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The research that Yale University professor and Analysis Group affiliate Judith Chevalier and several coauthors have done exploring the manipulation of online ratings systems was featured in a recent Slate.com article, “Should You Trust Online Reviews?” (Aug. 14, 2012)

The author, Ray Fisman, suggests that, in theory, buyers’ access to crowdsourced reviews of various goods and services should give them the information they need to make sound purchasing decisions and should insulate them from unscrupulous business practices by sellers. “Yet recent studies suggest that online reviewing is hardly a perfect consumer defense system,” he writes, noting a recent empirical investigation of promotional reviews conducted by Dr. Chevalier and her coauthors, Dina Mayzlin of U.S.C.’s Marshall School of Business and Yaniv Dover of Dartmouth College’s Tuck School of Business.

The researchers examined the extent to which “fakery” occurs with regard to these reviews and the market conditions that encourage or discourage people to post ratings. Specifically, they looked at reviews of hotels posted on Expedia.com and TripAdvisor.com, factoring in the differences in posting protocols for each site and in the ownership structures of the hotels that were reviewed online – that is, whether the hotels were independent sites owned by single-unit owners or branded chains owned by multiunit owners.

Dr. Chevalier and her coauthors found that the net gains from promotional fake reviews are likely to be highest for the independent hotels and lowest for chain hotels; and that “hotels with a high-incentive to fake have a greater share of five-star (positive) reviews on TripAdvisor relative to Expedia.” Meanwhile, hotels that are in the vicinity of those with a high-incentive to fake have more one- and two-star (negative) reviews on TripAdvisor relative to Expedia, the researchers say, suggesting that some hotel proprietors may be targeting fake negative reviews at competing hotels.

The researchers’ findings also appear in Harvard Business Review's "Idea Watch" section (September 2012).

Read the working paper "Promotional Reviews: An Empirical Investigation of Online Review Manipulation"

Read the Slate.com article

Read the Harvard Business Review article (subscription required)