250 words with 2 reputable sources cited and referenced 

 Bain & Company invented the Net Promoter System, and this system continues to be the leader in how companies earn customer loyalty and inspire employees. What is the Net Promoter Score? How is it calculated? What do promoter, passive, and detracting customer mean? Identify an industry, and compare three competitors in that industry by their NPS score. What does this tell you?