Verbal versus numerical probabilities: Does format presentation of probabilistic information regarding breast cancer screening affect women’s comprehension?

Abstract

Objective: To test whether the format in which women receive probabilistic information about breast cancer and mammography affects their comprehension. Methods: A convenience sample of 180 women received pre-assembled randomized packages containing a breast health information brochure, with probabilities presented in either verbal or numeric format, and four questionnaires. Enclosed questionnaires assessed women’s knowledge of breast health, socio-demographic/ clinical characteristics, comprehension of breast health information brochure and format preference. Results: Nearly two-thirds of the study participants reported a preference for the numeric format. However, the study results showed that comprehension was significantly higher among women who received probabilistic information in verbal format than those who received the information in numeric format. This higher degree of comprehension was sustained even if the verbal format was inconsistent with the respondents’ format preference, and even if the respondents’ educational background were relatively limited. Women’s comprehension was strongly associated with the interaction between received format and their format preferences as well as their education level and their perceived benefit of early detection of breast cancer. Conclusion: The study demonstrates that comprehension of information depends on: (1) women’s readiness to receive information; and (2) their education and numeracy skills in processing and interpreting probabilistic information, particularly, when presented in quantitative format. Attention must be paid to these factors when designing or communicating breast health information in order to ensure full comprehension of information, and to avoid any potential discrimination which people may face relating to their poor education or numeracy skills. Systematic investigation into the relationships among readiness, numeracy problems, and format preferences could help build effective guidelines for providing women with appropriate and comprehensible information.