Set Measurable Usability Goals

Topics on this Page

• Creating Measurable Usability Goals
• Measuring Your Usability Goals
• Examples of Measuring Usability Goals

Creating

To determine your site’s usability, you need to create measurable usability goals. Typical usability goals include time, accuracy, overall success, and satisfaction measures.

• Time: Set a goal for the overall time the user will need to carry out a task on your site. You can also break that down into separate goals for time to:
  • Get to the application or the right page
  • Use the application or understand the information
  • Recover from an error
• Accuracy: Set a goal for the accuracy with which the user carries out the task. You can also break it down into separate goals for the number of:
  • Unproductive navigation choices or searches
  • Errors in using an application
  • Misunderstandings of information
• Success: Set a goal to measure users’ success with your site. For example:
  • Identify an application new users will go to for help if they need it, find the help they need there, and get back to their original task within 2 minutes
  • Set a goal that repeat visitors be able to successfully complete a task without using the help feature
• Satisfaction: Set a goal that users are happy with their experience on your site. You can also set separate satisfaction goals for:
  • Navigation
  • Search
  • Content detail and language

A good way to set measurable usability goals is to observe users doing similar tasks or seeking similar information. You can also conduct a usability test of your current site. You should record data on potential measures including time, accuracy, success, and satisfaction. If users have problems during the test then set specific goals to improve each of the problem areas.

When you set usability goals, you cannot say, "the system response time is going to be very slow, so we will set our time goal to account for that slow response." Users will leave your site if it is too slow. You must set a goal that matches users' needs and expectations and find a design solution to improve system response time if that is going to keep you from meeting the usability goal.

If you are developing a Web application, your application must allow users to do their tasks at least as fast with as few errors and as much success and satisfaction as their current way of working. Ideally, it should let them be faster, more accurate, more successful, and more satisfied. Otherwise, they won't use it.

If you are developing an informational Web site, your site must outperform other ways users get the same information—phone, printed material, and other websites.

Measuring Your Usability Goals

Consider time, accuracy, and success as more important than satisfaction ratings when measuring your usability goals. If users give the site low ratings, you need to fix your site. However, if users give the site high ratings, you may not be getting a true picture.

In usability testing, we find that users often give high satisfaction ratings even when they have problems using a site. They may:

• Be blaming themselves for the problems
• Not want to hurt your feelings
• Be being polite rather than saying what they really think

Examples of Measuring Usability Goals

Web site level scenarios refer to overall site or performance goals. For example:

• 95% of customers will be able to find and order a product.
• 95% of physicians will be able to find, read, and understand the latest information on lung cancer treatments.
• 95% of travelers will be able to make their own airline reservations.
• All trained "service representatives" will be able to handle an average of 25 customer calls per hour.

Scenario level refers to two or more pages and addresses issues related to one major type of user interaction). For example:

• 90% of users will be able to find a specific article on thyroid cancer within three minutes.
• 90% of users will be able to read an "update" article on skin cancer in less than five minutes.
• 90% of users will be able to make an airline reservation in less than five minutes.

Page level is always within a page and is usually the homepage. For example:

• 90% of users will be able to find and click on a specified link within 15 seconds.
• 90% of users will be able to find and click on a specified graphic within two seconds.
• The page will download in five seconds or less on systems using a broadband connection.

Widget or control level refers to menus and selection tools. For example:

• 95% of users will be able to use the dropdown selection box to find and select a specific color.
• 95% of users will be able to use the alphabetical list to select information on lung cancer.
• 95% of users will be able to use radio buttons to make a selection.