Mapping the Unknown: 4 Key Steps in Planning a Scoping Review
A friendly roadmap for newbie researchers
To know (zhi) what you know and know what you do not know—this then is wisdom.
— Confucius, The Analects
To me, nothing can better capture the essence of what scoping reviews aim to accomplish in research—map what is known and identify what remains unexplored—than this ancient wisdom from Confucius.
A popular knowledge synthesis approach in health and social science disciplines, scoping reviews serve as the magnifying glass that brings clarity to complex research questions. Yet many graduate students and early-career researchers find themselves lost in the process—struggling with too broad questions, narrow eligibility criteria, or weak search strategies.
How can we better prepare for an effective scoping review—the one that leads to findings that enrich our understanding and open new paths on the research agenda? That’s what I aim for in the coming Research Log series on scoping reviews: condense the recommendations from a collection of papers on good practices in conducting this knowledge synthesis approach.
For this week's issue, I want to step back with a loupe in hand to uncover:
What are scoping reviews designed to do and not do?
What are the essential steps to prepare for an effective scoping review?
So, let's dive in!
Scoping Reviews: A Brief Introduction
Think of scoping reviews as an exploration of uncharted land. They help map established knowledge, existing research paths, promising unexplored regions, and potential hazards such as contradictory findings or methodological challenges.
Though the scoping review approach can be mistaken for its sibling, the systematic review, due to their similarity in methodological principles, these two approaches serve different purposes. While systematic reviews seek to synthesize findings from the highest quality studies, scoping reviews aim to identify the breadth of available research. Since choosing the right approach to knowledge synthesis determines the success of the endeavor, let’s start the journey by learning what scoping reviews are designed to do and not to do.
Scoping reviews are designed to:
Map existing literature on a particular topic: When charting a research topic, scoping reviews help identify key concepts and theories, map the volume of evidence, categorize sources, and set the boundaries between the known and the unknown.
Clarify concepts: When concepts in a field are unclear or inconsistently applied, scoping reviews can help establish definitions and boundaries.
Inform research priorities: Before committing resources to a full systematic review or primary research, a scoping review can identify gaps and opportunities in the existing literature.
Provide context: When background information is needed to understand a phenomenon, scoping reviews offer a panoramic view of the available evidence.
They are not intended to:
Provide recommendations for practice
Inform clinical guidelines
In other words, if you’re trying to understand "what's out there," a scoping review is appropriate. But if you want to know "what works," you’d better use other types of literature reviews. For fundamental types of literature reviews in health sciences, check out my Research Log issue on the 6-phase approach to choose the right type of literature review.
4 Key Steps in Planning a Scoping Review
Before diving into the exhaustive searches for evidence, you need to develop an a priori protocol—your research guideline.
This document provides a roadmap for the whole scoping review process. It helps formulate a clear research question, establish well-balanced eligibility criteria, develop relevant search strategies, and plan for data extraction, evidence analysis, and result presentation.
A protocol is also a project management tool that keeps you focused on the review objective. Whether reviewing literature alone or with a team, it minimizes ad hoc decision-making that might compromise the quality of your review.
Drawn from the protocol framework proposed by the Joanna Briggs Institute (JBI) - "the most rigorous and defined methodology" for scoping reviews, the following steps will help you navigate the scoping review process with clarity and confidence.
1. Defining a Review Question
You cannot reach the destination if you don't know where you're headed.
Likewise, you cannot conduct an effective scoping review without a well-defined research question. The clearer the question, the more efficiently you can navigate the review process and identify relevant findings. Like a compass, a precise review question ensures that your literature search remains focused, and your synthesis of evidence directly addresses your research objectives.
Use the "PCC" mnemonic to formulate your scoping review question:
Population: Who is the review focusing on?
Concept: What is being examined?
Context: What are the relevant settings or factors?
For example, if you want to understand what is known about the well-being among people aged 65 and over who live in bereavement, your Population will be "older adults aged 65 and over," your Concept "well-being," and your Context "living in bereavement." Your review question could be: What influences the well-being of older adults aged 65 and over who live in bereavement?
In short, this PCC approach ensures your review maintains focus and relevance.
2. Balancing Eligibility Criteria
Have you ever identified too many papers to review? Or conversely, found only a handful?
That may stem from unbalanced eligibility criteria.
Eligibility criteria are the rules that determine which papers to include or exclude in your review. These criteria must align with your research question and be carefully balanced—if too broad, you risk being overwhelmed by volume; if too narrow, you might find insufficient literature to analyze.
When establishing your eligibility criteria, ask yourself:
- Do these criteria directly reflect my PCC elements?
- Will these criteria help me answer my research question?
- Are my inclusion timeframes appropriate for my topic? (For rapidly evolving fields, consider a narrower timeframe)
- Have I considered non-English literature if relevant to my topic?
- Am I including the right types of publications (peer-reviewed, gray literature, etc.)?
3. Developing a Comprehensive Search Strategy
Scoping reviews depend on a comprehensive search strategy to capture all available evidence related to the research topic.
Just as a wide net alone doesn’t guarantee a good catch, an efficient search strategy for scoping reviews requires both pertinent keywords and relevant databases.
