What is a Systematic Review? Definition, Steps, and Examples

Systematic reviews have become a go-to tool for researchers, clinicians, and policymakers who want a clear, reliable picture of the evidence on a given topic.¹ Instead of skimming a few studies, systematic reviews dive deep, collecting and analyzing all relevant research to provide trustworthy insights. They are especially important in fields like healthcare and social sciences, where decisions need to be backed by solid, comprehensive evidence. 

In this article, we will walk through the step-by-step process of conducting a systematic review, explore the different types, and explain how they differ from meta-analyses. We will also highlight the key features that make a review truly systematic and show why following these steps is important for producing reliable, evidence-based conclusions. 

By the end, you will have a clear understanding of how systematic reviews are conducted, why they matter, and how they are used in research. Whether you are new to the topic or looking to refresh your knowledge, this guide provides practical insights to help you navigate and apply systematic reviews effectively. 

What is a Systematic Review?

A systematic review is a rigorous, step-by-step method for gathering, evaluating, and synthesizing all high-quality research on a focused question. Unlike a regular literature review, it considers all relevant studies, helping to reduce bias and provide a clear, reliable picture of the evidence. 

The process involves defining a clear question, conducting a thorough search, applying strict rules for which studies to include, assessing the quality of the research, and then summarizing the findings in an organized way.¹ By combining and analyzing data from multiple studies, systematic reviews provide trustworthy, evidence-based insights that guide clinical practice, policy, and research decisions. 

You Might Like Reading: What are the Types of Literature Reviews? 

Characteristics of a Systematic Review

A systematic review is not just a thorough literature search—it is a carefully planned, transparent, and reproducible process that turns scattered research into clear, trustworthy insights. Here’s what makes a systematic review tick: 

• A Clear Question – Everything starts with a focused research question, often framed with PICO (Population, Intervention, Comparator, Outcome) to guide the review.
• A Predefined Plan – A detailed protocol maps out every step in advance, ensuring a transparent and reproducible process.
• A Thorough Search – Multiple databases, grey literature, and reference lists are combed systematically to capture all relevant studies.
• Critical Quality Check – Each study is carefully assessed for validity and risk of bias, ensuring that no weak evidence distorts the conclusions.
• Organized Synthesis – Results are presented clearly, either as a narrative summary or a meta-analysis, making complex evidence easy to understand.
• Transparent Reporting – Following standards like PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses), all methods, decisions, and limitations are laid out openly.
• Teamwork Makes the Dream Work – Collaborating with content experts, methodologists, statisticians, and librarians ensures accuracy and depth.

In short, systematic reviews transform fragmented research into reliable, high-quality evidence that informs practice, policy, and future research. 

5 Types of Systematic Review

While there are many approaches within evidence synthesis, five core types commonly referenced in research methodology resources are described below. These differ in purpose, scope, rigor, and output, making them suitable for different research questions and decisionmaking needs.² 

Review Type	Purpose	Key Characteristics	Typical Outcomes	Examples
Traditional Systematic Review	To answer a narrowly focused research question with comprehensive, unbiased evidence.	Highly structured protocol; exhaustive search; formal critical appraisal; transparent methodology.	Detailed synthesis that supports evidencebased practice or policy.	Evaluate the effectiveness of a specific teaching method, like blended learning, by synthesizing all experimental studies in higher education.
Scoping Review	To map the breadth and nature of evidence on a topic without focusing on narrow questions.	Broad search strategy; exploratory; often does not include formal quality appraisal.	A landscape of research areas, themes, gaps, and concept definitions.	Map research on digital learning tools for university students, identifying what has been studied and where gaps exist.
Rapid Review	To provide timely evidence in urgent or policyrelevant contexts.	Follows systematic principles but streamlines or omits steps (e.g., limits search scope or appraisal depth).	Accelerated synthesis that may have less breadth or precision.	Quickly summarize evidence on interventions to improve student engagement during sudden shifts to online learning during COVID-19.
MetaAnalysis	To quantitatively combine results from multiple compatible studies.	Statistical pooling of effect sizes; nested within a systematic review.	Aggregate numerical estimates with increased statistical power.	Combine data from multiple studies to determine the overall impact of active learning strategies on student performance.
Umbrella Review	To synthesize evidence across several systematic reviews on related topics.	“Review of reviews”; highestlevel evidence perspective.	Summaries of previous reviews’ conclusions to inform broad decisionmaking.	Summarize several systematic reviews on approaches to improve academic retention in higher education, providing a high-level overview for policymakers or educators.

How to Write a Good Systematic Review?

Systematic review is not just about summarizing studies; it is about doing it rigorously, transparently, and in a way that other researchers could replicate.³ Here’s a step-by-step guide to make your review both authoritative and readable: 

1. Start with a Sharp Research Question. Do not wander. Use frameworks like PICO (Population, Intervention, Comparison, Outcome) to narrow your focus. A clear question is the backbone of a solid review.

2. Draft a Rock-Solid Protocol. Lay out your objectives, inclusion/exclusion rules, search strategy, and analysis plan. Additionally, register it on PROSPERO. It makes your work more transparent and credible.

3. Go All Out on Literature Search. Hit multiple databases: PubMed, Scopus, Web of Science, and do not forget gray literature. Use Boolean operators and MeSH (Medical Subject Headings) terms to make sure you catch everything relevant. Document every step so others can reproduce it.

4. Screen Like a Pro. Filter studies in two rounds: titles/abstracts first, then full texts. Stick to your criteria and track your process. A PRISMA diagram can help you visualize your journey from hundreds of papers to the final selection.

