  Our paper contributes to the literature recommending approaches to make
online reviews more credible and representative. We analyze data from four
diverse major online retailers and find that verified customers who are
prompted (by an email) to write a review, submit, on average, up to 0.5 star
higher ratings than self-motivated web reviewers. Moreover, these
email-prompted reviews remain stable over time, whereas web reviews exhibit a
downward trend. This finding provides support for the existence of social
influence and selection biases during the submission of a web review, when
social signals are being displayed. In contrast, no information about the
current state of the reviews is displayed in the email promptings. Moreover, we
find that when a retailer decides to start sending email promptings, the
existing population of web reviewers is unaffected both in their volume as well
as the characteristics of their submitted reviews. We explore how our combined
findings can suggest ways to mitigate various biases that govern online review
submissions and help practitioners provide more credible, representative and
higher ratings to their customers.
