Investigating the issues encountered for improving usability

Abstract

Human centered design (HCD) is a traditional human Factors and Ergonomics concept. About the end of last century (1999), HCD is firstly standardized as process. It is rare case that the HCD which is not academic system is continued to discuss. The reason is considered not to solve the issues by using HCD. The purpose of this study is to investigate degree of recognition and application for promoting installation of HCD process to interactive system development area for usability and to clarify the issues and propose ways to solve this HCD problem. The questionnaire results by about 600 developers shows that known ratio about HCD is about 58% and applied ratio for in known ratio is about 42% (152 developers). However, overall, only 23% are covered. If HCD is recognized, nearly half of it will be applied, so it is important to raise overall recognition. The ratio of upper phase, development phase and evaluation phase that requirement definition related usability are similar. However, the ratio of deciding usability requirement in upper phase is only 13%. The ratio of evaluating usability requirement before specification is only 10%. Though the ration of recognition for HCD is not so low, many developing areas cannot decide usability requirement before requirement definitions. It is guessed that almost developers do not know how to decide usability requirements.To confirm this question, the other study was carried out. The ratio of recognition for Common Industry Format for usability (CIF) is about 39%. The number of developers to apply CIF to development is about 90. It is only 14%. The CIF is the format for applying HCD process to development process which is standardized in ISO. This standard series is belonged in Standard series for software quality called SQuaRE (System and software Quality Requirement and Evaluation). As the range of recognition for SQuaRE series is about 43%, it is necessary to spread CIF to software development areas.To verify the effectiveness of CIF, CIF is applied to self-driving bus system. Firstly, a high-level description of the context of use shown in the context of use description (ISO/IEC 25063) was made for a usual bus and self-driving bus system, respectively. After that, use needs and user requirements were extracted based on high level description. This process shows that it is easy to extract user requirements before requirements decision phase by using the CIF. However, it is found that management level does not understand the importance for the role of upper phase activities by this time investigation. For this reason, it seems that the ratio of recognition of HCD. It is necessary for improving usability to spread HCD, CIF and SQuaRE much more.