What is Systematic Literature Review?
  1. ​Systematic Literature Review (SLR) is a rigorous and systematic methodology employed to examine and analyse pre-existing scholarly literature pertaining to a certain area of research.
  2. It is comparable to undertaking an exhaustive inquiry into the existing body of literature pertaining to a particular topic. It facilitates the compilation of pertinent data and perspectives from a multitude of sources, including scholarly articles, novels, and research papers.
  3. The process entails a comprehensive and open evaluation of both qualitative and quantitative elements of the research, with the aim of assuring clarity and precision in assessing its overall structure.
  4. Extensive use in the life sciences, biomedical engineering, and medical intervention literature.
  5. SLRs' application extends beyond the field of medical and healthcare literature. 
Source: Karolinska Institutet University Library (2022). Systematic reviews [Evidence Based Pyramid] : https://kib.ki.se/en/search-evaluate/systematic-reviews
 
  • As illustrated in the diagram, SLRs provide significantly more persuasive evidence than alternative forms of literature reviews. An element contributing to this is the methodical and rigorous approach employed when carrying out an SLR. 
  • Particular criteria and methodologies must be rigorously adhered to in order to identify, select, and evaluate pertinent studies. SLR endeavours to mitigate bias and incorporate exclusively dependable, high-quality studies in the review.
  • Although alternative forms of reviews may encompass a greater number of articles, they frequently do not adhere to the same standard of meticulousness when it comes to study selection and evaluation. This may lead to the incorporation of studies that possess less robust methodologies or evidence, thereby compromising the overall dependability of the review's conclusions.
  • It may be inferred that placing a higher emphasis on quality rather than quantity is a fundamental attribute of systematic literature reviews (SLRs).
The Importance and Need of SLR?
The importance of conducting a systematic literature review can be summarized as follows:
  • To summarize the existing evidence concerning a treatment or a technology e.g. What are the potential benefits and challenges of implementing artificial intelligence in healthcare systems?
  • To investigate all available evidence that supports or refutes a particular topic of interest.
  • To identify any gaps in the current research in order to suggest areas for further improvement.
  • To provide a framework / background in order to appropriately position new research activities.
Why SLR and not Literature Review?
Systematic Literature Reviews (SLRs) vs. Traditional Reviews
  • When deciding between a systematic literature review and a traditional literature review, it's essential to consider the advantages of an SLR.
  • In traditional reviews, even experts in a field can introduce bias or differing opinions, potentially leading to skewed interpretations of existing evidence.
  • Personal bias or preferences can influence a researcher's selection of "related studies" in traditional reviews, potentially excluding important research with different perspectives or findings.
  • Unstructured or unsystematic literature reviews may overlook relevant studies due to the lack of a standardized approach for identifying and including all pertinent research.
  • These limitations underscore the importance of exploring alternative approaches like SLRs.
  • SLRs prioritize transparency, thoroughness, and the use of comprehensive search methods to reduce bias.
  • As a result, they offer a more trustworthy and unbiased summary of research evidence.
  • Considering an SLR can significantly contribute to making more reliable conclusions based on the available research.
How to Define Topic / Area of Interest?
Defining the topic or area of interest for a Systematic Literature Review (SLR) is a crucial first step in conducting a comprehensive and effective review.
 
Here are the steps to follow to define the topic or area of interest for an SLR:
 