The JBI manual recommends taking a 3-stage approach in developing the search strategy for scoping reviews:
Initial Search: Search for articles in at least two relevant databases to identify keywords in titles, abstracts, and indices of likely relevant papers.
Formal Search: Using identified terms, conduct comprehensive searches across selected databases. Document these searches for inclusion in your PRISMA flow chart.
Reference List Search: Examine reference lists of identified studies to locate additional relevant papers.
A practical tip: Consider working with a librarian specializing in your field. They can help you identify the most appropriate databases for your field and develop more sophisticated search strings that capture relevant literature while filtering out noise.
4. Planning for Data Extraction, Analysis, and Presentation
How will you extract data?
What analysis is the most appropriate to make sense of the evidence?
How can you ensure that the review's findings are presented clearly and coherently with the review's objective?
These are some questions you can ponder when developing the protocol for your scoping review.
Recommendations & Cautions for a Rigorous and Transparent Scoping Review
For data extraction, it is recommended to:
Develop a standardized extraction form
Pilot test the form across several papers to ensure consistency
Document all changes in the charting table in the final review
For data analysis, be cautious with thematic analysis. Though this analysis approach is reported in numerous scoping reviews, the JBI approach, the most rigorous scoping review methodology, finds it surpasses the purpose and scope of scoping reviews.
For the result presentation, it is recommended to use tables and charts, accompanied by a narrative summary to connect the results to the reviews' objectives.
Tools and Resources to Assist Beginners
These two tools can support your scoping review journey:
JBI Manual for Evidence Synthesis (Chapter 10): Comprehensive guidance on conducting scoping reviews
PRISMA-ScR: Reporting guidelines for scoping reviews (used in conjunction with JBI guidance)
Additional practical resources:
- Covidence: A web-based tool to help manage your review process
- Rayyan: Free web application for screening and selecting studies
Charting Your Research Journey: The Power of Scoping Reviews
Conducting a scoping review is much like exploring uncharted territory—it requires careful planning, methodical execution, and transparent reporting. The four steps we've outlined—defining your question, balancing eligibility criteria, developing a comprehensive search strategy, and planning for data extraction and presentation—provide you with a reliable compass for this journey.
Remember that scoping reviews serve specific purposes that distinguish them from other review types:
- They map the landscape of available evidence
- They clarify concepts that may be inconsistently applied
- They identify gaps worthy of further exploration
- They provide the context needed to understand complex phenomena
By understanding these purposes and applying the methodological approaches we've discussed, you'll ensure your scoping review meets high standards of quality and usefulness. The knowledge map you create will not only inform your own research path but also guide others who follow in your footsteps.
Taking Your First Steps
If you're new to scoping reviews, rigorously use the JBI Manual and PRISMA-ScR checklist as your guidebooks, and don't hesitate to seek mentorship from experienced researchers.
Remember Confucius's wisdom about knowing what you know and knowing what you don't know. A well-executed scoping review brings you closer to that wisdom by illuminating both the known and unknown territories in your field.
What research question might you explore through a scoping review? The journey of a thousand miles begins with a single step—and in research, that step often starts with mapping what's already known.
References
Peters, M. D. J., Godfrey, C., McInerney, P., Munn, Z., Tricco, A. C., Khalil, H. (2020). Scoping Reviews. In Aromataris E, Lockwood C, Porritt K, Pilla B, Jordan Z, editors. JBI Manual for Evidence Synthesis. JBI; 2024. Available from: [https://synthesismanual.jbi.global]{.underline}. [https://doi.org/10.46658/JBIMES-24-09]{.underline}
Peters, M. D. J., Marnie, C., Tricco, A. C., Pollock, D., Munn, Z., Alexander, L., McInerney, P., Godfrey, C. M., & Khalil, H. (2020). Updated methodological guidance for the conduct of scoping reviews. JBI Evidence Synthesis, 18(10), 2119. https://doi.org/10.11124/JBIES-20-00167
Peters, M. D. J., Godfrey, C., McInerney, P., Khalil, H., Larsen, P., Marnie, C., Pollock, D., Tricco, A. C., & Munn, Z. (2022). Best practice guidance and reporting items for the development of scoping review protocols. JBI Evidence Synthesis, 20(4), 953. https://doi.org/10.11124/JBIES-21-00242
Pollock, D., Davies, E. L., Peters, M. D. J., Tricco, A. C., Alexander, L., McInerney, P., Godfrey, C. M., Khalil, H., & Munn, Z. (2021). Undertaking a scoping review: A practical guide for nursing and midwifery students, clinicians, researchers, and academics. Journal of Advanced Nursing, 77(4), 2102--2113. https://doi.org/10.1111/jan.14743
Tricco, A. C., Lillie, E., Zarin, W., O'Brien, K. K., Colquhoun, H., Levac, D., Moher, D., Peters, M. D. J., Horsley, T., Weeks, L., Hempel, S., Akl, E. A., Chang, C., McGowan, J., Stewart, L., Hartling, L., Aldcroft, A., Wilson, M. G., Garritty, C., ... Straus, S. E. (2018). PRISMA extension for scoping reviews (PRISMA-ScR): Checklist and explanation. Annals of Internal Medicine, 169(7), 467--473. https://doi.org/10.7326/M18-0850