Does Advertising Bias Product Reviews? An Analysis of Wine Ratings
31 Pages Posted: 30 Sep 2009
Date Written: September 29, 2009
In markets for experience goods, publications exist to help consumers decide which products to purchase. However, in most cases these publications accept advertising from the very firms whose products they review, raising the possibility that they bias product reviews to favor advertisers. To test for biased product reviews, I exploit the fact that of the two major U.S. wine publications only Wine Spectator accepts advertising. Using ratings from Wine Advocate to proxy for quality, I find that advertisers earn slightly higher ratings in Wine Spectator. However, I find only weak evidence that the selective retasting of advertisers' wines contributes to the higher ratings. Moreover, conditional on published ratings, Wine Spectator is no more likely to bestow awards upon advertisers. I conclude that while advertising may influence ratings on the margin, Wine Spectator appears largely to insulate reviewers from the influence of advertisers.
Keywords: biased product reviews, media bias, advertising, reputation, wine
JEL Classification: L15, M37
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