gap in the research literature

The Research Gap (Literature Gap)

I f you’re just starting out in research, chances are you’ve heard about the elusive research gap (also called a literature gap). In this post, we’ll explore the tricky topic of research gaps. We’ll explain what a research gap is, look at the four most common types of research gaps, and unpack how you can go about finding a suitable research gap for your dissertation, thesis or research project.

Overview: Research Gap 101

• What is a research gap
• Four common types of research gaps
• Practical examples
• How to find research gaps
• Recap & key takeaways

What (exactly) is a research gap?

Well, at the simplest level, a research gap is essentially an unanswered question or unresolved problem in a field, which reflects a lack of existing research in that space. Alternatively, a research gap can also exist when there’s already a fair deal of existing research, but where the findings of the studies pull in different directions , making it difficult to draw firm conclusions.

For example, let’s say your research aims to identify the cause (or causes) of a particular disease. Upon reviewing the literature, you may find that there’s a body of research that points toward cigarette smoking as a key factor – but at the same time, a large body of research that finds no link between smoking and the disease. In that case, you may have something of a research gap that warrants further investigation.

Now that we’ve defined what a research gap is – an unanswered question or unresolved problem – let’s look at a few different types of research gaps.

Types of research gaps

While there are many different types of research gaps, the four most common ones we encounter when helping students at Grad Coach are as follows:

• The classic literature gap
• The disagreement gap
• The contextual gap, and
• The methodological gap

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1. The Classic Literature Gap

First up is the classic literature gap. This type of research gap emerges when there’s a new concept or phenomenon that hasn’t been studied much, or at all. For example, when a social media platform is launched, there’s an opportunity to explore its impacts on users, how it could be leveraged for marketing, its impact on society, and so on. The same applies for new technologies, new modes of communication, transportation, etc.

Classic literature gaps can present exciting research opportunities , but a drawback you need to be aware of is that with this type of research gap, you’ll be exploring completely new territory . This means you’ll have to draw on adjacent literature (that is, research in adjacent fields) to build your literature review, as there naturally won’t be very many existing studies that directly relate to the topic. While this is manageable, it can be challenging for first-time researchers, so be careful not to bite off more than you can chew.

2. The Disagreement Gap

As the name suggests, the disagreement gap emerges when there are contrasting or contradictory findings in the existing research regarding a specific research question (or set of questions). The hypothetical example we looked at earlier regarding the causes of a disease reflects a disagreement gap.

Importantly, for this type of research gap, there needs to be a relatively balanced set of opposing findings . In other words, a situation where 95% of studies find one result and 5% find the opposite result wouldn’t quite constitute a disagreement in the literature. Of course, it’s hard to quantify exactly how much weight to give to each study, but you’ll need to at least show that the opposing findings aren’t simply a corner-case anomaly .

3. The Contextual Gap

The third type of research gap is the contextual gap. Simply put, a contextual gap exists when there’s already a decent body of existing research on a particular topic, but an absence of research in specific contexts .

For example, there could be a lack of research on:

• A specific population – perhaps a certain age group, gender or ethnicity
• A geographic area – for example, a city, country or region
• A certain time period – perhaps the bulk of the studies took place many years or even decades ago and the landscape has changed.

The contextual gap is a popular option for dissertations and theses, especially for first-time researchers, as it allows you to develop your research on a solid foundation of existing literature and potentially even use existing survey measures.

Importantly, if you’re gonna go this route, you need to ensure that there’s a plausible reason why you’d expect potential differences in the specific context you choose. If there’s no reason to expect different results between existing and new contexts, the research gap wouldn’t be well justified. So, make sure that you can clearly articulate why your chosen context is “different” from existing studies and why that might reasonably result in different findings.

4. The Methodological Gap

Last but not least, we have the methodological gap. As the name suggests, this type of research gap emerges as a result of the research methodology or design of existing studies. With this approach, you’d argue that the methodology of existing studies is lacking in some way , or that they’re missing a certain perspective.

For example, you might argue that the bulk of the existing research has taken a quantitative approach, and therefore there is a lack of rich insight and texture that a qualitative study could provide. Similarly, you might argue that existing studies have primarily taken a cross-sectional approach , and as a result, have only provided a snapshot view of the situation – whereas a longitudinal approach could help uncover how constructs or variables have evolved over time.

