These figures need to be seen for what they are: As a limited window into a customer relationship that consists of a wide variety of facets. CES and NPS illuminate various sections of this window and have an even stronger effect when combined. But to fully understand a customer relationship, a more thorough analysis is usually required - at least periodically.These figures need to be seen for what they are: As a limited window into a customer relationship that consists of a wide variety of facets. CES and NPS illuminate various sections of this window and have an even stronger effect when combined. But to fully understand a customer relationship, a more thorough analysis is usually required - at least periodically.