1. Choose a topic
  • What are you interested in?
  • What do you want to learn more about?
  • In which area do you think you could make a contribution to your field?
2. Make sure you can phrase the topic as an answerable question
  • Narrow it down by formulating a specific research question.
Distinction Between SLR and Traditional Literature Reviews
  • A systematic literature review and a traditional literature review may seem similar because both involve summarizing existing literature on a specific topic.
  • To clarify the differences between these two approaches, consider the table below, which highlights distinctions in terms of their definitions, goals, research questions, components, authorship, timelines, requirements, and values.
  • In a Systematic Literature Review (SLR), thoroughness and organization are key. It begins with a well-defined research question, specific study selection criteria, and a comprehensive search across various databases. Only studies meeting the criteria are included, ensuring fairness and transparency.
  • In contrast, a traditional literature review is more like storytelling. It encompasses a wide range of sources, and there are no strict rules for inclusion or exclusion. Authors make decisions based on their own judgment and knowledge, making it a more personal and subjective process.
Problem Statement in Systematic Literature Review
A problem statement is a concise and clear articulation of the specific research problem or question that your systematic literature review aims to address.
The Purpose of a Problem Statement
In the context of a Systematic Literature Review (SLR), the purpose of a problem statement remains crucial and serves specific functions:
 
Defining Research Problem
  • It should clearly articulate the specific research problem or question that the review aims to address. 
  • It provides a clear focus for the study, helping both author and the readers understand the central issue that the study intend to investigate.
Contextualizing the Review
  • It provides context for the review by explaining why the research problem is important and relevant. 
  • Author should discuss the broader field of study and highlight any gaps or limitations in the existing research that the review will attempt to address.
Scope and Objectives
  • Helps outline the scope of your review. It defines the boundaries of the study, specifying the types of studies, articles, or literature sources that will be included and excluded. 
  • This clarity is essential to maintain consistency and transparency throughout the review.
Setting Research Questions
  • The problem statement often leads to the formulation of research questions.
  • These questions guide your literature search and data extraction process, ensuring that the author collect and analyze relevant information.
Steps to Identify Research Gaps
Identifying research gaps is a critical step in conducting a Systematic Literature Review (SLR). Research gaps help researcher to understand what aspects of a topic have not been sufficiently studied or where further research is needed. Here are the steps to identify research gaps in an SLR:
 
1. Defining Your Research Questions 
Start by defining your research questions.
 
2. Review Existing Literature
Thoroughly reviewing existing literature 
 
3. Analyze Research Limitations
Pay close attention to the limitations sections of the research papers you examine.
 
4. Look at Citations and References
Take a close look at the sources cited in the research papers you review.
General Structure of Problem Statement
A problem statement typically follows a structured format that helps clearly define the problem, its context, and its significance:
 
1. Concise statement of the research problem
Example: 
The rapid advancement of digital technology and the internet has transformed the landscape of library services and information access.
 
2. Provide context and justification for the problem
Example: 
In this digital age, libraries play a pivotal role in providing access to a vast array of electronic resources. However, it's imperative to understand how these technological shifts impact the traditional roles and services of libraries, as well as how they affect the user experience and accessibility of information.
 
3. Highlight the scope and objectives of your review
Example: 
This systematic literature review aims to explore and synthesize the existing body of research on the impact of digital technology on libraries. Specifically, it will investigate the evolving roles of libraries, changes in user behavior, and the challenges and opportunities presented by digitalization. By doing so, this review seeks to provide insights into how libraries can effectively adapt to meet the evolving needs of their patrons in the digital age.

It's important to tailor the structure and content of the problem statement to the specific requirements of the research or project, as well as the target audience. A well-structured problem statement sets the stage for effective problem-solving and research efforts.
 
What is a research question in an SLR?
What is a research question in an SLR?
A research question in an SLR is a concise and focused query that defines the core objective of your review.
 
Research questions:
  • The most important part of an SLR. The question drives the entire methodology.
  • The search process must identify primary studies that address the research questions.
  • The data extraction process must extract the data items needed to answer the research questions.
  • The data analysis process must synthesize the data in such a way that the data can be answered.
Defining a Research Questions with PICO
Defining a research question using the PICO framework is a structured approach commonly used in healthcare and clinical research to formulate clear, focused, and answerable research questions.
  • SLR aims to find answers to individual questions, or test a single hypothesis, therefore it is necessary to identify the key question that must be answered.
  • Specify clearly the questions that the SLR aims to answer.
  • Recommend using PICO as a guide (for EBL).
  • The question can be translated to PICO (Population, Intervention, Comparison, Outcome) format.
PICO stands for Population, Intervention, Comparison and Outcome.
 
