## 3 Research Model and Hypotheses  
The initial development of a software customization model for SaaS quality was performed using systematic mapping [23]. Then, the model was refined iteratively based on the results of two rounds of content validity determination using SaaS expertise derived from academia, and internal consistency reliability testing conducted with software engineering researchers [24]. Drawing on [PERSON] et al. [24], the model consists of 6 constructs and 44 items. These 6 constructs and their associated items are: (1) configuration (8 items), (2) composition (4 items), (3) extension (6 items), (4) integration (8 items), (5) modification (5 items), and (6) SaaS quality (13 Items). A detailed description of model used in this study can be found in the Supplementary Materials.  
At the same time, there is a dearth of empirical evidence about the impact of software customization specifically on SaaS quality; thus, the research hypotheses were formulated based on (1) the literature review presented in this study, (2) the results of pre-conducted systematic mapping study [23], which showed the importance of considering SaaS quality when proposing customization solutions, and (3) reviews and studies on other software-related areas such as software changes. In this study, customization is conceptualized as changes made to SaaS application in order to address specific tenant requirements. Thus, customization could be considered by selection within predefined settings (configuration), combining application components (composition), inserting custom code (extension), implementing third-party components (integration), or alteration of the source code of the application (modification).  
Taking into account the fact that tenant requirements evolve, often after the development of applications and services, run-time customization capability must be provided for the tenant [1,9,10]. Moreover, customization capability must address the challenge of changing user requirements by facilitating ongoing updates of software to meet and satisfy user requirements over a system's lifetime [21,22]. Software customization caters explicitly to the propensity of the tenants' base to evolve to higher sophistication levels which demand powerful features to fulfil their requirements.  
Conversely, it is found that most changes are requested to enhance the quality and functionality of systems [19,21,58]. For instance, the database customization has a positive impact on the software functionality, whereas the source code customization has a positive impact on the usability and maintainability [19]. Generally, any customization is expected to affect the quality of any software product [19]. Accordingly, two-tailed hypotheses have been formulated as follows:  
**Hypothesis 1 (H1)**.: _Software configuration significantly influences the quality of SaaS application._
**Hypothesis 2 (H2)**.: _Software composition significantly influences the quality of SaaS application._
**Hypothesis 3 (H3)**.: _Software extension significantly influences the quality of SaaS application._
**Hypothesis 4 (H4)**.: _Software integration significantly influences the quality of SaaS application._
**Hypothesis 5 (H5)**.: _Software modification significantly influences the quality of SaaS application._  
Based on the literature review and the facts discussed above, and the findings of our pr-conducted studies [23,24], a research model was developed, depicted in Figure 1.