Research Article Online Reviews of Credence Service Providers: What Do Consumers Evaluate, Do Other Consumers Believe the Reviews, and Are Interventions Needed? Shannon Lantzy, Rebecca W. Hamilton, Yu-Jen Chen, and Katherine Stewart Abstract Consumer-generated online reviews of credence service providers, such as doctors, have become common on platforms such as Yelp and RateMDs. Yet doctors have challenged the legitimacy of these platforms on the grounds that consumers do not have the expertise required to evaluate the quality of the medical care they receive. This challenge is supported by the economics of information literature, which has characterized doctors as a credence service, meaning that consumers cannot evaluate quality even after consumption. Are interventions needed to ensure that consumers are not misled by these reviews? Data from real online reviews shows that many of the claims made in real reviews of credence service providers focus on experience attributes, such as promptness, which consumers can typically evaluate, rather than credence attributes, such as knowledge. Follow-up experiments show that consumers are more likely to believe experience claims (vs. credence claims) made by other consumers, claims that are supported by data, and longer reviews even if they are not more informative. The authors discuss implications for consumers and credence service providers and possible policy interventions. Keywords argument quality, credence services, economics of information, online reviews, source effects Online supplement: https://doi.org/10.1177/0743915620950676 Consumer-generated online reviews of doctors have become common on platforms such as Yelp, Healthgrades, and RateMDs, and surveys show that consumers’ use of online reviews to choose doctors is increasing (Fox and Jones 2009). In 2018, 66.3% of consumers surveyed said online reviews were influential when choosing a new primary care physician (https://www.reviewtrackers.com/reports/online- reviews-survey/). Indeed, in a survey of 854 presurgical patients conducted at the Mayo Clinic, 81% (77%) said they would choose (not choose) a doctor based on solely on positive (negative) reviews (Burkle and Keegan 2015). However, doctors have strongly challenged the legitimacy of consumer reviews on the grounds that consumers do not have the expertise required to evaluate doctors (Andrews 2008; Jain 2010). Some doctors have even required their patients to sign documents promising never to review them (ElBoghdady 2012). A critical difference between credence service providers, such as doctors, mechanics, and computer specialists (Dulleck and Kerschbamer 2006), and experience service providers, such as hair stylists (Ostrom and Iacobucci 1995), car detailers, and landscapers, is that, by definition, consumers do not have the ability to evaluate the most impor- tant attributes of a credence service provider even after using the service (Darby and Karni 1973). For example, a patient may begin to feel better after treatment, but if she does not have medical training, she may never know whether her doctor cor- rectly diagnosed her symptoms or whether she would have felt equally good without treatment. Or, a patient may not feel better after treatment and blame the doctor, even though he Shannon Lantzy is Chief Scientist, Booz Allen Hamilton, USA (email: shannon. lantzy@gmail.com). Rebecca W. Hamilton (contact author) is Michael G. and Robin Psaros Chair of Business Administration and Professor of Marketing, McDonough School of Business, Georgetown University, USA (email: rebecca. hamilton@georgetown.edu). Yu-Jen Chen is Associate Professor of Marketing, Lingnan University, Hong Kong (email: yujenchen@ln.edu.hk). Katherine Stewart is former Associate Professor at the University of Maryland, USA (email: kstewart@rhsmith.umd.edu). Journal of Public Policy & Marketing 2021, Vol. 40(1) 27-44 ª American Marketing Association 2020 Article reuse guidelines: sagepub.com/journals-permissions DOI: 10.1177/0743915620950676 journals.sagepub.com/home/ppo