Practical Examples

Let’s take a look at some practical examples so that you can see how research gaps are typically expressed in written form. Keep in mind that these are just examples – not actual current gaps (we’ll show you how to find these a little later!).

Context: Healthcare

Despite extensive research on diabetes management, there’s a research gap in terms of understanding the effectiveness of digital health interventions in rural populations (compared to urban ones) within Eastern Europe.

Context: Environmental Science

While a wealth of research exists regarding plastic pollution in oceans, there is significantly less understanding of microplastic accumulation in freshwater ecosystems like rivers and lakes, particularly within Southern Africa.

Context: Education

While empirical research surrounding online learning has grown over the past five years, there remains a lack of comprehensive studies regarding the effectiveness of online learning for students with special educational needs.

As you can see in each of these examples, the author begins by clearly acknowledging the existing research and then proceeds to explain where the current area of lack (i.e., the research gap) exists.

How To Find A Research Gap

Now that you’ve got a clearer picture of the different types of research gaps, the next question is of course, “how do you find these research gaps?” .

Well, we cover the process of how to find original, high-value research gaps in a separate post . But, for now, I’ll share a basic two-step strategy here to help you find potential research gaps.

As a starting point, you should find as many literature reviews, systematic reviews and meta-analyses as you can, covering your area of interest. Additionally, you should dig into the most recent journal articles to wrap your head around the current state of knowledge. It’s also a good idea to look at recent dissertations and theses (especially doctoral-level ones). Dissertation databases such as ProQuest, EBSCO and Open Access are a goldmine for this sort of thing. Importantly, make sure that you’re looking at recent resources (ideally those published in the last year or two), or the gaps you find might have already been plugged by other researchers.

Once you’ve gathered a meaty collection of resources, the section that you really want to focus on is the one titled “ further research opportunities ” or “further research is needed”. In this section, the researchers will explicitly state where more studies are required – in other words, where potential research gaps may exist. You can also look at the “ limitations ” section of the studies, as this will often spur ideas for methodology-based research gaps.

By following this process, you’ll orient yourself with the current state of research , which will lay the foundation for you to identify potential research gaps. You can then start drawing up a shortlist of ideas and evaluating them as candidate topics . But remember, make sure you’re looking at recent articles – there’s no use going down a rabbit hole only to find that someone’s already filled the gap 🙂

Let’s Recap

We’ve covered a lot of ground in this post. Here are the key takeaways:

• A research gap is an unanswered question or unresolved problem in a field, which reflects a lack of existing research in that space.
• The four most common types of research gaps are the classic literature gap, the disagreement gap, the contextual gap and the methodological gap.
• To find potential research gaps, start by reviewing recent journal articles in your area of interest, paying particular attention to the FRIN section .

If you’re keen to learn more about research gaps and research topic ideation in general, be sure to check out the rest of the Grad Coach Blog . Alternatively, if you’re looking for 1-on-1 support with your dissertation, thesis or research project, be sure to check out our private coaching service .

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43 Comments

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it very good but what need to be clear with the concept is when di we use research gap before we conduct aresearch or after we finished it ,or are we propose it to be solved or studied or to show that we are unable to cover so that we let it to be studied by other researchers ?

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Doing research in PhD accounting, my research topic is: Business Environment and Small Business Performance: The Moderating Effect of Financial Literacy in Eastern Uganda. I am failing to focus the idea in the accounting areas. my supervisor tells me my research is more of in the business field. the literature i have surveyed has used financial literacy as an independent variable and not as a moderator. Kindly give me some guidance here. the core problem is that despite the various studies, small businesses continue to collapse in the region. my vision is that financial literacy is still one of the major challenges hence the need for this topic.

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Home » Research Gap – Types, Examples and How to Identify

Research Gap – Types, Examples and How to Identify

Table of Contents

Research Gap

Definition:

Research gap refers to an area or topic within a field of study that has not yet been extensively researched or is yet to be explored. It is a question, problem or issue that has not been addressed or resolved by previous research.

