1993 customizability customizability is the ability

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Unformatted text preview: the user’s head, substitutivity can control user errors and cognitive effort (Dix et al., 1993). Customizability Customizability is the ability of modification of the user interface by the user or the system. This ability concerned with the automatic modification that the system would make based on user knowledge. It is important to distinguish the difference between the user-initiated and system-initiated modifications, associated with the former as adaptability and the later as adaptively (Dix et al., 1993). Adaptability associates to the user’s ability to adjust the input into output. This customization may be very limited, that the user just allowed adjusting the position of soft buttons on the screen, or redefining command names. Adaptively is the automatic customization of the user interface by the system however decisions for adaptation could be based on user capability or observed replication of certain task sequences. The difference between adaptively and adaptability is that the user plays an explicit role in adaptability but his role in an adaptive interface is more implied (Dix et al., 1993). 2.5.3 Robustness A user engaged with a computer in order to achieve some goals in that specific business domain. The robustness of that interaction comprises features that support the successful achievement and assessment of the goals. Here, we will discuss the principles which support robustness. 27 Observability Observability refers to allow the user to assess the internal state of the system by perceivable representation at the interface. Observability permits the user to compare the current observed state with his intention and within the task action plan with a possibly to lead plan revision. In addition, there are five other principles e.g. browsability, defaults, reachability, persistence and operation visibility which greatly helps to understand observability (Dix et al., 1993). Recoverability The users mistakes while using a system which they want to recover are called recoverability. Recoverability allows user to reach their desired goal after recognizing errors in previous interaction. There are two ways in which recovery can be made, forward and backward. Forward error recovery covers the current state and negotiation from that state toward the desired state. Forward error recovery could be the only possibility for recovery if the effects of interaction are not revocable. Backward error recovery is a way to undo the effects of earlier interaction in order to return to a prior state before proceeding. For example, in word-processing, a mistyped keystroke may wipe out a large section of text which user want to retrieve by an equally simple undo button (Dix et al., 1993). Responsiveness Responsiveness is the ability to measures the rate of communication between the system and the user. Response time is generally the duration of time needed by the system to express state changes to the user. In overall, short duration and instantaneous response times are desired. Here, instantaneous means that the user perceives system should react immediately. However, even in such situations when an instantaneous response is not obtained, there must be some hint to the user that the system has received the request and working on request (Dix et al., 1993). Task conformance Task conformance refers to the extent the system provides services to all of the tasks the user wants to perform and the way the user understands them. Task conformance deal with the coverage issues and task adequacy focus on the users understanding of the tasks (Dix et al., 1993). 28 2.6 Usability Engineering The principle of usability engineering approach is to know the exact criteria, which can be used to assess a product for its usability. The user experience about a specific product is the ultimate key to measurement the usability of that product. Since, a user’s hand on experience with an interactive system is at the physical interface; therefore the focus on the actual user interface is logical. With reference to software development life cycle, one of the significant features of usability engineering is the addition of a usability specification and formatting the requirement specification that focus on features of the user-system interaction which contribute to the usability of the product (Dix et al., 1993). The key feature of usability engineering is the assertion of clear usability metrics early in the design process, which can be used to assess a system when it is delivered. There is a logical and solid reason which point out that it is only through empirical approaches that can be use with usability metrics that we can reliably build more practical systems. However, the ultimate standard for determining usability might be by observing user performance, although this does not mean that these measurements are the best way to produce a predictive design process for usability (Dix et al., 1993). According to Grudin et al. (1989) usability applies to the growth and expansion of ent...
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This document was uploaded on 12/31/2013.

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