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Systematic Literature Review, Meta Analysis and PRISMA 2020 Statement || Bibliometric Analysis thumbnail

Systematic Literature Review, Meta Analysis and PRISMA 2020 Statement || Bibliometric Analysis

eSupport for Research·
5 min read

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TL;DR

Start with a focused, specific, feasible research question before collecting any studies, because it drives eligibility and analysis choices.

Briefing

Meta-analysis and systematic literature review (SLR) are presented as the backbone for turning scattered research into a structured, evidence-based answer—then quantifying (meta-analysis) and reporting it transparently using PRISMA 2020. The core message is practical: build a repeatable pipeline from a clearly defined research question, through disciplined study selection and data preparation, to analysis (including moderator checks), and finally to reporting that lets others verify what was included and why. That matters because it reduces subjectivity in literature synthesis and makes future research directions easier to justify.

The discussion starts by separating SLR from meta-analysis. SLR is framed as a qualitative synthesis that provides a comprehensive picture of what is known and where future research should go. Meta-analysis adds quantification—turning results across studies into a statistical relationship—so researchers can test patterns more rigorously. The transcript also highlights why systematic methods matter: selection and interpretation can otherwise become subjective, and important evidence may remain hidden if only published studies are considered. Alongside that, it notes that systematic reviews can include unpublished or hard-to-find studies when feasible, and that the process typically begins with a research question and ends with a structured report.

A step-by-step workflow is then laid out for both SLR and meta-analysis. For SLR, the sequence runs from defining the research question, collecting and preparing data, analyzing it, and reporting findings. The review can be domain-based, theory-based, or method-based depending on the goal. For meta-analysis, the workflow mirrors the same backbone but adds statistical decisions: define the research question, collect studies, apply inclusion/exclusion criteria, clean and prepare the dataset, and then choose an appropriate model for effect estimation. The transcript specifically mentions fixed-effect and random-effects models, and it emphasizes testing beyond a single pooled estimate through moderator analysis.

Moderator analysis is described as a way to examine when and why effects differ across studies. Techniques named include subgroup analysis, meta regression, and multilevel analysis—used to test how moderators influence the meta-analytic relationships. The transcript also points to tools and software commonly used for meta-analysis workflows, including R and R packages, and it references visualization approaches such as word clustering and mapping views (with a “VOSviewer” mention) to interpret research themes and connected terms.

Finally, PRISMA 2020 is introduced as the reporting standard for systematic reviews and meta-analyses. The emphasis is on a checklist and a flow diagram that document the full journey of studies: identification (from databases/registers), screening, eligibility assessment, and inclusion. The transcript notes that PRISMA 2020 was published in 2009 and later updated, and it stresses that the checklist’s structure—title, abstract, methods (eligibility criteria and data collection), results, discussion, and other information—helps ensure completeness and transparency. A PRISMA flow example is described with numbers moving from initial records through exclusions to the final included studies, reinforcing that reviewers must record reasons for exclusions and keep the selection process auditable. The overall takeaway is that combining SLR/meta-analysis methods with PRISMA 2020 reporting creates a defensible, reproducible literature synthesis that supports credible future research directions.

Cornell Notes

The transcript lays out a practical blueprint for conducting a Systematic Literature Review (SLR) and then extending it into a meta-analysis, with PRISMA 2020 used to report the work transparently. It distinguishes SLR’s qualitative synthesis—mapping what is known and proposing future directions—from meta-analysis’s quantification across studies using statistical models. The workflow includes defining a focused, feasible research question; collecting studies; applying inclusion/exclusion criteria; preparing and cleaning data; selecting fixed-effect or random-effects models; and running moderator analyses such as subgroup analysis, meta regression, and multilevel analysis. PRISMA 2020 then standardizes reporting through a checklist and a flow diagram that tracks identification, screening, eligibility, and inclusion, including reasons for exclusions. This combination reduces subjectivity and makes results verifiable and easier to build upon.

What’s the practical difference between an SLR and a meta-analysis?

An SLR is used to build a comprehensive, structured picture of what is known and where future research should go, often relying on qualitative synthesis. A meta-analysis adds quantification by combining results across studies to estimate relationships statistically. The transcript frames SLR as the foundation for identifying themes and directions, while meta-analysis provides pooled evidence and tests patterns more rigorously.

Why does the workflow emphasize inclusion/exclusion criteria and data preparation?

Systematic selection is meant to limit subjective choices. After defining the research question, the process requires searching databases/registers, then applying eligibility rules to decide which studies to keep and which to exclude. Data preparation includes cleaning and handling unwanted records (such as irrelevant publication types or out-of-scope topics), and it also flags issues like publication bias as something reviewers should consider.

How do fixed-effect and random-effects models fit into meta-analysis?

Once studies are selected and data are prepared, meta-analysis requires choosing an effect estimation model. The transcript names fixed-effect and random-effects models as options, implying different assumptions about whether study effects are consistent or vary across studies. The chosen model then supports the overall pooled analysis and downstream moderator testing.

What is moderator analysis, and which methods are mentioned?

Moderator analysis checks whether the main effect changes depending on study characteristics. The transcript lists subgroup analysis, meta regression, and multilevel analysis as approaches to test how moderators influence the meta-analytic relationship. This helps explain heterogeneity—why results differ across studies rather than treating them as identical.

What does PRISMA 2020 add to the process?

PRISMA 2020 standardizes reporting so others can audit the review. It includes a checklist (with structured sections like title, abstract, methods, results, discussion, and other information) and a flow diagram that tracks records from identification through screening, eligibility, and inclusion. The flow diagram also records exclusion reasons, making the selection process transparent.

How can visualization tools support interpretation in literature synthesis?

Beyond statistical pooling, the transcript mentions using mapping/visualization approaches such as VOSviewer for generating word clusters and relationship maps (e.g., connected terms and themes). These visuals can make it easier to interpret research streams and formulate future research questions based on how topics and keywords relate.

Review Questions

  1. What steps must be completed before choosing a fixed-effect versus random-effects model in a meta-analysis?
  2. How does PRISMA 2020’s flow diagram improve transparency compared with a narrative description of study selection?
  3. Which moderator-analysis methods would be most appropriate if you suspect effects differ by study characteristics, and why?

Key Points

  1. 1

    Start with a focused, specific, feasible research question before collecting any studies, because it drives eligibility and analysis choices.

  2. 2

    Use SLR to build a comprehensive understanding of what is known and to define future research directions, then use meta-analysis to quantify relationships across studies.

  3. 3

    Apply explicit inclusion/exclusion criteria and document reasons for exclusions to reduce subjectivity and improve auditability.

  4. 4

    Prepare and clean the dataset before analysis, including handling irrelevant publication types and considering issues like publication bias.

  5. 5

    Choose an appropriate meta-analysis model (fixed-effect or random-effects) and then test heterogeneity using moderator analysis.

  6. 6

    Use moderator tools such as subgroup analysis, meta regression, and multilevel analysis to explain when and why effects differ.

  7. 7

    Report the review using PRISMA 2020’s checklist and flow diagram so identification, screening, eligibility, and inclusion are fully traceable.

Highlights

Meta-analysis is positioned as the quantification layer added on top of an SLR’s structured synthesis of what is known.
Moderator analysis is treated as essential for explaining heterogeneity, with subgroup analysis, meta regression, and multilevel analysis named as key methods.
PRISMA 2020 is presented as the transparency mechanism: a checklist plus a flow diagram that tracks records from identification to final inclusion with exclusion reasons.

Topics

Mentioned

  • SLR
  • PRISMA
  • VOSviewer