I have seen some companies define KPIs for their UX efforts based on metrics like the Net Promoter Score (NPS). However, having worked with many qualitative and quantitative metrics to try and model the overall UX for a product or service, it seems that the NPS is very much a sales and marketing driven metric, and that the part of UX it best represents is probably the utility (i.e. usefulness) of the product/service.

Looking at a simplified description of UX as being the usability, utility and engagement of the user when interacting with the product or service, can it be argued that the NPS is possibility more representative of the utility of the product or service since it is the most likely reason that someone would recommend it to another person.

2 Answers 2


Jeff Sauro has done a number of blog posts related to NPS and UX (http://www.measuringusability.com/blog/nps-ux.php). Based upon regression of SUS data with NPS, 30 to 50% of a user's likelihood to recommend a product is based upon the ease of use of the product.

  • 1
    +1 As stated NPS is a marketing driven metric. It just says how likely to recommend, but not why! UX metrics are the why. Take Facebook for instance: Utility close to zero, Usability is a nightmare, but engagement is very high. And people are very likely to recommend it. Business software is completely different. Here utility has the biggest impact of overall impression. NPS alone can't explain it, but taking UX metrics as helpers give you the needed insights. NPS is a deduction of combined UX metrics.
    – FrankL
    Aug 28, 2014 at 7:23

My view on this is rather different, but mainly as the definitions I use seem to be different than yours.

The UX Hierarchy of need

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  • Functionality
    • The set of tasks a user can perform on the system.
    • Often referred to as utility.
  • Reliability
    • How stable and consistent in performance the system is.
    • Bugs and downtime fall in here.
  • Usability
    • The amount of effort that has to be expended in order to perform a task.
    • Broken down to:
      • Cognitive effort:
        • Interpretation
        • Decision making (by the cognitive theories I believe in, decision making is not a separate process, but rather a high-level form of statistical resolution, which in evolved cases is highly conscious; but decision making has particular importance in UX so I include it here nevertheless).
      • Physical effort (mouse travel distance, click count, etc. will fall here).
  • Affectivity
    • The emotional, subconscious impression the system leaves on users.
    • Although in the illustration affectivity is shown as the 4th step, in practice it is the outcome of all other three (and marketing), and thus is really a wrapper to these.


Given the definitions above, NPS, in my view at least, is clearly part of affectivity.

An important thing to mention is that if you ask "How likely is it that you'll recommend this product to a friend or colleague?" and then follow it by "why?", most people's answer will fall into retrospective reasoning rather than an active one. In other words, the decision has been made first, only then reasons are 'made up' - which further supports the idea that it is emotions that play a part here.

I don't think NPS is any indicator of functionality or usability (and definitely not reliability).

  • A very interesting comparison of thoughts. As I mentioned in my question, I was using a 'simplified' or simplistic view of UX to make the discussion less complex. In your definition affectivity seems to map to engagement in my definition, which is a result of the usability and utility of the product/service. If NPS is not an indicator of functionality or usability, then why is affectivity the outcome of all other three previous steps?
    – Michael Lai
    Aug 27, 2014 at 1:31
  • You can argue that ones recommendation for a peer is the outcome of functionality, reliability and usability of the system, but one that is much more due to emotional response than a conscious reasonable one.
    – Izhaki
    Aug 27, 2014 at 9:12
  • Another way to look at the question might be why would someone not recommend a product/service to someone else, and I would say that if it is not reliable, useful or usable then it is highly unlikely that someone would recommend it to other people, since it would decrease their reputation as a credible source of information or advice.
    – Michael Lai
    Aug 28, 2014 at 6:27

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