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Concept

Usability

The extent to which specific people achieve their goals with a product, in a specific context, with effectiveness, efficiency, and satisfaction.

In Spanish
Usabilidad
Origin
Popularized by Nielsen (1993); defined in the ISO 9241-11 standard (1998)

What problem it addresses

Explains why two products that do the same thing can be very different to use.

An example

Two machines sell the same train ticket.

It works, but it is hardTicket!7 screensSmall buttons, seven steps, and an error
Seven screens, small buttons, and an error that forces you to start over. You get there, with effort.
It works and it is easyTicket3 screensThe most requested option in view, three steps
Three screens, the most requested option in plain sight, and the ticket on the first try. You get there without thinking.

Both machines do the same thing. The difference is how much effort it takes the person, and that is usability.

Why it happens

  1. Set who and what for, because usability depends on people, their goals, and their context.

  2. Check whether they succeed (effectiveness) and with how much effort (efficiency).

  3. And how they feel doing it (satisfaction).

Applications in design

  • Use it like this

    Define for whom and for which task you want something to be easy before measuring it.

  • Avoid

    Saying something is “usable” without saying for whom or for what.

  • Don’t fall for it

    Something working does not mean it is easy to use: measure the effort too.

3 measures

What the research says

The standard defines usability with them: effectiveness, efficiency, and satisfaction, always for specific people, goals, and context (ISO 9241-11, 1998).

Solid evidence. Nielsen (1993) breaks it down into five attributes: easy to learn, efficient, easy to remember, few errors, and satisfying.

Connections

Used in

Related to

Authors and works

  1. 1993

    Jakob Nielsen

    Described usability as several measurable attributes and methods to improve them.

  2. 1998

    ISO 9241-11

    Set the definition in an international standard.

Sources

Original sources

  • International Organization for Standardization (1998). ISO 9241-11:1998. Ergonomic requirements for office work with visual display terminals (VDTs) — Part 11: Guidance on usability. ISO. (Withdrawn in 2018 and replaced by ISO 9241-11:2018). View source: International Organization for Standardization (1998)
  • Nielsen, J. (1993). Usability engineering. Academic Press.

Last reviewed: