## 2 Research Methodology
### Systematic Literature Review
#### 2.1.1 Planning the Review  
The review planning includes essential elements: research questions, data sources, search strings also called keywords, inclusion and exclusion criteria for articles, and quality criteria for article selection.  
a: Research Questions  
The establishment of questions is a vital element of SLR. The research questions drive the entire literature review methodology. The study questions for this study are as follows:  
**RQ1**: What are the challenges to CRM in GSD?
**RQ2**: What are the challenges in the Pakistan industry related to CRM in GSD?
**RQ3**: Is there any variance between the identified factors in the SLR and those in an empirical study?  
b: Data Sources  
An iterative approach was employed to explore different scientific databases, digital libraries, and filtered relevant articles data. These libraries were selected carefully based on present research and a recommendation suggested by [39]. The data sources covered in this research study are as follows:  
* IEEE Xplore Library;
* ACM Association for Computing Machinery;
* Google Scholar;
* Science Direct;
* Wiley Online Library.  
c: Search Strings  
In this study, we extracted keywords from existing literature based on the research questions to develop the search strings. Boolean \"AND\" and \"OR\" operators were used to integrate keywords into a search string. Online databases were explored using these strings: (\"Challenges\" OR \"Barriers\" OR \"Problems\" OR \"Factors\" OR \"Hurdles\" OR \"Difficulties\") AND (\"Customer Relationship Management\" OR \"CRM\") AND (\"Global Software Development\" OR \"GSD\" OR \"Distributed Software Development\" OR \"DSD\").  
d: Inclusion Criteria  
The inclusion criteria for this study are given as follows:  
* For this research, we considered all the studies which discussed CRM-related activities in GSD, specifically those concerning the barriers to CRM implementation. Studies with empirical study assessments were preferred.
* The selection of studies was based on the study types, such as conference or journal.
* The selection of studies was based on the publication years ranging from 2010 to 2022.
* Articles were selected based on the English language.  
e: Exclusion Criteria  
The research studies that met the below-defined criteria were excluded:* Reports written in other than English language and lacking full-text availability were excluded.
* In addition, articles and reports that did not examine CRM in the global software environment were also eliminated from the study.
* Articles that discussed barriers other than CRM in GSD were also excluded from the analysis.
* The duplications of the same studies were excluded.
* Book chapters, blogs, and white papers were excluded.  
f: Quality Criteria for Study Selection  
The selected articles were assessed to determine their quality simultaneously with other phases such as information, evidence, and statistics gathering. A quality checklist was generated to qualitatively and quantitatively assess the selected data. An informal external review was also carried out to confirm the quality sufficiency of selected articles. The following guidelines [35] were kept in mind while developing this checklist. The quality assessment checklist is given as follows:  
**QA checklist questions:**  
* **QA1**: Does the study approach respond to research questions?
* **QA2**: Does the researcher examine the barriers of GSD?
* **QA3**: Does the study discuss CRM in the GSD environment?
* **QA4**: Are the findings presented in the study?  
For each given question **Q1** to **Q5**, the evaluation was performed as follows:  
* Studies that addressed all the research questions were marked with a score of point 1.
* A score of 0.5 was given to the studies addressing incomplete answers to questions.
* Studies that failed to address any of the given questions were marked with 0 score points.