In September 2011, Boston University and Harvard students released a study suggesting that running a Groupon promotion lowers a merchant’s Yelp rating. Their finding left us wondering two things: why does this relationship exist, and what, if anything, can restaurants do to minimize these negative effects? To address this, we researched why by analyzing 736 Yelp restaurant reviews across 75 restaurants where the reviewer cited using a deal voucher.

Our findings were consistent with the above study in that Yelp ratings suffer when merchants run “daily deal” promotions:Two theories could explain why deal-diners write harsher Yelp reviews: Deal-diners are more demanding (and troll-like) than normal diners; the circumstances of running a “daily deal” promotion creates potential customer experience problems that otherwise would not exist.