For some projects in my previous UX design job, I used NPS Score to measure UX design's success. Now, I found it was a mistake.

NPS stands for Net Promoter Score, a metric used in customer loyalty. In 2003, Fred Reichheld, a partner at Bain & Company, created a new way of measuring how well an organisation treats the people whose lives it affects—how well it generates relationships worthy of loyalty. Some critiques question whether the NPS is at all a reliable predictor of company growth. A google search can get you all the info if you need it. But as a designer, I say it's not the right tool for measuring design success, as customer loyalty is not customer experience.

I used it on my previous project just because it's available. But if we want to know how heavy a beer bottle is, we can't use a ruler to measure; even if you have a ruler in your hand. At that time, I didn't realise that.

Then the following question would be, how will you measure the success of a UX project? The short answer is, it depends... There's no one ruler for all, and NPS is definitely not the right tool.

This post was inspired by an article by the one and the only Jared Spool. Thanks, Jared, for all the great insights you shared!