Practitioners of NPS seem to agree that it is a revolutionary approach for gathering granular, timely feedback from customers. They also think that it's a useful process for integrating organizational structures with incentives so that front-line employees are eager to listen and respond. But as with any new approach to management, there are plenty of questions and issues that need to be addressed.

One recurrent source of confusion is my insistence on keeping NPS surveys extremely short, just two or three questions. A short survey seems impractical when we all know that determining the score is just the first step. We need to learn not only the absolute score but also what must be done to improve it. So naturally we want to ask more questions.

Let me make a distinction here between two types of diagnostic processes that companies can use to learn what actions they must take to improve their NPS results. The more common approach is what we call top-down, because it is geared to help headquarters staff and execs discover broad patterns and systemic issues that can be addressed at the corporate center. We believe this kind of research--surveys with lots of questions--can provide valuable insights on issues like strategic segmentation or competitive benchmarking. As you would expect, this kind of survey is a standard feature in most Bain client work.

Yet this sort of top-down research typically does little to change the priorities and behaviors of front-line employees in a sustainable way. That is why firms must also develop a bottom-up (aka "operational") survey process that is geared to the front line. This is the brilliance of the Enterprise Rent-A-Car process; each branch follows up with customers to learn what improvements are required. The same individuals whose behavior must change engage in conversations with customers to understand their score and what changes make sense. It is this bottom-up process that requires short surveys, correspondingly high response rates, and closed-loop accountability. The bottom-up survey is not a research process looking for statistical correlations; it is a conversation with a specific customer performed by an (appropriately trained) employee on the front line.

This operational, bottom-up feedback is a distinctive pillar of the NPS discipline, designed to reinforce front-line employee learning, organizational responsiveness, and accountability. It is indeed revolutionary to create such a feedback system where the front line is responsible for closing the loop with customers--and for taking action. But we badly need just such a revolution to make firms truly customer-centric.

So don't get caught up in the debate about whether it is OK to have surveys with more than a few questions. The answer depends on whether the survey is part of a top-down research process or a bottom-up operational process. Most companies need both approaches for different purposes. Also, don't get caught in the trap of merely adding the ultimate question to an existing, and already lengthy, research survey. Unless you have an operational feedback process as well, you'll have little opportunity for taking action to create more loyal customers.

Companies that do use both surveys, and that clearly distinguish between them, need to be alert to another source of confusion. The Net Promoter score tallied by their bottom-up operating survey will almost certainly differ from the NPS calculated from the top-down research-oriented surveys. The differences are due to sampling variations, lower response rates, timing of surveys, differing levels of anonymity, and different context. Without careful communication and definition, dueling NPS results can undercut the credibility of the operational NPS. My advice: refer only to the results of your bottom-up operational system as net promoter score. Call the top-down research survey results what they are: net promoter estimates.

I would welcome comments and ideas regarding the best language (or labels) to use so that we can minimize confusion. Top-down and bottom-up don't quite catch all of the salient issues.  So please help the NPS community with your suggestions.