# A Systematic Mapping of Quality Models for AI Systems, Software and Components
## 2 Background of the Study
### Traditional Software Quality Models  
Traditionally, software systems are constructed deductively, by writing down the rules that govern system behaviours as program code [22]. Similarly, [PERSON] and [PERSON] [23] stated that the traditional software is based on logical design and rules.  
This section discusses some previous studies of traditional software quality models such as [PERSON] [24], [PERSON] [25], [PERSON] [26], ISO 25010 [27], and [28; 29; 30; 31; 32; 33]. Firstly, [PERSON] [24] proposed a software quality model and categorized it from three perspectives: product operation, product revision, and product transition. The model contains several quality attributes: correctness, reliability, efficiency, integrity, usability, maintainability, flexibility, testability, portability, reusability, and interoperability.  
[PERSON] [25] improved [PERSON]'s quality model by proposing a quality model with quantitative evaluation. The model in that study contains the following quality attributes: portability, reliability, efficiency, usability, testability, understanding, and flexibility.  
[PERSON] [26] conducted a study on a quality model for conventional software. The study contains five quality characteristics, namely: functionality, usability, reliability, performance, and supportability. The main limitation of the study is that it is only limited to the quality characteristics of traditional software evaluation.  
ISO 25010 [27] is a leading quality model for assessing software products. The study contains eight quality characteristics for software products, namely, functional suitability, compatibility, performance efficiency, security, maintainability, portability, reliability, and usability.  
Furthermore, ISO 9126 is an international standard for assessing the quality of software products [28]. This standard contains one international standard, namely, ISO 9126-1 [28], and three technical reports, which are ISO TR 9126-2 [29], ISO TR 9126-3 [30], and ISO TR 9126-4 [31]. ISO 9126-1 contains external and internal quality characteristics and quality-in-use. External and internal quality characteristics are functionality, reliability, usability, efficiency, maintainability, and portability. Quality-in-use comprises four sub-characteristics, which are effectiveness, productivity, safety, and satisfaction. ISO TR 9126-2 contains external metrics for software products, while ISO TR 9126-3 contains internal metrics for software products. ISO TR 9126-4 contains quality-in-use metrics.  
Next, ISO/IEC 25000 is a series of standards used for the evaluation of software products and is also known as SQuaRE (System and Software Quality Requirements and Evaluation) [32]. ISO/IEC 25000 is an evolution of the ISO 9126 standard, which was used for software product evaluation. This standard contains four parts, namely, ISO/IEC 2501n, ISO/IEC 2502n, ISO/IEC 2503n, and lastly ISO/IEC 2504n.  
In addition, [PERSON] [33] presented a quality model for software products and processes. The model was organized into three models, namely, the implementation model, requirement model, and design model. The implementation model contains several quality characteristics, namely, functionality, reliability, efficiency, usability, process maturity, maintainability, portability, and reusability.  
Traditional software quality models such as [PERSON] [24], [PERSON] [25], [PERSON] [26], ISO 25010 [27], and [28; 29; 30; 31; 32; 33] were based on software system-level quality characteristics, but not at the component level [34]. For instance, fault tolerance quality characteristics typically evaluate at the system level, rather than the software component level. However, some quality characteristics are appropriate to measure software components, others are not [34]. The next section discusses in detail existing quality models of software components.