The unintended effects of health information base rates on health risk estimates and behavioral intentions

Abstract

Social marketers and health advertisers often use statistical health information to craft customized messages for specific consumer segments. However, the composition of these segments can vary greatly, inherently resulting in different base rate percentages about the same health issue (e.g. ‘51.9% of all COVID 19-related deaths in the U.S. occurred among Caucasians’ vs. ‘16.6% of all COVID 19-related deaths in the U.S. occurred among Hispanics’) that can potentially lead to different responses from consumers. Therefore, this research examines how individuals process, and respond to, manipulated base rates. Study 1 demonstrates that higher (vs. lower) base rates increase individuals’ healthy behavioural intentions by elevating their risk perceptions. Study 2 uncovers a more complex serial process underlying the impact of base rates on intentions to follow recommended behaviours in health messages. Importantly, we demonstrate a critical effect reversal such that higher base rates have an unintended negative impact on individuals’ compliance intentions when involvement is lower (vs. higher). Overall, our findings show how the use of base rates in health messages can serve as a ‘double-edged sword’.

Keywords:

• Consumer health
• social marketing
• health framing
• health risk
• compliance
• self-positivity bias
• information base rates
• involvement
• obesity
• boomerang effect
• vaccines
• COVID-19

Disclosure statement

No potential conflict of interest was reported by the authors.

Notes on contributors

Dr. Christopher Newman is P.M.B Self Chair of Free Enterprise and Associate Professor of Marketing at the University of Mississippi.

Dr. Saim Kashmiri is Mr. and Mrs. James E. King Professor and Associate Professor of Marketing at the University of Mississippi.

Notes

1 As discussed in greater detail later, information base rates are calculated by dividing the incident level of a certain event (e.g., number of people who have lung cancer) by the size of a chosen referent group (e.g., Asian Americans) and are often reported as percentages (e.g., “20% of all women over 65 have high blood pressure”).

2 It should be acknowledged that accurate base rate manipulations in (health) communications are not illegal nor considered false advertising, though some can (and do) implicitly mislead consumers (see Hastak and Mazis 2011).

3 Involvement refers to “message involvement” throughout for the sake of clarity and consistency.

Additional information

Funding

The authors greatly appreciate the financial support for this research from the P.M.B. Self & William King Self fund, as well as the Mr. and Mrs. James E. King fund.