A systematic literature review (SLR) is a methodical and complete approach of identifying, evaluating, and synthesizing offered research on a specific topic or research question. It identifies, estimates, and synthesizes existing research material on a specific topic or research question.
SLR differs from usual literature reviews, which are often more narrative and subjective, because SLRs are structured processes with the objective of minimizing bias and requiring a clear and replicable summary of the available evidence.
Purpose of Systematic Literature Reviews
Systematic literature reviews serve several necessary purposes in research:
Inform practice and policy
SLRs create an evidence-based basis necessary to make informed decisions in practice, policy, and research; creating findings from more than one study gives consistent conclusions that drive assumed actions and involvements.
Identifying Research Gaps
SLRs, through a comprehensive review of the literature, show areas where research is inadequate, managing further studies and determining that researchers focus on the questions which are not answered or even developing issues.
Establishment of Research Consensus
SLRs will help to determine a consensus on areas where the findings of research may be conflicting or inconsistent. The systematic review and synthesis of available evidence provided by SLRs emphasize what is known and where there is consensus.
More Transparency and Replicability
The organized nature of SLRs involves the detailed description of methods and processes, hence giving more transparency and allowing for more replicability, thereby adding more credibility and consistency to the research.
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Why Systematic Literature Reviews?
Systematic literature reviews are essential for numerous reasons:
Evidence-Based Practice:
SLRs are one of the foundations of evidence-based practice. It is a complete, yet balanced, summary of available research to inform policy, practice, and research decisions.
Comprehensive Overview:
Through supervising a systematic search and analysis of all relevant studies on a particular question, SLRs provide an overview of the current state of knowledge, including consistent findings, drifts, and gaps in the available research.
Minimizing Bias:
The structured nature of SLRs reduces the prospect of bias. It prevents personal subjective preference on the part of the researcher or careful reporting of results from being factored into the review.
Duplication and Transparency:
The process for the SLR is documented in detail, other researchers can replicate the review. This improves precision and enhances the integrity of the findings.
Identification of Research Gaps:
Through examining various studies in wide circles, SLRs are capable of highlighting where a literature gap exists that needs to be filled by extreme research and, hence, indicating the line of future studies and helping to add to knowledge.
Systematic Literature Review in Research
A systematic literature review signifies a clearly specified, thorough process in the gathering, analyzing, and synthesizing of research indication material on a certain topic. The following five major steps of an SLR are dealt with in this subsection:
Formulation of the Research Question
First, in the steps of an SLR, the research question must be identified in as concise and clear a form as possible. It should be specific, accessible, and relevant for the field under study.
Eligibility criteria
The researcher sets addition and exclusion criteria to identify the types of studies included or prevented from the review.
Comprehensive search plan
There is an extensive search conducted via many records and sources to track every relevant study. This search plan is usually well-documented, where a complete presentation of words used for the search, list of databases accessed, and the number of recovered studies is provided.
Study Selection
The identified studies are then projected for inclusion and exclusion criteria, often successively, to select only highly relevant and good-quality studies for the review.
Data Extraction
Consistent data extraction is carried out from the selected studies, many times using predeveloped forms. The extracted data can include characteristics of the study, results, and potential biases.
Quality Assessment
The process involves the assessment of quality for the included studies, often using standardized tools or specifications. This helps to establish the degree of reliability and validity of the findings.
Data Synthesis
Qualitative or quantitative data synthesis-for instance, meta-analysis-provides a summary of evidence. It is at this stage that such syntheses should provide an answer to the original research question and highlight key findings.
Results are reported
Findings of the SLR are presented in a tabulated form and usually presented based on guidelines like PRISMA – Preferred Reporting Items for Systematic Reviews and Meta-Analyses.
Systematic Literature Review Example
Now, let’s see an example of a systematic literature review for the field of education:
- Topic: Effectiveness of reversed classroom models at the higher education level.
- Research Question: How do flipped classroom models improve learning outcomes for students in higher education?
Steps:
- Inclusion Criteria: A study that evaluates the effectiveness of flipped classroom models in a higher education setup, in peer-reviewed journals, and written in English.
- Search Strategy: Use internet sources such as ERIC, PubMed, and Google Scholar were searched using terms such as “flipped classroom,” “higher education,” and “student learning outcomes.”
- Study Selection: From an initial 500 identified studies through searching, 30 were identified to be relevant and of high quality.
- Data Extraction: Extracted data included key study design information, sample size, details about intervention, and measures of outcome.
- Quality Assessment: All studies were assessed for bias. In the synthesis, more importance is given to high-quality studies.
