To determine the level of usability for a website, one or more usability experts “walk” through a set of the most typical user tasks supported by the website, one-step-at-a-time.
At each step in a task procedure, the evaluator(s) asks herself the following four questions about her expectations of users’ behaviors:
- Will the user try to achieve the right effect?
- Will the user notice that the correct action is available?
- Will the user associate the correct action with the effect to be achieved?
- If the correct action is performed, will the user see that progress is being made toward solution of the task?
The evaluator(s) attempts to come up with a “success story” for each step in the process. If she cannot come up with one, she instead creates a “failure story” and assesses why the user might not accomplish the task based on the interface design. These insights are then used to improve the usability of the website or application.