E-Mail EVANSTON, Ill. -- Five-star ratings are no guarantee to lead you to the perfect barber who truly understands your hair or to the espresso machine that brews a perfect cup of coffee. That's because most products online are now rated positively, making it harder than ever to truly discern whether they will succeed in the marketplace. A new study from Northwestern University Kellogg School of Management and the University of Massachusetts Boston was able to predict the success of movies, commercials, books and restaurants by relying on the "emotionality" of reviews instead of the star rating. The researchers explored box office revenue of 2,400 movies, sales of 1.6 million books and real-world reservations at more than 1,000 restaurants. In their analysis, emotion reigned supreme; in fact, higher star ratings were either a weaker signal of success or negatively related to success.