The calculation for a net promoter score is percentage of "promoters" minus percentage of "detractors." Promoters are those individuals who help a company grow through loyal participation and referrals. Detractors are those individuals who damage a company's reputation through negative word of mouth.
The net promoter score alone cannot guarantee a company's success, nor does it determine a company's longevity. Companies must use the data obtained to implement programs that increase consumer satisfaction by actively engaging the customers. The real test of whether a company will grow or perish is whether it is making use of feedback to direct how the company develops.
A net promoter score is a useful tool, however. It can be used to measure a company's current success, which in turn correlates to continued success. This can then be used when making decisions on expansion, downsizing, purchases and other essential operations.
According to the Net Promoter System, Bain analysis shows that the net promoter score has continuously measured twice as high in companies that achieve long-term success over the average company.
There is a third population that is equally as important to a company as promoters and detractors, though they are not measured in the net promoter score: the "passives." These individuals are not as enthusiastically loyal to a company as promoters, and while they are satisfied with the services received, they are also amenable to competitors. Retaining this population and converting them to promoters is another step toward a company's success.