Useful Verses Usable

This is a discussion that you are not likely to read in usability texts – the topic of useful verse usability, and the value of each. Just recently I had a discussion with someone on just this topic. Furthermore, I have had numerous discussions with others and each time it surprises me that people often do not know the difference between the two and the value of each.

Useful and Usable

If you go to the dictionary, you will discover that “useful” means “to be of serviceable value, beneficial” and in addition “of practical use.” Pretty straight forward.

On the other hand, the definition of “usable” is “capable of being used” and “convenient and viable for use.” Also a straightforward definition.

However, if you probe more deeply into the definitions, you will note that “useful” is the first, necessary quality of a tool or system. It must be useful or why use it? Usable is a quality of a tool or system. However, it is not primary in relationship with the quality of the being “useful.” It is secondary. Necessary, yes, nevertheless, it is still secondary.

The usefulness as a quality of a tool or system is not addresses in HE-75, or any other usability standard that I have encountered. (If any one knows of a standard where usefulness is addressed, please add a comment to this discussion.) Usefulness is assumed.

However, I have learned that in the real world, the usefulness of any tool or system should not be assumed. It should be tested. Furthermore, with complex systems, the fundamental capabilities of a system or tool are often useful. However, not all of the capabilities of that system may be.

I direct experience with a remote monitoring system where the primary or fundamental capabilities of the system have clear use. However, with each release of this system, as more capabilities are added, the useless capabilities may be on the verge of out numbering the useful ones.

Bottom Line

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  Usefulness is always more important than usability. If it is not useful, it is fundamentally worthless or at best, excess baggage, and a drag on the actual and perceived quality of the tool or system.
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  Usefulness should never be assumed. It should be demonstrated. I know of too many projects where usefulness was not demonstrated. This lead to capabilities being developed that waste time and money, and can damage reputations.