User testing shows a relationship between the time taken to complete a task and the satisfaction rating of the task, and the site overall.

Graph 1 shows user satisfaction rating against average task completion time. The results show an inverse correlation. This means the longer it  takes for a task to be completed, the lower the satisfaction rating will be for the website.

Sites that are quicker to navigate and complete tasks get rated higher. The results show a very clear line through the points on the graph. Hence, task completion rate is directly tied to site satisfaction, from 1 (impossible) to 4 (easy).

Graph 1: User tester satisfaction in task completion by average time taken to complete a task

Graph 1 plots average task satisfaction rating on the y-axis (vertical) against the average task completion time (in minutes) on the x-axis (horizontal).

Sites with longer task completion times are rated lower for satisfaction. Put simply, the presence of accessibility barriers slows users down and reduces their satisfaction with the site.

Given that task completion time can be objectively measured and the inverse correlation to satisfaction, it is reasonable to conclude that task completion time can be used as a measure of accessibility. Agencies could use task completion time as an indicator of site accessibility.

The correlation of satisfaction to task completion time is not a surprising finding, as it is similar to the findings of general usability studies. However, it does confirm that users with impairments are less satisfied with sites that take more time to complete tasks.