25. What is Usability? Several formal and informal definitions of usability exist. The most widely recognized is probably the ISO definition: The usability of an interface is a measure of the effectiveness, efficiency and satisfaction with which specified users can achieve specified goals in a particular environment with that interface. Usability is the ease of use and learnability of a human-made object.
36. Lack of Usability Although the definition of usability may be the subject of some discussion, lack of usability is readily recognizable. Systems that lack usability are characterized by: Existence of workarounds - because the interface is difficult or does not match workflow in the real world, users develop workarounds to compensate for the inadequacies of the system Low usage levels - Users use the system as little as possible. Dissatisfaction - Users, and particularly novices, will find the system difficult or frustrating to use Rework or double-handling - Inefficient design often means that the same data may need to be entered or read more often than is necessary. Because incorporating usability is a quality activity, it often occurs that systems with poor usability are also deficient in other areas. For example, they are likely to be crash-prone, poorly documented and difficult to maintain.
55. High Fidelity PrototypesOnce Design Strategy is completed, Execution stage take place with following methods, 1. Task flow Analysis 2. Navigation Structure 3. Information Architecture 4. Wireframes and 5. Low Fidelity & High Fidelity Prototypes
66. Heuristic Evaluation Heuristic evaluation is the most popular of the usability inspection methods. Heuristic evaluation is done as a systematic inspection of a user interface design for usability. The goal of heuristic evaluation is to find the usability problems in the design so that they can be attended to as part of an iterative design process. Heuristic evaluation involves having a small set of evaluators examine the interface and judge its compliance with recognized usability principles (the "heuristics"). By Jakob Nielsen 1. Visibility of system status 2. Match between system and the real world 3. User control and freedom 4. Consistency and standards 5. Error prevention . 6. Recognition rather than recall 7. Flexibility and efficiency of use 8. Aesthetic and minimalist design 9. Help users recognize, diagnose, and recover from errors 10. Help and documentation