-In ISO/IEC 25010, Quality in Use is mainly focused to the use of operators who interact with product and system directly. However, as workstyle using ICT (Information Communication Technology) product, system or service has been changed, object of quality in use are also changed to not only direct users with simple direct interaction but also many stakeholders and society which are influence on indirectly by someone use the product, system and service. When the concept of quality in use has changed, the issue about dealing with previous quality characteristics occurred. This paper focuses on context coverage which is one of quality characteristics in 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)
Importance of usability has been considered in not only
ergonomics area but also software engineering area[
In this figure, effectiveness, efficiency, satisfaction,
freedom from risk and context coverage are quality
characteristics of Quality in Use Model defined in ISO/IEC
25010[
On the other hand, ISO 9241-11: 2018[
II.
Recently, as workstyle using ICT (Information Communication Technology) product, system or service has been changed, object of quality in use shall be included not 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.
This proposal model covers almost quality characteristics/
subcharacteristics defined in previous model [
In ISO/IEC 25010, “context coverage” is defined as follows,
“degree to which a product or system can be used with effectiveness, efficiency, freedom from risk and satisfaction in both specified contexts of use and in contexts beyond those initially explicitly identified”.
And this quality characteristics has two subcharacteristics.
Their titles and definitions are as follows, - context completeness: degree to which a product or system can be used with effectiveness, efficiency, freedom from risk and satisfaction in all the specified contexts of use - flexibility: degree to which a product or system can be used with effectiveness, efficiency, freedom from risk and satisfaction in contexts beyond those initially specified in the requirement From these definitions, context coverage means whether target ICT product, system or service can be used or not under assumed context of use. 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.
III.
Though context coverage does not include in the new proposal quality in use model, its concept is important for previous model users. To solve this issue, one idea is to add this quality characteristic to product quality model. Whether ICT product, system or service can be used under assumed context or not is dependent on their specification. So, context coverage can be one of quality characteristics or subcharacteristics in product quality.