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Set Measurable Usability Goals
What is a measurable usability goal?A measurable usability goal is the definition of successful usability on your site for a specific set of users doing a specific task. Example: You are building a Web application for owners of small businesses to pay state withholding tax online. You might set these measurable usability goals:
What types of measurable usability goals should you set?Typical usability goals include:
Time You can set a usability goal for the overall time the user will take to carry out a task (scenario) on the site. You can also break down that time and set measurable usability goals for:
Accuracy Similarly, you can set a usability goal for the accuracy with which the user carries out the task (scenario) or you can break it down into separate goals for:
Overall success Obviously, the usability goal must be that users will be successful. If users cannot do their tasks or cannot get answers to their questions on your Web site, your Web site is failing those specific users for those specific tasks and questions. You may also set measurable usability goals for how users will get to that success. For example, you might set a measurable usability goal for a Web application that new users will go to the help if they need it, will find what they need in the help, and will be back doing their original task within two minutes. You might set a measurable usability goal that a user who has done the task in your Web application before will do it successfully a second time without using the help. Satisfaction Again, obviously, your measurable usability goal must be that users are happy. You can measure overall satisfaction. You can also break down satisfaction and set separate measurable usability goals for navigation, search, level of detail in the content, language of the content, and other specific factors. Which types of measure should you rely on most?When you test the Web site against your measurable usability goals, consider performance (time, accuracy, success) as more important than satisfaction ratings. If users give the site low ratings, the site needs to be fixed. If users give the site high ratings, you may not be getting a true picture. In usability testing, we often find that users give high satisfaction ratings even when they have had serious performance problems. They may be blaming themselves for the problems. They may not want to hurt your feelings. They may be being polite rather than saying what they really think. How do you set measurable usability goals?By observing users and by doing usability testing. Observing users A good way to set measurable usability goals is to observe users doing similar tasks or seeking similar information today. 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 Web sites. Doing usability testing You can also use Usability Testing to set measurable usability goals. Do a usability test of your current site. Take data on potential measures, including time, accuracy, success, and satisfaction. If users have problems, set specific goals to improve each of the aspects of usability. When you set measurable usability goals, you must focus on what is going to make users work effectively and efficiently and be satisfied. 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. More examples of measurable usability goalsHere are examples of measurable usability goals for different aspects of a Web site. Note that these are only examples. You must decide on the goals for your site based on your purposes, the site's users, their tasks, and their expectations. Web site level:
Scenario level (usually two or more pages—addresses issues related to one major type of user interaction):
Page level (always within a page, usually the homepage):
Widget level:
Next stepsIf you have already evaluated your current site, learned about your users, done task analysis, developed personas, written scenarios, and developed measurable usability goals, you are ready to Design. |
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