What is the best way of formally expressing usability requirements?

usability requirements hci
alex77 picture alex77 · Feb 4, 2009 · Viewed 15.5k times · Source

I am writing a system requirements document and need to include non-functional requirements relating to the usability of the system, but am not sure of the best way to express this.

"The system shall be easy to use" seems a bit vague to me, and not testable. Are there any 'official' standards/guidelines that can be adhered to relating to the usability of a program?

Answer

GWLlosa picture GWLlosa · Feb 4, 2009

Usually, we try to hash out an application-specific definition of 'easy to use'. For example, for our current project, easy to use means:

-All delays in the system longer than .5 seconds will produce a dialog box that says "Please wait."

-It is possible to reach any given system function from the main window in less than 3 clicks.

-It is possible to accomplish any given task with just the keyboard, without the mouse.

-All buttons in the system will adhere to established button convention (link to established button convention regarding size, naming, position, etc.)

-All screens will have a help button. Each help button on a given screen must provide at least one 'topic' for each control on the screen.

-etc.

These sorts of things are testable, and taken together, constitute a 'pretty good' usability standard. That said, nothing substitutes for actual users trying it out.

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