Debunked many many times. Michael Luca at HBS is one such study. Sales at Yelp has no ability to influence reviews, and Yelp employees are not allowed to even write reviews anymore.<p><a href="http:&#x2F;&#x2F;officialblog.yelp.com&#x2F;2013&#x2F;12&#x2F;harvard-study-debunks-yelp-extortion-conspiracy-theory-yelp-doesnt-extort.html" rel="nofollow">http:&#x2F;&#x2F;officialblog.yelp.com&#x2F;2013&#x2F;12&#x2F;harvard-study-debunks-y...</a>