Context Coverage in “Quality in Use Model” Shin’ichi fukuzumi RIKEN Center for Advanced Intelligence Project Tokyo, Japan Shin-ichi.fukuzumi@riken.jp Abstract—In ISO/IEC 25010, Quality in Use is mainly focused On the other hand, ISO 9241-11: 2018[3] which is one of to the use of operators who interact with product and system human-system interaction standards in ergonomics area directly. However, as workstyle using ICT (Information describes the concept of usability shown in Figure 2. As Communication Technology) product, system or service has usability definition is “extent to which a system, product or been changed, object of quality in use are also changed to not service can be used by specified users to achieve specified only direct users with simple direct interaction but also many goals with effectiveness, efficiency and satisfaction in a stakeholders and society which are influence on indirectly by specified context of use” in this standard, this figure explains someone use the product, system and service. When the concept that outcome of “use” under identified context of use is of quality in use has changed, the issue about dealing with usability which elements are effectiveness, efficiency and previous quality characteristics occurred. This paper focuses on context coverage which is one of quality characteristics in satisfaction. In this figure, “use” is emphasized. previous quality in use model and discuss the position of this characteristic. As proposal, this characteristic shall be removed because context is prerequisite for “use”. And as another proposal, this characteristic should be moved to product quality because coverage can be represented as a specification. (Abstract) Keywords- usability, software engineer, quality in use, context coverage I. INTRODUCTION Importance of usability has been considered in not only ergonomics area but also software engineering area[1]. Quality model in SQuaRE (System and software Quality Requirement and Evaluation) series which are dealt with in ISO/IEC JTC1SC7 defined effectiveness, efficiency, satisfaction freedom from risk and context coverage as Figure 2. Usability concept (ISO9241-11, modified)[3] elements of “Quality in Use”[2]. Figure 1 shows the Quality Comparing these two figures, it turns out that there are in Use model defined in ISO/IEC 25010. common elements, i.e., effectiveness, efficiency, satisfaction. As describes above, usability is parts of outcome of “use”, it can be found that Quality in Use model is also focused on “use”, that is direct interaction. In case of this, freedom from risk means influence on economy and health by using and context coverage means whether product, system or service can be used or not under initially explicitly identified context of use. Figure 1. Quality in Use model defined in ISO/IEC 25010 [2] II. CONTEXT COVERAGE In this figure, effectiveness, efficiency, satisfaction, Recently, as workstyle using ICT (Information freedom from risk and context coverage are quality Communication Technology) product, system or service has characteristics of Quality in Use Model defined in ISO/IEC been changed, object of quality in use shall be included not 25010[2]. only simple direct interaction but also many stakeholders and society which are influence on indirectly by someone use the Copyright © 2021 for this paper by its authors. Use permitted under Creative Commons License Attribution 4.0 International (CC BY 4.0). product, system and service. That is, ICT product, system or service users are not only direct users who interacts system and product directly but also indirect user who use output obtained by using ICT product, system or service. When object of quality in use is wider, the model has to be changed. Figure 3 shows the proposal quality in use model which expanded object range. Figure 4. Imagine of context coverage Figure 4 shows the imagine of context coverage, that is, the relationship between assumed all context of use (N) and each context of use which really can be used. In this figure, case 3 and case X are context which really cannot be used. So, degree of context coverage is (N-2)/N. However, as proposed quality in use model is focuses on affect and influence by use, contexts which can not be used are out of target. This means that assumed contexts are prerequisite. If context changes and target ICT product, system or service could not be used, quality in use could not be discussed because “use” is a prerequisite in quality in use. When considering “use”, a context of use is predefined. So, when context changes, the context is predefined context of use. Figure 3. Proposal Quality in Use model [4] This proposal model covers almost quality characteristics/ III. FUTURE DISCUSSION subcharacteristics defined in previous model [2]. However, Though context coverage does not include in the new only context coverage does not appear. The reason describes proposal quality in use model, its concept is important for below. previous model users. To solve this issue, one idea is to add In ISO/IEC 25010, “context coverage” is defined as this quality characteristic to product quality model. Whether follows, ICT product, system or service can be used under assumed “degree to which a product or system can be used with context or not is dependent on their specification. So, context effectiveness, efficiency, freedom from risk and satisfaction coverage can be one of quality characteristics or in both specified contexts of use and in contexts beyond those subcharacteristics in product quality. initially explicitly identified”. And this quality characteristics has two subcharacteristics. Their titles and definitions are as follows, REFERENCES - context completeness: degree to which a product or [1] Fukuzumi, S., Hirasawa, N., Wada, N., Komiyama, T. and Azuma:, system can be used with effectiveness, efficiency, T.: Proposal of Quality in Use in software Quality, Human-cimputer freedom from risk and satisfaction in all the specified Interaction design and user experience, pp431-438, 2020. contexts of use [2] ISO/IEC 25010: Systems and software engineering -Systems and software Quality Requirements and Evaluation (SQuaRE) — System - flexibility: degree to which a product or system can be and software quality, 2011 used with effectiveness, efficiency, freedom from risk [3] ISO9241-11: Ergonomics of human-system interaction –Part11: and satisfaction in contexts beyond those initially Usability for definition and concept (2018) specified in the requirement [4] Fukuzumi, S. and Wada, Noriko: : Quality in Use -Case Study for From these definitions, context coverage means whether Evaluation-, Human-Computer Interaction. Theory, Methods and target ICT product, system or service can be used or not under Tools, Thematic Area, HCI 2021, Held as Part of the 23rd HCI assumed context of use. International Conference, HCII 2021, Virtual Event, July 24–29, 2021, Proceedings, Part I, Editors: Kurosu, Masaaki (Ed.) pp.343-350, 2021. .