In fact this broader context just strengthens the

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Unformatted text preview: ire product portfolio where products are released in many versions over a certain period. In fact, this broader context just strengthens the opinion for allocating extensive usability engineering resources as early as possible, as design decision made for any given product may have ripple effects due to the need for subsequent products and versions. Some usability engineering experts believe that human elements involvement in a particular product ultimately have their greatest impacts on future product releases. As a result, in order to plan the future versions, it is also a prime reason to follow up the release of a product with field studies of its actual use. Particularly for a company that sells software products in the open market, the usability of each product will contribute to the company’s general reputation as a quality software supplier, whereas, a single product with poor usability can cause brutal damage to the company sales. Nielsen (1993) has formed “usability engineering lifecycle model” which highlights that system developers should not rush straight into design, they have to first consider the usability recommendations to avoid the wastage of time and resources and avoid duplication and repetition of entire development work. In addition, usability work did before the system design also make it possible to avoid developing unnecessary system 29 features and options. The model given below can be used as a guide for system developers to effectively implement usability engineering methods. The usability engineering lifecycle model ______________________________________________________________________ 1. Know the user a. Individual user characteristics b. The user’s current and desired tasks c. Functional analysis d. The evolution of the user and the job 2. Competitive analysis 3. Setting usability goals. a. Financial impact analysis 4. Parallel design 5. Participatory design 6. Coordinated design of the total interface 7. Apply guidelines and heuristic analysis 8. Prototyping 9. Empirical testing 10. Iterative design a. Capture design rationale 11. Collect feedback from field use ______________________________________________________________________ Table 2.1 The stages of the usability engineering life cycle model. Source: (Nielsen, 1993) Page 72 According to Wichansky et al. (1988) many of the pre-design usability actions may be considered part of a market research or product planning process and may sometimes be conducted by marketing groups. However, conventional market research does not typically employ all the methods needed to properly inform usability design, and the results are often poorly communicated to programmers. Therefore, if management successfully integrates usability and marketing activities then the need for duplicate efforts could be controlled. One outcome of such integration can be the consideration of product usability attributes as features can be used by marketing to distinguish the product. In addition, marketing efforts based on usability studies can sell the product on the basis of its benefits as perceived by users rather than its features as perceived by system programmers. 30 2.7 Usability Requirements There are many ways to explain the concept of usability. The one of the best usability concept is defined by Gould (1985) that any system designed for people to use should be build by keeping in mind that it should be easy to learn and remember, it should be useful, it should contain functions that people really need in their work and be easy and enjoyable to use. In addition, the components of usability, which were identified Shackel et al., (1990) so that they could be tested and can be expressed in terms of 1. Learnability: The time and effort needed to reach a specified level of user performance. 2. Throughput: The tasks accomplished by experienced users, the speed of task completing and the errors made. 3. Flexibility: The level in which the system can accommodate changes to the tasks and environments ahead of those first specified. 4. Attitude: The positive attitude stimulated in users by the system. The usability requirements can be collected together with functional and data requirements using many of the traditional requirements gathering techniques such as interviews and observations. The activity of gathering usability requirements is generally known as usability study. Usability requirements are relates with user satisfaction and the overall performance and accomplishments of the system (Preece et al.,1995). Usability requirements could be expressed in term of performance measures known as usability metrics. The usability metrics could be illustrated by the usage, performance assessment and completion time for specified tasks by a specified group of users, the number of errors per task and the time spent on documentation usage. Tyldesley (1988) highlighted many factors that could be considered in developing usability metrics and specifications. He mentioned 22 possible measurement criteria...
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This document was uploaded on 12/31/2013.

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