The Boston Consulting Group, a leading advisor on business strategy, surveyed 4,800 business owners to ascertain revenue impact Yelp has on small businesses. Business owners with a free Business Account reported USD 8,000 in annual revenue from Yelp customers. More important than this is the fact that the business’ who advertised online increased revenues at an average of USD 23000.

Research conducted by Nielsen further endorses how customers find Yelp as trustworthy, reliable and with quality reviews. Approximately 80% customers make a purchase after visiting a review site, which goes to show that review sites are probably the last mile in buyer journey.
When compared to other review sites Yelp fared the best. The results from a survey conducted by Nielsen and shared by Yelp prove that it referred to more often for all categories. In comparison with other review sites it was referred to:

4.5 times more often than Angie’s List and nearly 3 times more often than TripAdvisor as being the most influential review site when making final purchase decisions

Nearly 3 times more often than Angie’s List and nearly 1.5 times more often than TripAdvisor when ranking sites with the most trustworthy reviews 2.5 times more often than Angie’s List when choosing which sites have the best quality reviews

Source: Yelp Official Blog