitative (Frewer et al, 1998) -wou ld be helpfu l.…”

Perils, Pitfalls, and Possibilities in Talking About Medical Risk

“…The way a discussion is framed may help determine the decision a person reaches, [8][9][10][11] and features such as the physician's tone of voice or body language or the choice of what information to present first may influence the patient's perception of risk. Even the language chosen may contain loaded terms that can jeopardize unbiased communication.…”

Assessing and modelling catastrophic risk perceptions and attitudes in agriculture: a review

“…So if the degree of conviction of the subjective probability is not very high, the subjective probability and the choice based on it may change because of additional data (Hagihara, 2002). As explained in the following, Weinstein et a!. (1996) and Kunreuther et a!.…”

“…Senkondo (zooz). Weinstein et al (1996); Kunreuther et al (Z001). Smidts (1990); Pennings (1998); Senkondo (zooo); Ganderton et al (zooo); Van Asseldonk et al (zooz).…”