This paper takes a first step toward understanding the working of the online market for reviews. Most online review firms rely on unpaid volunteers to write reviews. Can a for-profit online review firm attract productive volunteer reviewers, limit the number of ranting or raving reviewers, and marginalize fake reviewers? This paper sheds light on this issue by studying reviewer productivity and restaurant ratings at Yelp, where reviewers are encouraged to establish a social image, and two competing websites, where reviewers are completely anonymous. Using a dataset of nearly half a million reviewer accounts, we find that the number (proportion) of prolific reviewers on Yelp is an order of magnitude larger than that on either competing site, more productive reviewers on all three websites are less likely to give an extreme rating, and restaurant ratings on Yelp tend to be much less extreme than those on either competing site.
©2011 Walter de Gruyter GmbH & Co. KG, Berlin/Boston