Role of context in usability evaluations: A review <s> Physical Context <s> Abstract Previous research in software ergonomics has indicated the importance of evaluating the usability of computer user interfaces. This paper presents a quantitative basis for selecting from among multiple alternative interfaces relative to multiple criteria of usability concern. The proposed model consists of two main phases: the prescreening phase and the evaluation phase. The prescreening phase involves expert judgment-based assessment with qualitative criteria. The first phase uses absolute measurement analytic hierarchy process (AHP) to filter possible alternative interfaces to a reasonable subset. The evaluation phase involves user-based assessment such as user testing, with quantitative criteria. The objective of the second phase is to evaluate a subset of alternatives using objective measures and to select the best alternative. A set of criteria and measures for evaluating the usability of computer software designs is presented. The proposed methodology is demonstrated in the interface design of a database system used to analyze trip cases information of nuclear power plant. Relevance to industry There is currently a focus on the usability of interactive computer software. Software developers, interface designers or human factors engineers often confront the task of comparative evaluation among systems, versions or interface designs. The proposed methodology provides practitioners with a structured approach to select the best interface based on usability criteria and measures. <s> BIB001 </s> Role of context in usability evaluations: A review <s> Physical Context <s> This paper examines and reviews research methods applied within the field of mobile human-computer interaction. The purpose is to provide a snapshot of current practice for studying mobile HCI to identify shortcomings in the way research is conducted and to propose opportunities for future approaches. 102 publications on mobile human-computer interaction research were categorized in a matrix relating their research methods and purpose. The matrix revealed a number of significant trends with a clear bias towards building systems and evaluating them only in laboratory settings, if at all. Also, gaps in the distribution of research approaches and purposes were identified; action research, case studies, field studies and basic research being applied very infrequently. Consequently, we argue that the bias towards building systems and a lack of research for understanding design and use limits the development of cumulative knowledge on mobile human computer interaction. This in turn inhibits future development of the research field as a whole. <s> BIB002 </s> Role of context in usability evaluations: A review <s> Physical Context <s> The distinction between field and laboratory is classical in research methodology. In human-computer interaction, and in usability evaluation in particular, it has been a controversial topic for several years. The advent of mobile devices has revived this topic. Empirical studies that compare evaluations in the two settings are beginning to appear, but they provide very different results. This paper presents results from an experimental comparison of a field-based and a lab-based usability evaluation of a mobile system. The two evaluations were conducted in exactly the same way. The conclusion is that it is definitely worth the hassle to conduct usability evaluations in the field. In the field-based evaluation we identified significantly more usability problems and this setting revealed problems with interaction style and cognitive load that were not identified in the laboratory. <s> BIB003 </s> Role of context in usability evaluations: A review <s> Physical Context <s> Usability testing has traditionally been conducted in dedicated laboratory. Alternatively, field study can be an option to conduct the usability testing. As HCI researchers who work with children, we have experiences in conducting usability tests in both natural and laboratory environments. We tested two different children applications in two different environments: testing drawing applications at their preschool and testing an educational game in our usability laboratory. Thus, this paper highlights our experiences in conducting both usability tests. Although the literature suggests that laboratory and field studies should be done for two different purposes, our experiences have told us that we can actually integrate the steps of field studies into the guidelines for lab tests. These steps are particularly useful for the novice designers and researchers who have never done usability evaluations with children before. <s> BIB004
Physical context comprise of the physical surroundings of the users, it is the location, the place where usability evaluation takes place. Physical context usually refers to the environment in which user is tested. Natural environment is the location of actual use of the system being tested. Usability evaluation taking place in natural environment is called as the field testing. Artificial environment is the simulation of natural environment, sometimes referred to as the controlled environment. Usability evaluation carried out in artificial environment is also referred to as laboratory testing. Traditionally laboratory experiments are employed to evaluate the usability of computer systems, and to improve the understanding of usability. Laboratory testing takes place in a controlled environment with the experimenter in control of assignments of subjects, treatment variables and manipulation of variables. It is possible to employ facilities for collection of highquality data such as video recording of the display and user interaction BIB003 . Razak et al. BIB004 states that the evaluation done in the laboratory has several advantages. First, the conditions for conducting research can be controlled. Secondly, all the participants experience same setting leading to higher quality data. Laboratory studies allow the researchers to focus on specific phenomena of interest and facilitate good data collection. Laboratory testing has received both appreciation as well as criticism. The laboratory evaluations do not simulate the context when usability testing is done with mobile phones, because laboratory settings lack the desired ecological validity  . Even though the adequateness of laboratory evaluations is questioned, 71% of the mobile device evaluations were done in laboratory settings BIB002 . Similar claim also comes from Park & Lim BIB001 where they state that simulating the use settings is very hard, time consuming, expensive and lacks contextual factors. Field testing takes place in a more natural setting. An artificial setting supports control but lacks realism whereas a natural setting supplies realism but makes control more difficult  . Oh & Kim  claims that to test children requirements and issues with the everyday use of technology, field evaluation would be a better choice. This claim is also supported by Xu et al.  in search for evaluation methods for children's tangible technology, where they found that location plays a large part in how children behave, children felt more at ease and focused when they are at school.