Thoughts | Fixing the usefulness equation

This is a nit :)

As I dive into the Norman / Nielsen group’s work, I have mounting respect for what the organization has accomplished and the trove of knowledge it provides. This is a nit on Nielsen’s take on Usefulness.

Nielsen > Usefulness = Utility + Usability
Suggestion > Usefulness = Utility x Usability

By utility, Nielsen means “does it solve a real user problem?”. By usability, he means “can people understand, learn and efficiently operate the interface?”.

The plus + sign does not capture the depth of his idea in his equation. A multiplication sign x would do a better job. Indeed:

If an application is not usable at all (so if it’s usability is equal to 0), it is no longer useful and people will not use it however much value it provides. Similarly, if an application is highly usable but has no utility (people don’t perceive any value), people will stop using it.