Keynote: Dina Mayzlin

Extremity Bias in Online Reviews: A Field Experiment

Dina Mayzlin, University of Southern California

In a range of studies across many platforms, submitted online ratings have been shown to be characterized by a distribution with disproportionately-heavy tails. These have been referred to as “u-shaped distributions” or “j-shaped distributions.”
Our focus in this paper is on understanding the underlying process that yields such a distribution. We develop a simple analytical model to capture the most-common explanation: differences in utility associated with posting extreme vs moderate reviews. We compare the predictions of this model with those of an alternative theory based on customers forgetting about writing a review over time.
The forgetting rate, by assumption, is higher for moderate reviews. The two models yield stark differences in the predicted dynamics of extremity bias. 
To test our predictions, we use data from a large-scale field experiment with an online travel platform. In this experiment, we varied the time at which the firm sent out a review solicitation email. Specifically, the time of review solicitation ranged between one and nine days after the end of one’s vacation. This manipulation allows us to observe the extremity dynamics over an extended period both before and after the firm’s solicitation email.
Dina Mayzlin is an Associate Professor of Marketing at the Marshall School of Business at University of Southern California.  Her research focuses on how businesses manage social interactions. She also studies advertising and communication strategies. Professor Mayzlin's research has won a number of awards, including the John D.C. Little Best Paper Award, the ISMS Long Term Impact Award, the O'Dell Long Term Impact Award, and the Frank M. Bass Outstanding Dissertation Award. She serves on the editorial boards of Marketing Science and International Journal of Research in Marketing. Prior joining USC, Professor Mayzlin served on the faculty of Yale University's School of Management.  She received her PhD from MIT.