How to Identify Research Gap

Identifying a research gap is an essential step in conducting research that adds value and contributes to the existing body of knowledge. Research gap requires critical thinking, creativity, and a thorough understanding of the existing literature . It is an iterative process that may require revisiting and refining your research questions and ideas multiple times.

Here are some steps that can help you identify a research gap:

• Review existing literature: Conduct a thorough review of the existing literature in your research area. This will help you identify what has already been studied and what gaps still exist.
• Identify a research problem: Identify a specific research problem or question that you want to address.
• Analyze existing research: Analyze the existing research related to your research problem. This will help you identify areas that have not been studied, inconsistencies in the findings, or limitations of the previous research.
• Brainstorm potential research ideas : Based on your analysis, brainstorm potential research ideas that address the identified gaps.
• Consult with experts: Consult with experts in your research area to get their opinions on potential research ideas and to identify any additional gaps that you may have missed.
• Refine research questions: Refine your research questions and hypotheses based on the identified gaps and potential research ideas.
• Develop a research proposal: Develop a research proposal that outlines your research questions, objectives, and methods to address the identified research gap.

Types of Research Gap

There are different types of research gaps that can be identified, and each type is associated with a specific situation or problem. Here are the main types of research gaps and their explanations:

Theoretical Gap

This type of research gap refers to a lack of theoretical understanding or knowledge in a particular area. It can occur when there is a discrepancy between existing theories and empirical evidence or when there is no theory that can explain a particular phenomenon. Identifying theoretical gaps can lead to the development of new theories or the refinement of existing ones.

Empirical Gap

An empirical gap occurs when there is a lack of empirical evidence or data in a particular area. It can happen when there is a lack of research on a specific topic or when existing research is inadequate or inconclusive. Identifying empirical gaps can lead to the development of new research studies to collect data or the refinement of existing research methods to improve the quality of data collected.

Methodological Gap

This type of research gap refers to a lack of appropriate research methods or techniques to answer a research question. It can occur when existing methods are inadequate, outdated, or inappropriate for the research question. Identifying methodological gaps can lead to the development of new research methods or the modification of existing ones to better address the research question.

Practical Gap

A practical gap occurs when there is a lack of practical applications or implementation of research findings. It can occur when research findings are not implemented due to financial, political, or social constraints. Identifying practical gaps can lead to the development of strategies for the effective implementation of research findings in practice.

Knowledge Gap

This type of research gap occurs when there is a lack of knowledge or information on a particular topic. It can happen when a new area of research is emerging, or when research is conducted in a different context or population. Identifying knowledge gaps can lead to the development of new research studies or the extension of existing research to fill the gap.

Examples of Research Gap

Here are some examples of research gaps that researchers might identify:

• Theoretical Gap Example : In the field of psychology, there might be a theoretical gap related to the lack of understanding of the relationship between social media use and mental health. Although there is existing research on the topic, there might be a lack of consensus on the mechanisms that link social media use to mental health outcomes.
• Empirical Gap Example : In the field of environmental science, there might be an empirical gap related to the lack of data on the long-term effects of climate change on biodiversity in specific regions. Although there might be some studies on the topic, there might be a lack of data on the long-term effects of climate change on specific species or ecosystems.
• Methodological Gap Example : In the field of education, there might be a methodological gap related to the lack of appropriate research methods to assess the impact of online learning on student outcomes. Although there might be some studies on the topic, existing research methods might not be appropriate to assess the complex relationships between online learning and student outcomes.
• Practical Gap Example: In the field of healthcare, there might be a practical gap related to the lack of effective strategies to implement evidence-based practices in clinical settings. Although there might be existing research on the effectiveness of certain practices, they might not be implemented in practice due to various barriers, such as financial constraints or lack of resources.
• Knowledge Gap Example: In the field of anthropology, there might be a knowledge gap related to the lack of understanding of the cultural practices of indigenous communities in certain regions. Although there might be some research on the topic, there might be a lack of knowledge about specific cultural practices or beliefs that are unique to those communities.

