In a Race to Out-Rave, 5-Star Web Reviews Go for $5

In tens of millions of reviews on Web sites like Amazon.com, Citysearch, TripAdvisor and Yelp, new books are better than Tolstoy, restaurants are undiscovered gems and hotels surpass the Ritz.

Or so the reviewers say. As online retailers increasingly depend on reviews as a sales tool, an industry of fibbers and promoters has sprung up to buy and sell raves for a pittance.“For $5, I will submit two great reviews for your business,” offered one entrepreneur on the help-for-hire site Fiverr, one of a multitude of similar pitches.

... Determining the number of fake reviews on the Web is difficult. But it is enough of a problem to attract a team of Cornell researchers, who recently published a paper about creating a computer algorithm for detecting fake reviewers. They were instantly approached by a dozen companies, including Amazon, Hilton, TripAdvisor and several specialist travel sites, all of which have a strong interest in limiting the spread of bogus reviews.

“The whole system falls apart if made-up reviews are given the same weight as honest ones,” said one of the researchers, Myle Ott. Among those seeking out Mr. Ott, a 22-year-old Ph.D. candidate in computer science, after the study was published was Google, which asked for his résumé, he said. ...

http://www.nytimes.com/2011/08/20/technology/finding-fake-reviews-online.html?_r=2&scp=1&sq=cornell%20yelp%20factories&st=cse