Whether it’s booking a hotel or shopping online: Many people base their decisions on customer reviews. At the same time, publicly posted reviews provide a strong incentive for companies to improve products and services. For this to work, customer feedback has to be both honest and informative. <link ims team prof-dr-ben-greiner>WU Professor Ben Greiner uses field data analysis of online marketplaces like eBay and laboratory tests to investigate which online feedback systems work best. He observed a number of different patterns of social behavior that were affected by the feedback rules of each system.

Revenge feedback for negative reviews

On eBay, one of the market platforms that allows buyers and seller to provide mutual feedback, Greiner’s study provides evidence for strong reciprocity in feedback behavior. Positive reviews from buyers were almost always rewarded with positive feedback from vendors, whereas a negative review almost always resulted in negative revenge feedback from the seller. As a result, many people who had a negative experience with a purchase chose not to leave feedback at all, for fear of getting negative feedback in return. This distorts the entire feedback image: 98% of the feedback given on eBay is positive. “This means that the collective feedback offers only a limited amount of information,” says Greiner, “Our laboratory studies have shown that this is the result of the system’s openness. If you change the rules and don’t publish feedback until both parties to the transaction have submitted their review, it leads to more negative, honest feedback but, unfortunately, also to a lower rate of participation in the feedback system as a whole. It also works better if only one-sided feedback is allowed.”

Poor compromise

Allowing posters the option to retract feedback may also have unintended effects. Ideally, this option allows both parties to the transaction to find a solution in the event of a conflict. The studies revealed the opposite behavior, however: For example, sellers who were expecting negative reviews posted negative feedback about buyers as leverage to later convince the buyers to retract their own negative review. “This also results in feedback distortion. The information value and effectiveness of the feedback system are considerably reduced,” says Greiner. Overall it was shown that the specific rules of individual feedback systems determine the strategic incentives buyers and sellers are exposed to when they contribute their feedback. An efficiently designed and planned feedback system takes these factors into account.

The study

For his research, Ben Greiner used field data from eBay and other online market platforms as well as data from laboratory experiments. Greiner explains, “In the field, there are a number of variables we can’t observe. For this reason, we recreate markets in the computer laboratory and ask human participants to make decisions taking the roles of buyers and sellers. The profits that participants made in the lab experiments were paid out to them in cash. This ensures the authenticity of the decisions made. Like in a wind tunnel, we can then change the design, i.e. the rules of the feedback system, and observe the reactions of the buyers and sellers.”

Ben Greiner

Ben Greiner has been head of WU’s Institute for Markets & Strategy and the Competence Center for Experimental Research, including the WULabs, since 2016. Originally from Germany, he studied business administration at Humboldt-Universität zu Berlin, earned his doctorate at the University of Cologne, and then spent two years as a researcher at Harvard University. Before coming to WU, Greiner taught at the University of New South Wales in Sydney, Australia. Ben Greiner’s research focuses on fundamental questions of economic interaction in social contexts. This includes, for example, how groups generate joint decisions based on the opinions of the group members, or how uncertainty about the preferences and strategies of other acting agents affects our cooperative and market decisions. He also investigates more applied research questions like designing and improving real markets, institutions, and organizations. His research contributed to market platform eBay’s decision to reconfigure their worldwide feedback system and to the Australian government’s plans to develop a CO₂ emissions trading system. His work has been published in top journals like the American Economic Review, the Economic Journal, the Journal of Public Economics, Management Science, and others.

Engineering Trust: Reciprocity in the Production of Reputation Information.
Management Science 2013, https://doi.org/10.1287/mnsc.1120.1609

Dispute Resolution or Escalation? The Strategic Gaming of Feedback Withdrawal Options in Online Markets. Management Science 2018, https://doi.org/10.1287/mnsc.2017.2802

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