A market research metric based on a single survey question: 'On a scale of 0-10, how likely are you to recommend us to a friend?'
Why it matters: NPS is a proxy for customer satisfaction and word-of-mouth growth. Scores above 50 are excellent. Above 70 is world-class.
In practice: Promoters (score 9-10) minus Detractors (score 0-6). If 60% are promoters and 10% are detractors, the NPS is 50.