什么— Definition of Usability
Usability is a质量属性that assesses how easy user interfaces are to use. The word "usability" also refers to methods for improving ease-of-use during the design process.
Usability is defined by5质量零件：
- Memorability：When users return to the design after a period of not using it, how easily can they reestablish proficiency?
- Errors： 多少errors用户是否使这些错误有多严重，它们有多容易从错误中恢复？
There are many other important quality attributes. A key one is公用事业那which refers to the design's functionality: Does it do what users need?
- 定义Utility=它是否提供features you need。
- 定义Usability=怎么easy & pleasant这些功能要使用。
- 定义Useful=usability + utility。
在网上，可用性是生存的必要条件。如果一个网站很难使用，人们离开。如果是homepage未能清楚地说明公司提供的内容以及用户可以在网站上做些什么离开。如果用户在网站上丢失，他们离开。If a website's information is hard to read or doesn't answer users' key questions, they离开。Note a pattern here? There's no such thing as a user reading a website manual or otherwise spending much time trying to figure out an interface. There are plenty of other websites available; leaving is the first line of defense when users encounter a difficulty.
The first law ofecommerce是,if users cannotfindthe product, they cannot买it either.
为了intranets，可用性是一个问题员工生产力。Time users waste being lost on your intranet or pondering difficult instructions is money you waste by paying them to be at work without getting work done.
Current best practices call for spending about10% of a design project's budgeton usability. On average, this will more than双人网站所需的质量指标（屈服于A.改进分数2.6），略低于Intranet的质量指标。对于软件和物理产品，当您在设计过程中强调可用性时，改善通常更小 - 但仍然很大程度上。
为了internal design projects, think of doubling usability as cutting training budgets in half and doubling the number of transactions employees perform per hour. For external designs, think of doubling sales, doubling the number of registered users or customer leads, or doubling whatever other KPI (key performance indicator) motivated your design project.
如何to Improve Usability
There are many methods for studying usability, but the most basic and useful isuser testing那which has 3 components:
- Get hold of some代表用户那such as customers for an ecommerce site or employees for an intranet (in the latter case, they should work outside your department).
- 要求用户执行representative tasks随着设计。
- 观察用户在哪里成功的地方，以及用户界面的困难。闭嘴let the users do the talking。
单独测试用户,让是很重要的them solve any problems on their own. If you help them or direct their attention to any particular part of the screen, you have contaminated the test results.
To identify a design's most important usability problems,testing 5 usersis typically enough. Rather than run a big, expensive study, it's a better use of resources to run many small tests and revise the design between each one so you can fix the usability flaws as you identify them.迭代设计is the best way to increase the quality of user experience. The more versions and interface ideas you test with users, the better.
User testing is different from专门小组那which are a poor way of evaluating design usability. Focus groups have a place in market research, but to evaluate interaction designs you must closely observe individual users as they perform tasks with the user interface.Listening to what people say是误导性的：你必须观看他们实际做的事情。
Usability plays a role in each stage of the design process. The resulting need for multiple studies is one reason I recommend making individual studies fast and cheap. Here are the main steps:
- Before starting the new design那test the old design要确定您应该保留或强调的好的部分，以及给用户麻烦的坏部分。
- 除非你在内联网上工作，否则test your competitors' designsto get cheap data on a range of alternative interfaces that have similar features to your own. (If you work on an intranet, read theintranet design annual从其他设计中学习。）
- 进行A.field studyto see how users behave in their natural habitat.
- 制作paper prototypesof one or more new design ideas and测试它们。您在这些设计思想中投入的时间越好，因为您需要根据测试结果改变它们。
- 优化最佳测试的设计理念multiple iterations，逐渐从低保真原型转移到计算机上运行的高保真表示。测试每次迭代。
- 检查设计相对1Manbetx 无论是来自您自己之前的研究还是发表的研究。
- Once you decide on and implement thefinal design那test it again. Subtle usability problems always creep in during implementation.
Don't defer user testing until you have a fully implemented design. If you do, it will be impossible to fix the vast majority of the critical usability problems that the test uncovers. Many of these problems are likely to be structural, and fixing them would require major rearchitecting.
The only way to a high-quality user experience is to start user testing early in the design process and to keep testing every step of the way.
If you run at leastone user study per week，值得构建专用的可用性实验室。然而，对于大多数公司来说，在会议室或办公室进行测试是很好的 - 只要您可以关注门以防止分心。重要的是你掌握了真正的用户，在使用设计时坐在他们身边。记事本是您需要的唯一设备。