Example:
Research question: In academic libraries, does the implementation of self-checkout kiosks compared to traditional staff-assisted checkout result in shorter waiting times and increased patron satisfaction?
Population: Academic libraries patron 
Intervention: Implementation of self-checkout kiosks 
Comparison: Traditional staff-assisted checkout 
Outcome: Shorter waiting times and increased patron satisfaction
Defining a Research Questions with PICO
While the PICO (Patient/Population, Intervention, Comparison, Outcome) framework is commonly used in healthcare and clinical research, the PICO (Population, Interest, Context) framework can be particularly useful in qualitative research and research that focuses on more descriptive or exploratory inquiries. Here's how to define a research question using the PICO framework:
 
PATIENT : Who is Involved                   PATIENT : Elderly with Type 2 diabetes         
INTEREST : What's the Focus              INTEREST : Medication's impact on blood sugar
CONTEXT : Where and When              CONTEXT : Community healthcare setting
 
Example:
'In elderly patients with Type 2 diabetes, does Medication X improve blood sugar control compared to standard treatment in a community healthcare setting in 2023?’
Defining a Research Questions with SPIDER
The SPIDER (Sample, Phenomenon of Interest, Design, Evaluation, Research type) framework is another approach, mainly used in qualitative and mixed-methods research, for defining research questions that focus on qualitative and descriptive aspects. Here's how to define a research question using the SPIDER framework:
 
SAMPLE (S) - PHENOMENON OF INTEREST (PI) - DESIGN (D) - EVALUATION (E) - RESEARCH TYPE (R)
 
Example:
Sample : Who is Involved                                   Sample : Mid-level managers in IT
Phenomenon of Interest : What's Studied        Phenomenon of Interest : Impact of remote work on productivity
Design : How the Study is Conducted                Design : Case Study       
Evaluation : How Outcomes are Assessed        Evaluation : Measuring productivity through KPIs
Research Type : Nature of the Study                 Research Type : Exploratory Study
Elements in SLR Methodology
Search Strategy
The search strategy is the systematic plan for identifying relevant literature. It outlines where and how researcher will search for articles and other research materials, including the selection of databases, keywords, and search strings. A well-designed search strategy ensures comprehensive coverage and minimizes bias.
 
Inclusion & Exclusion Criteria
Inclusion and exclusion criteria are predetermined rules that define which studies will be included in the review and which will be excluded. These criteria consider factors such as study design, publication date, population, interventions, outcomes, and relevance to the research question.
 
Study selection process
This outlines the process of screening and selecting studies based on the inclusion and exclusion criteria. It typically involves multiple reviewers independently assessing the eligibility of each study, followed by a consensus process to resolve any disagreements.
 
Data Extraction
Data extraction involves systematically gathering relevant information from selected studies. This can include details about study characteristics, sample size, methodology, results, and other data necessary for addressing the research question. Data extraction forms or templates are often used to maintain consistency.
 
The elements in a Systematic Literature Review (SLR) methodology are crucial components that guide the systematic and structured process of conducting a review. Each element serves a specific purpose in ensuring the quality, transparency, and reliability of the review.
 
Quality Assessment
Quality assessment involves evaluating the methodological quality and risk of bias in the included studies. This step helps reviewers determine the reliability and validity of the evidence. Different tools or checklists may be used for quality assessment, depending on the type of studies included.
 
Data Synthesis
Data synthesis is the process of integrating and analyzing the data from the selected studies. It may include statistical techniques, thematic analysis, or other methods to draw meaningful conclusions, identify patterns, or explore variations in the evidence. The approach to data synthesis depends on the nature of the research question.
 
