NPS reminds me of Mencken's "to every complex problem there is an answer that is simple, obvious, and wrong". I'm amazed any business school could spend weeks on this. I'm equally amazed that anybody treats it as anything but a crude tool. If someone rates you 6 they are treated the same as someone rating you 1. But to most people 6 is at least slight approval. The fact that there have been no studies showing it actually correlates with anything useful is another factor to consider. And, as another poster commented, it just doesn't work in some places. I'm incredibly unlikely to actually recommend any organization unless they have done an absolutely stunning job. Which most simply do not. The whole thing has a strong smell of bovine manure.