5. Check Study Quality. Do not treat all studies equally. Use tools like Cochrane Risk of Bias or Newcastle-Ottawa Scale to evaluate reliability. This helps you weigh evidence thoughtfully.

6. Extract Key Data Carefully. Collect the essentials: authors, sample size, interventions, outcomes, and results. Structured forms or software like Covidence make this smoother and reduce errors. Once extraction is complete, Paperpal can help you convert technical notes into well-structured academic writing without losing accuracy.

7. Synthesize and Analyze. Decide whether a narrative summary or a meta-analysis fits your data. Highlight patterns, contradictions, and trends. Weigh findings by study quality so readers know what’s solid and what’s tentative.

8. Write Clearly and Transparently. Follow PRISMA guidelines. Structure your review with clear sections: introduction, methods, results, discussion, conclusion, and appendices. Include search details so anyone could replicate your work. To make your systematic review easier to read and journal-ready use Paperpal to refine academic tone, improve clarity, and strengthen overall flow across sections.

9. Keep It Fresh. Science moves fast. Set up alerts or periodic reviews to update your systematic review. Fresh evidence keeps it relevant and influential.

With these steps, your systematic review will not just summarize research, it will guide practice, inform policy, and shine a light on gaps waiting for new discoveries. 

Examples of Systematic Review

Given below are examples showing how a systematic review can be applied in education research. 

Example 1: Evaluating Online Learning Effectiveness in Higher Education 

• Background: Online learning has become increasingly common in universities, especially after rapid digital transformation. Many studies have explored its impact on student performance, engagement, and satisfaction, but results vary widely.

• Systematic Review Process:
  • Defining the Question – What impact does online learning have on academic performance and student engagement in higher education?
  • Searching the Literature – Conduct comprehensive searches across multiple academic databases using predefined keywords and inclusion criteria.
  • Screening Studies – Independently review titles, abstracts, and full texts to identify studies that meet eligibility requirements.
  • Quality Assessment – Evaluate the methodological quality of each study to understand strengths and potential biases.
  • Synthesizing Evidence – Summarize findings narratively by comparing patterns, trends, and differences across studies.

• Findings: The systematic review shows that online learning can be just as effective as face-to-face instruction when courses are well designed, though outcomes depend heavily on student support, course structure, and instructor engagement.

Example 2: Exploring the Effectiveness of Active Learning Strategies in Higher Education 

• Background: Active learning strategies, such as group discussions, flipped classrooms, and problem-solving activities are increasingly used in higher education to improve student understanding and engagement. Many studies have examined their impact, but findings differ across disciplines and course formats.

• Systematic Review Process:
  • Defining the Question – How do active learning strategies influence student learning outcomes in higher education?
  • Searching the Literature – Conduct structured searches across education and multidisciplinary databases using predefined keywords.
  • Screening Studies – Review titles, abstracts, and full texts to select studies that meet established inclusion criteria.
  • Quality Assessment – Evaluate study design, measurement tools, and potential sources of bias.
  • Synthesizing Findings – Summarize and compare results narratively to identify patterns, strengths, and limitations across studies.

• Findings: The systematic review indicates that active learning generally leads to improved understanding and engagement among higher education students, though the effectiveness depends on class size, discipline, and how well the activities are implemented.

Advantages and Disadvantages of Systematic Review

Advantages of Systematic Reviews 

• They provide a clear, big-picture view of what is already known about a topic by bringing together findings from many studies.
• The results are generally more reliable and less prone to bias because these reviews follow a structured and transparent process.
• Systematic reviews help researchers and policymakers make evidence-based decisions instead of relying on single studies.
• They can highlight gaps in the existing literature, pointing to areas where more research is needed.

Disadvantages of Systematic Reviews 

• They are time-consuming and often take months, or even years, to complete.
• The quality of the review depends heavily on the quality of the studies included; poor data means weaker conclusions.
• Developing and running a comprehensive search strategy can be complex and resource-intensive.
• If the available studies are very different from one another, drawing clear conclusions can be challenging.

Being mindful of both the advantages and disadvantages helps set realistic expectations and leads to better research decisions. While systematic reviews offer powerful, evidence-based insights, understanding their limitations ensures the findings are interpreted carefully and used in the right context. 

While the methodology takes time, Paperpal can help speed up the manuscript-writing phase with research-ready language and clarity improvements.

Key Takeaways

• A systematic review is a structured and transparent way to answer a focused research question by gathering all relevant evidence, rather than relying on a selective or narrative overview.
• It follows a predefined protocol, which helps ensure consistency, reduces bias, and makes the process reproducible.
• Systematic reviews are different from meta-analyses; while some include statistical pooling of results, many rely on careful qualitative synthesis instead.
• Having at least two independent reviewers is essential to improve reliability when selecting and assessing studies.
• A thorough search strategy, often covering multiple databases and grey literature, is key to capturing the full scope of existing research.
• Even when studies are too diverse to combine statistically, systematic reviews still provide valuable insights that support evidence-based decisions.

Frequently Asked Questions

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References 

1. Charrois, T. L. (2015). Systematic reviews: what do you need to know to get started?. The Canadian journal of hospital pharmacy, 68(2), 144.

2. Zaccagnini, M., & Li, J. (2023). How to conduct a systematic review and meta-analysis: a guide for clinicians. Respiratory Care, 68(9), 1295-1308.

3. Møller, A. M., & Myles, P. S. (2016). What makes a good systematic review and meta-analysis?. BJA: British Journal of Anaesthesia, 117(4), 428-430.