Setting measurable usability goals will help your team to assess the performance of your site throughout development.
Whether your assessment is at the beginning of the process, throughout iterative wireframe testing, after release, or all of the above, benchmarking and improving on task performance can only improve the usability of your site.
Measuring Top Task Completion
The most effective usability goals measure the ability for users to complete top tasks when visiting your site. Top tasks can be identified in a number of ways, including through task analysis and metrics analysis, among other ways.
Typical usability goals include speed, accuracy, overall success, or satisfaction measures.
|Goal||What it Measures||Example Benchmark|
|Speed||How long it takes to complete the task||95% of users will be able to use the alphabetical list to find terms in the glossary in under 2 minutes|
|Accuracy||The number of attempts to complete the task||95% of users will be able to locate the latest blog with less than 2 false clicks|
|Overall Success||The percentage of visitors who completed the task||90% of users will be able to find the Usability Guidelines database|
|Satisfaction||How satisfied the visitor was with the process of completing the task||95% of users will rate the experience of using Usability.gov a four or five on a one to five scale where five is the best.|
Assessing Goals at Various Levels
To know which level to assess the goal at, you need to consider how many pages the task affects and whether there are specific interactions associated. Usability goals can be assessed at the website level, scenario level, or the page level:
|Website level||Scenario level||Page Level|
Web site level goals refer to overall site or performance goals.
Scenario level goals refer to two or more pages and addresses issues related to one major type of user interaction.
Page level goals are always within a single page and usually focus on the homepage.
Satisfaction will always be a component of the user experience, but when you are examining usability goals, satisfaction could be considered either a symptom or an effect of poor usability in other areas, and is therefore lower priority goal for a website. If visitors can accurately and quickly complete their top tasks, satisfaction will naturally follow.
Make it a Team Effort
When establishing your usability goals, be sure to discuss them with your team. Their input will help clarify the goals, assure they are measurable, and may even lead to the correction of smaller or more easily addressed issues -- the low hanging fruit -- before you start collecting your usability data.
A possible format for documenting Measurable Usability Goals has been included in the template section of Usability.gov.