Older Adults’ Comprehension of Probabilistic Risk Expressions in a Vaccine Information Statement

Abstract

The probability of a risk can be expressed in various formats such as percentages, frequencies, or words. People must be able to understand these probabilistic risk expressions to make informed decisions about their health. However, research has shown that people, especially older adults, have difficulty comprehending probabilities (e.g., Gigerenzer, Gaissmaier, Kurz-Milcke, Schwartz, & Woloshin, 2007; Kutner, Greenberg, & Baer, 2005; Lipkus, Samsa, & Rimer, 2001). In this study, the relationship between the probability risk format (frequency, percentage, or words) and how older adults described and understood the probabilistic information was examined using a teach-back approach and a recall test. Four females and one male participated; mean age was 73.2 years (SD=5.2). The results suggest that people do attend to probabilistic risk information and that presenting risk probabilities using words or percentages supports comprehension.