I would call all of those points extremely obvious and hardly worth a whole study. If you have low ratings, of course you're tempted to get some fake positive

I would call all of those points extremely obvious and hardly worth a whole study. If you have low ratings, of course you're tempted to get some fake positive reviews. If you have a lot of reviews, adding a few positive ones will not affect the overall score much--it's a drop in the bucket. Chain restaurants, well, everyone knows what McDonald's is, what would they gain from posting fake reviews? Businesses that claim their Yelp page have more interest in Yelp? Shouldn't it be the other way around, businesses who have decided they're interested in Yelp will claim their page? Claiming your Yelp page is a sign that you care; businesses that do not care about Yelp will not commit review fraud. Who else would post negative fake reviews but competitors? I guess reputation management companies could post negative fake reviews in an attempt to drum up business. An increase in competition encourages more negative fake reviews? I mean, if a business has no competitors, who has an interest in posting fake reviews? This ties to #5, where competitors are the ones who post negative reviews. More competitors, more fraud.