Reporting Standards
Reporting standards dictate how the findings of the review should be reported. These standards ensure transparency, replicability, and clear communication of the review methods and results. Commonly used reporting standards include PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) for systematic reviews and meta-analyses.
Why Scopus and Web of Science?
Scopus and Web of Science are two widely used academic databases, each with its strengths that make them valuable for rigorous searching, effective search string development, and quality control in the context of conducting a Systematic Literature Review (SLR) or any research endeavor.
 
Rigorous Searching
  • Allow for comprehensive searches, enabling you to cast a wide net.
  • Both Scopus and Web of Science offer extensive coverage of academic literature across various disciplines. They index a vast number of journals, conference proceedings, and other scholarly publications. This broad coverage helps ensure that you access a wide range of relevant studies during your search.
Effective Search String
  • Provide the tools needed to create and execute effective search strings.
  • Scopus and Web of Science provide advanced search capabilities, including Boolean operators, truncation, proximity searching, and field-specific searching. This allows you to develop complex and precise search strings to capture relevant studies and exclude irrelevant ones. The advanced search functionality is crucial for developing effective search strategies in an SLR.
Quality Control
  • Only indexed journals are included in these databases, ensuring a certain level of quality.
  • Both databases have quality control measures in place to ensure the accuracy and reliability of the indexed content. They often include peer-reviewed journals and high-impact publications, reducing the risk of including low-quality or unreliable sources in your review.
How Many and What Types of Databases for SLR?
The number and types of databases to be used in a Systematic Literature Review (SLR) depend on the research question, the topic of interest, and the field of study. The goal is to ensure a comprehensive and systematic search for relevant literature.
 
How Many Databases?
  • No complete database. So they suggest to use more than one database (Xiao & Watson, 2019).
  • Using more than one database, they will cover each other weaknesses (Younger, 2010).
What Types Of Databases?
  • Any database can be classified as a systematic literature review if it undergoes a rigorous process, regardless of its type.
  • It is recommended to consult the following two databases: SCOPUS and Web of Science.
How Many Articles Used in SLR?
The number of articles used in a Systematic Literature Review (SLR) can vary widely and is not fixed. The quantity of articles included in an SLR depends on several factors, including the research question, the scope of the review, the availability of relevant literature, and the specific criteria set for study inclusion.
  • The number of articles required for an SLR is not fixed; instead, it entirely relies on the systematic review process, including identification, screening, and eligibility.
  • It's important to remember that the primary goal of an SLR is not to maximize the number of included articles but to provide a comprehensive and unbiased summary of the available evidence that directly addresses the research question. The quality, relevance, and methodological rigor of the included studies are more critical than the sheer quantity. Reviewers should aim for a balance between comprehensiveness and quality in selecting the articles to be included.

 
Purpose of SLR Guidelines
The purpose of Systematic Literature Review (SLR) guidelines is to provide a structured framework for conducting, reporting, and evaluating systematic reviews in a rigorous and transparent manner. These guidelines serve several important purposes:
  • Serve as a roadmap for precision, rigor, and transparency in SLRs.
  • Maintain methodological consistency throughout the review process.
  • Ensure quality assurance and produce high-quality, reliable SLRs.
  • Facilitate clear and accurate communication of findings to the scientific community.
Review Protocol in SLRs
A Review Protocol is a detailed and structured plan that outlines the entire process of conducting an SLR. It serves as a foundation of a well-constructed building in the world of Systematic Literature Reviews (SLRs). Review Protocal is essential for understanding its role and significance.
 
What Is a Review Protocol?
It is a detailed and structured plan outlining the entire SLR process.
 
Purpose of a Review Protocol:
  • Structured Approach: Outlines research questions, objectives, methods, and review criteria.
  • Transparency: Makes the review process clear and understandable to others.
  • Reproducibility: Allows other researchers to replicate the study, ensuring result reliability.
  • Bias Avoidance: Minimizes bias through specified inclusion/exclusion criteria, search strategies, and data extraction methods.
 
