رویکرد فازی برای اولویت بندی استفاده از تضاد های مورد نیاز: یک ارزیابی تجربی Fuzzy Approach to Prioritize Usability Requirements Conflicts: An Experimental Evaluation

I. INTRODUCTION The age of ergonomics exploration has drastically altered the consumer’s standards of product selection. Unlike our perception of history, now there is great emphasis placed on usability as an important user requirement. It is acknowledged that usability is an integral and important concern in the field of HCI. The first step towards a successful user centered development is the identification of the usability attributes (factors). These usability factors and sub-factors become the basis of usability requirements. These requirements can later be transformed into quantified usability specifications. Software quality factors that have been explored previously, are non-quantifiable [1]–[3]. It is of great importance to gather and compile the usability requirements of all concerned and identify quantitatively the inherent conflicts among them, along with the low level attributes. Equally important is to have these requirements identified at earliest for the convenience of analysis and implementation. The later, these requirements are identified, the more expensive and difficult becomes their analysis and implementation as usability may unknowingly impact software architecture design [4]. We also need to take into consideration the debate on how and why we can enhance usability. Lack of paying attention to such logics, acceptable solution cannot be achieved. Main concern with usability requirements (URs) is to identify the attributes of URs that are really needed by the users. Usability of a system can be improved by introducing usability attributes to evaluate the usability of a software system [5]. Making it more complex is the fact that the stakeholders, especially the users, do not have an idea about the usability requirements at an early stage. Some of the stakeholders consider one usability requirement important, but others think in different way resulting in emergence of conflicts. In most cases, previous experience can be helpful in making decisions about such conflicts. For example, A conflict among usability requirements can be seen while improving learnability (an attribute of usability), is to develop systems which can direct a user through step by step guidance. However, in some cases, the functionality of the system required to resolve a conflict can affect the overall efficiency in a negative way [6]. For example, easier to learn systems can be inefficient and harder to learn systems could be more efficient as shown in Fig. 1 [7]. Meeting all the requirements of a variety of stakeholders may not be possible at all times. The ranking of the requirements takes place after collection and analysis of requirements. It is highly recommended to use some software tool for conflict identification [8]. Natural strong interlinking between standard quality aspects [9] make it imperative to highlight it to satisfy all the stakeholders. In this paper, we have studied existing conflict resolution techniques for their applicability in our problem domain. Our study shows that an appropriate framework that could effectively prioritize conflicts among usability requirements and rank these conflicts is a need of the time. We have found that usability requirements are related to each other in such an intricate manner, that they have inherent conflicts. In order to develop more practical software systems it is highly needed to pay attention to this area.