Laws of Usability Testing [Steve Krug]

  1. There is no one “right” answer to most usability questions. Design is a complicated process and the real answer to most of the questions depends on multiple factors.
  2. There are a few useful guiding principles though.
  3. Definition of Usability: A person of average (or even below average) ability and experience can figure out how to use the thing to accomplish something without it being more trouble than it’s worth.
  4. Law #1 : Don’t make users think. The point is that every other things adds to our cognitive workload, distracting our attention from the task at hand. The distractions may be slight but they add up, especially if it’s something we do all the time like deciding what to click on.
  5. Your goal should be for each page or screen to be self-evident, so that just by looking at it the average user will know what it is and how to use it. In other words, they’ll “get it” without having to think about it.
  6. If you can’t make something self-evident, you at least need to make it self-explanatory.
  7. Facts of Life #1 : People tend to spend very little time reading most Web pages. Instead, we scan (or skim) them, looking for words or phrases that catch our eye. Exception: News, Reports, Stories, etc.
  8. Facts of Life #2 : When we’re designing pages, we tend to assume that users will scan the page, consider all of the available options, and choose the best one. In reality, though, most of the time we don’t choose the best option — we choose the first reasonable option, a strategy known as satisficing.
  9. Facts of Life #3 : Faced with any sort of technology, very few people take the time to read instructions. Instead, we forge ahead and muddle through, making up our own vaguely plausible stories about what we’re doing and why it works.
  10. Clarity trumps consistency. If you can make something significantly clearer by making it slightly inconsistent, choose in favor of clarity.
  11. Create effective visual hierarchies. But when a page doesn’t have a clear visual hierarchy — if everything looks equally important, for instance — we’re reduced to the much slower process of scanning the page for revealing words and phrases and then trying to form our own sense of what’s important and how things are organized. It’s a lot more work.
  12. Format text to support scanning.
  13. Law # 2 : It doesn’t matter how many times I have to click, as long as each click is a mindless, unambiguous choice. In general, it’s safe to say that users don’t mind a lot of clicks as long as each click is painless and they have continued confidence that they’re on the right track — following what’s often called the “scent of information.”
  14. Law #3 : Omit needless words. Get rid of half the words on each page. Then get rid of half of what’s left.
  15. Convey the big picture in the home page.
  16. All web users are unique and all web usage is basically idiosyncratic. Average user is a myth.
  17. Focus groups are best used in the initial planning stages of a project. Usability tests, on the other hand, should be used throughout the entire process.
  18. Testing one user early in the project is better than testing 50 near the end.
  19. Get buy-ins from various stakeholders for observing usability sessions.
  20. For each round of testing, come up with various tasks for the users to complete.
  21. During the user testing, it’s crucial that you let them work on their own and don’t do or say anything to influence them. Don’t ask them leading questions, and don’t give them any clues or assistance unless they’re hopelessly stuck or extremely frustrated. If they ask for help, just say something like “What would you do if I wasn’t here?”
  22. Attributes of usable stuff: Useful, Learnable, Memorable, Effective, Efficient, Desirable and Delightful.




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