Prominent Review Protocols: Examples include Cochrane, Campbell, ROSES, and Joanna Briggs.
Differences of Review Protocol
Review protocols play a significant role in various types of research, and there are differences in how they are structured and their specific purposes depending on the type of review being conducted:
 
Cochrane
Emphasizes evidence-based medicine and provides comprehensive guidelines for conducting reviews in the medical field.
 
Campbell
Focuses on systematic reviews in the social and behavioral sciences.
 
ROSES
Aims to improve the reproducibility of systematic reviews across various fields. It focuses on methods and transparency.
 
Joanna Briggs
Specializes in evidence-based healthcare and nursing. It offers a unique approach to systematic reviews, including its own methodologies and tools.
What is Publication Standard
Publication Standards are established guidelines or frameworks designed to ensure the transparent and rigorous reporting of systematic reviews and meta-analyses.
 
Publication standards in the context of Systematic Literature Reviews (SLRs) refer to guidelines and recommendations for reporting the results of an SLR in a clear, transparent, and standardized manner. These standards are crucial to ensure that the process and findings of an SLR are communicated effectively to the research community and readers.

Key elements of publication standards in SLRs include:
 
Transparency
  • SLR publication standards emphasize the importance of transparency in reporting the entire review process, from search strategies to data extraction, quality assessment, and data synthesis.
  • This transparency enables readers to understand how the review was conducted and the criteria used to include or exclude studies.
Reproducibility
  • Publication standards guide authors in providing sufficient detail in their reports so that other researchers can replicate the review process and confirm the results.
  • Reproducibility is a fundamental aspect of scientific research, and it ensures the credibility and reliability of the SLR.
Differences of Publication Standard
Publication standards for Systematic Literature Reviews (SLRs) provide guidelines for reporting the results of an SLR in a clear, transparent, and standardized manner. While the core principles of publication standards are generally consistent across different fields, there may be variations in specific guidelines and standards.
 
PRISMA 
Focuses on the comprehensive reporting of systematic reviews and meta-analyses, ensuring transparency and clarity.
 
RAMESES
Specializes in the clear and structured reporting of qualitative and mixed-methods reviews, with a focus on realist synthesis and meta-narrative approaches.
 
ROSES
ROSES encompasses areas such as research question formulation, search strategy, data extraction, risk of bias assessment, statistical analysis, and interpretation of results.
Common Databases in SLR
An abundance of scholarly articles, journals, and conference proceedings can be found within databases. Researchers will use these databases to search for relevant studies, which is the first and most important step in any SLR process.
 
  1. Scopus: Scopus is a comprehensive interdisciplinary database known for its extensive coverage of scientific literature.
  2. Web of Science: Web of Science is a widely respected database that includes a vast collection of scholarly articles and conference proceedings, making it an essential resource for SLR researchers.
  3. PubMed: PubMed is a go-to database for biomedical and life sciences literature. Researchers in fields like medicine and biology often rely on it for SLR.
  4. Science Direct: ScienceDirect stands as a reliable source for researchers spanning various fields.
  5. Google Scholar: Grants access to a wide range of sources, including both peer-reviewed and non-peer-reviewed materials, broadening the spectrum of information accessible for SLRs.
  6. Other Databases: There are many others designed for specialized fields and niches.
Database Selection Considerations
Selecting the right databases for the Systematic Literature Review (SLR) is a crucial step in the process. The choice of databases can significantly impact the comprehensiveness and relevance of the search results.
  1. Research Focus: Several databases are designed for specific academic disciplines, so it's important to make a thoughtful choice based on your research needs.
  2. Database Features: Certain databases may provide advanced search features and citation tracking, which can improve the efficiency of your research.
  3. Database Access: Some database may require institutional subscriptions or access through academic libraries.
Understanding Primary and Secondary Sources in SLR
Primary sources, also known as original sources, are the direct and unmediated evidence or information that is generated as a result of original research or observations. Secondary sources, on the other hand, are documents or publications that are based on, interpret, or analyze primary sources. They do not present original research but rather provide summaries, interpretations, or reviews of primary source materials.
 