- Synthesis of Data: The review finds that flipped classroom models appear to generally be associated with improved student engagement and enhanced learning outcomes, even though results vary across disciplines and based on quality of implementation.
The above example has highlighted how SLRs provide a systematic and visible approach to synthesizing research evidence.
Systematic Literature Review vs. Literature Review
While both systematic literature reviews and traditional literature reviews involve reviewing existing research, they differ in several keyways:
Structure and Process:
- Systematic Literature Review: A predefined, structured process is followed, with explicit inclusion criteria for studies, an extensive search strategy adopted, and data synthesized thoroughly.
- Literature Review: It can be more narrative, less structured, and is often subjective, as the reviewer expresses his or her perception of the literature. It may not entail a comprehensive search or explicit inclusion criteria.
Scope:
- Systematic Literature Review: Includes a directed research question or topic of interest that the review expects to cover all available studies on.
- Literature Review: Sometimes may be more general, covering broader areas, topics, or theories, and is often used to provide an overview rather than in-depth analysis.
Outcome:
- Systematic Literature Review: Summary of research is clear and evidence-based; may enable practice or policy insights.
- Literature Review: The literature is synthesized and, in many cases, provides background information or context of the research study being controlled.
Decrease of Biases:
- Systematic Literature Review: Places a greater emphasis on reduced bias as it ensures the process is transparent and replicable.
- Literature Review: Less likely to be visible in the processes carried out and therefore has a higher chance of introducing biases.
Systematic Literature Review Methodology
The methodology of a systematic literature review is step-by-step, planned, and developed in such a way that any possible biases are minimized while examining the literature. An overview of the methodology includes:
1. Planning the Review:
- Research Question: Clearly define a research question or objective.
- Development of Protocol: Develop a protocol outlining, among others, the strategy for the search of publications, inclusion/elimination criteria, and methods for data extraction and synthesis.
2. Conducting the Review:
- Search Strategy: They need vast research across various databases to identify studies. Besides, the very search should be verified in as much detail as possible.
- Study Screening: Studies must be screened against some determined set of criteria to ensure that they meet the criteria for inclusion. This is often a multistep process.
- Data Extraction: Data from the included studies should be separated using standardized forms or tools. This data may come in terms of study design, outcomes, and sources of potential bias.
3.Synthesizing the Data:
- Qualitative Synthesis: Summarize the results of included studies, highlighting common themes, trends, and areas of merging and divergence.
- Quantitative Synthesis (Meta-Analysis): Where possible, statistical methods may be used to combine results across studies to provide an estimate of effect size that is more precise than that from individual studies.
4. Reporting the Results:
- Structured Report: Report findings in a structured manner, usually informed by the PRISMA checklist. This should include a reported research question, materials and methods, results, discussion, and conclusions.
- Transparency: The review should be clear and reproducible, with well-documented methods.
5. Updating the Review:
- Continuous Review: Systematic reviews need to be updated now and then to keep up with new research that keeps the findings current and relevant.
Tips for Conducting a Systematic Literature Review
- Precision of the Research Question: The research question must be focused, measurable, and relevant. A clear and well-defined question will enable one to move forward with reviewing.
- Development of a Protocol: There should be a review protocol that outlines your process of reviewing, including your search strategies, inclusion and exclusion criteria, and methods of data extraction and synthesis.
- Several Databases: Searches should be carried out in several databases for completeness of review. Dependence on one source of literature will not provide comprehensive information.
- Data Extraction: Data is extracted systematically using standardized forms or tools to make the process consistent and as free of bias as possible.
Drawbacks of Systematic Literature Reviews
Despite their many benefits, systematic literature reviews also have some drawbacks:
- Time-consuming: SLRs take several months and sometimes even years to complete.
- Resources: SLRs are resource-intensive in that they require multi-database access, software management references, and sometimes a group of researchers.
- Complexity: The execution of an SLR involves complex processes in expertise methodology, data extraction, and synthesis that may act as a barrier to new, inexperienced researchers.
- Potential for Bias: Even while attempts are made to minimize it, study selection and data interpretation tend to affect the SLR.
- Limited Scope: Because of the nature of this SLR method, an SLR covers research concerning a very specific research question and thus probably cannot give an overview of a greater topic.
- Publication Bias: SLRs can again be caught in the web of publication bias, where only positive or significant results are published, thus providing an incomplete picture of evidence.
Final Thoughts
Systematic reviews are powerful tools that synthesize research evidence in a way that is systematic, transparent, and balanced. They are important in informing practice, identifying gaps in research, and providing consensus on subject matters within different fields. The following blog gives an overview of systematic literature reviews, furnishing the readers with some practical tips on how to conduct them while considering some disadvantages.
