## 4 SLR Methodology
### Conducting the SLR
#### 4.2.1 Identifying Potential Research Articles  
Inclusion and exclusion criteria were determined to identify potential research articles and are presented in Table 1. The criteria for inclusion in the SLR were peer-reviewed articles on XAI written in the English language and published in peer-reviewed international conference proceedings and journals. The criteria for exclusion from the SLR were articles that were related to the philosophy of XAI and articles that were not published in any peer-reviewed conference proceedings or journals. Throughout the article selection process, these inclusion and exclusion criteria were considered. To ensure the credibility of the selected articles, a checklist was designed. The list contained 10 questions that were adapted from the guidelines for conducting an SLR by [PERSON] and [PERSON] et al. [38; 39]. Moreover, to facilitate the validation, the questions were categorised on the basis of design, conduct, analysis, and conclusion. The questions are outlined in Table 2. \begin{table}
\begin{tabular}{l l} \hline \hline
**Inclusion Criteria** & **Exclusion Criteria** \\ \hline Describing the methods of XAI & Describing the methods in different contexts than AI \\ Peer reviewed & Describing the concept/philosophy of XAI \\ Published in conferences/journals & Preprints and duplicates \\ Published from 2018 to June 2021 & Published in workshops \\ Written in English & Technical reports \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Inclusion and exclusion criteria for the selection of research articles. The process for identifying potential research articles included the identification, screening, eligibility, and sorting of the selected articles. A step-by-step flow diagram of this identification process is illustrated using the \"Preferred Reporting Items for Systematic Reviews and Meta-Analyses\" (PRISMA) diagram by [PERSON] et al. [40] in Figure 5. The process started in June 2021. An initial search was conducted using Google Scholar ([[https://scholar.google.com/](https://scholar.google.com/)]([https://scholar.google.com/](https://scholar.google.com/)) accessed on 30 June 2021) with the keyword _explainable artificial intelligence_ to assess the available sources of the research articles. The search results showed that most of the articles were extracted from SpringerLink ([[https://link.springer.com/](https://link.springer.com/)]([https://link.springer.com/](https://link.springer.com/)) accessed on 30 June 2021), Scopus ([[https://www.scopus.com/](https://www.scopus.com/)]([https://www.scopus.com/](https://www.scopus.com/)) accessed on 30 June 2021), IEEE Xplore ([[https://ieeexplore.ieee.org/](https://ieeexplore.ieee.org/)]([https://ieeexplore.ieee.org/](https://ieeexplore.ieee.org/)) accessed on 30 June 2021) and the ACM Digital Library ([[https://dl.acm.org/](https://dl.acm.org/)]([https://dl.acm.org/](https://dl.acm.org/)) accessed on 30 June 2021). Other similar sources were also present, but those were not considered since they primarily indexed data from the mentioned sources. Moreover, Google Scholar was not used for further article searches since it was observed that the results contained articles from diverse domains. In short, to narrow the search specifically to the AI domain, the mentioned databases were set to be the main sources of research articles for this review. Initially, 1709 articles were extracted from the bibliographic databases after searching with the keyword _explainable artificial intelligence_, as before. To focus this review on the recent research works, 113 articles were excluded because they were published before 2018. A total of 1596 articles were selected for screening, and after reviewing the titles or abstracts, more than half of the articles were excluded as they were not related to AI and XAI. From the 647 articles screened from the AI domain, 376 articles were excluded as they were duplicates or preprint versions of the articles.