TASK CENTERED USER INTERFACE DESIGN A Practical Introduction
Throughout this book we've emphasized the importance of bringing users into the interface design process. However, as a designer you'll also need to evaluate the evolving design when no users are present. Users' time is almost never a free or unlimited resource. Most users have their own work to do, and they're able to devote only limited time to your project. When users do take time to look at your design, it should be as free as possible of problems. This is a courtesy to the users, who shouldn't have to waste time on trivial bugs that you could have caught earlier. It also helps build the users' respect for you as a professional, making it more likely that they will give the design effort serious attention. A second reason for evaluating a design without users is that a good evaluation can catch problems that an evaluation with only a few users may not reveal. The numbers tell the story here: An interface designed for a popular personal computer might be used by thousands of people, but it may be tested with only a few dozen users before beta release. Every user will have a slightly different set of problems, and the testing won't uncover problems that the few users tested don't have. It also won't uncover problems that users might have after they get more experience. An evaluation without users won't uncover all the problems either. But doing both kinds of evaluation significantly improves the chances of success.