Primary Sources: 
  • Primary sources encompass authentic works generated by researchers or authorities within a particular domain. This category comprises research papers, clinical experiments, case analyses, and firsthand information acquired via surveys, experiments, or direct observations.
  • The main goal is to find and assess primary sources, primarily by searching databases for original research articles and related studies
Secondary Sources:
  • Secondary sources encompass interpretations, summaries, or evaluations of primary source materials. This category includes literature reviews, meta-analyses, systematic reviews, and textbooks.
  • Secondary sources offer context, frame research questions, pinpoint knowledge gaps, and provide a broader understanding of a research area.
Useful Link & Resources
Reference to Useful Link & Resources

Haddaway, N. R., Collins, A. M., Coughlin, D., & Kirk, S. (2015). The role of Google Scholar in evidence reviews and its applicability to grey literature searching. PLoS ONE, 10(9), 1–17. https://doi.org/10.1371/journal.pone.0138237

Hayrol Azril Mohamed Shaffril, Asnarulkhadi Abu Samah, Samsul Farid Samsuddin, & Zuraina Ali. (201 9). Mirror-mirror on the wall, what climate change adaptation strategies are practiced by the Asian’s fishermen of all? Journal of Cleaner Production, 232, 104–117.

Hong, Q. N., Fàbregues, S., Bartlett, G., Boardman, F., Cargo, M., Dagenais, P., Gagnon, M. P., Griffiths, F., Nicolau, B., O’Cathain, A., Rousseau, M. C., Vedel, I., & Pluye, P. (2018). The Mixed Methods Appraisal Tool (MMAT) version 2018 for information professionals and researchers. Education for Information, 34(4), 285–291. https://doi.org/10.3233/EFI-180221

Lockwood, C., Munn, Z., & Porritt, K. (2015). Qualitative research synthesis: Methodological guidance for systematic reviewers utilizing meta-aggregation. International Journal of Evidence-Based Healthcare, 13, 179–187. https://doi.org/10.1097/XEB.0000000000000062

Moher, D., Liberati, A., Tetzlaff, J., & Altman, D. G. (2009). Preferred reporting items for systematic reviews and meta-analyses: The PRISMA statement. PLoS Medicine, 6(7), 1–6. https://doi.org/10.1371/journal.pmed.1000097

Wong, G., Greenhalgh, T., Westhorp, G., Buckingham, J., & Pawson, R. (2013). RAMESES publication standards: Meta-narrative reviews. BMC Medicine, 11(20), 1–15.

Xiao, Y., & Watson, M. (2019). Guidance on conducting a systematic literature review. Journal of Planning Education and Research, 39(1), 93–112. https://doi.org/10.1177/0739456X17723971


 
Reference to SLR Papers
Abrizah, A., Samaila, I. and Afiqah-Izzati, A. 2016. Systematic Literature Review Informing LIS Professionals on Embedding Librarianship Roles. Journal of Academic Librarianship. Vol. 42, no 6: 636-643

Alsolai, H., & Roper, M. (2020). A systematic literature review of machine learning techniques for software maintainability prediction. Information and Software Technology, 119(May 2019), 106214. https://doi.org/10.1016/j.infsof.2019.106214

Joshua Sani Magoi, M.K. Yanti Idaya Aspura and A. Abrizah. 2019. Social media engagement in developing countries: A boon or bane for academic libraries? Information Development. Vol. 35, no. 3: 374-387.

Noor Azizi, N. A., & Kaur, K. (2023). Indicators for Modernising the LIS Internship: Evidences from a systematic literature review. Journal of Librarianship and Information Science, 0(0). https://doi.org/10.1177/09610006231154536

Shaffril, H. A. M., Samah, A. A., & Kamarudin, S. (2021). Speaking of the devil: a systematic literature review on community preparedness for earthquakes. Natural Hazards, 0123456789. https://doi.org/10.1007/s11069-021-04797-4