Examples of Research Gap In Literature Review, Thesis, and Research Paper might be:

• Literature review : A literature review on the topic of machine learning and healthcare might identify a research gap in the lack of studies that investigate the use of machine learning for early detection of rare diseases.
• Thesis : A thesis on the topic of cybersecurity might identify a research gap in the lack of studies that investigate the effectiveness of artificial intelligence in detecting and preventing cyber attacks.
• Research paper : A research paper on the topic of natural language processing might identify a research gap in the lack of studies that investigate the use of natural language processing techniques for sentiment analysis in non-English languages.

How to Write Research Gap

By following these steps, you can effectively write about research gaps in your paper and clearly articulate the contribution that your study will make to the existing body of knowledge.

Here are some steps to follow when writing about research gaps in your paper:

• Identify the research question : Before writing about research gaps, you need to identify your research question or problem. This will help you to understand the scope of your research and identify areas where additional research is needed.
• Review the literature: Conduct a thorough review of the literature related to your research question. This will help you to identify the current state of knowledge in the field and the gaps that exist.
• Identify the research gap: Based on your review of the literature, identify the specific research gap that your study will address. This could be a theoretical, empirical, methodological, practical, or knowledge gap.
• Provide evidence: Provide evidence to support your claim that the research gap exists. This could include a summary of the existing literature, a discussion of the limitations of previous studies, or an analysis of the current state of knowledge in the field.
• Explain the importance: Explain why it is important to fill the research gap. This could include a discussion of the potential implications of filling the gap, the significance of the research for the field, or the potential benefits to society.
• State your research objectives: State your research objectives, which should be aligned with the research gap you have identified. This will help you to clearly articulate the purpose of your study and how it will address the research gap.

Importance of Research Gap

The importance of research gaps can be summarized as follows:

• Advancing knowledge: Identifying research gaps is crucial for advancing knowledge in a particular field. By identifying areas where additional research is needed, researchers can fill gaps in the existing body of knowledge and contribute to the development of new theories and practices.
• Guiding research: Research gaps can guide researchers in designing studies that fill those gaps. By identifying research gaps, researchers can develop research questions and objectives that are aligned with the needs of the field and contribute to the development of new knowledge.
• Enhancing research quality: By identifying research gaps, researchers can avoid duplicating previous research and instead focus on developing innovative research that fills gaps in the existing body of knowledge. This can lead to more impactful research and higher-quality research outputs.
• Informing policy and practice: Research gaps can inform policy and practice by highlighting areas where additional research is needed to inform decision-making. By filling research gaps, researchers can provide evidence-based recommendations that have the potential to improve policy and practice in a particular field.

Applications of Research Gap

Here are some potential applications of research gap:

• Informing research priorities: Research gaps can help guide research funding agencies and researchers to prioritize research areas that require more attention and resources.
• Identifying practical implications: Identifying gaps in knowledge can help identify practical applications of research that are still unexplored or underdeveloped.
• Stimulating innovation: Research gaps can encourage innovation and the development of new approaches or methodologies to address unexplored areas.
• Improving policy-making: Research gaps can inform policy-making decisions by highlighting areas where more research is needed to make informed policy decisions.
• Enhancing academic discourse: Research gaps can lead to new and constructive debates and discussions within academic communities, leading to more robust and comprehensive research.

Advantages of Research Gap

Here are some of the advantages of research gap:

• Identifies new research opportunities: Identifying research gaps can help researchers identify areas that require further exploration, which can lead to new research opportunities.
• Improves the quality of research: By identifying gaps in current research, researchers can focus their efforts on addressing unanswered questions, which can improve the overall quality of research.
• Enhances the relevance of research: Research that addresses existing gaps can have significant implications for the development of theories, policies, and practices, and can therefore increase the relevance and impact of research.
• Helps avoid duplication of effort: Identifying existing research can help researchers avoid duplicating efforts, saving time and resources.
• Helps to refine research questions: Research gaps can help researchers refine their research questions, making them more focused and relevant to the needs of the field.
• Promotes collaboration: By identifying areas of research that require further investigation, researchers can collaborate with others to conduct research that addresses these gaps, which can lead to more comprehensive and impactful research outcomes.

Disadvantages of Research Gap

While research gaps can be advantageous, there are also some potential disadvantages that should be considered:

• Difficulty in identifying gaps: Identifying gaps in existing research can be challenging, particularly in fields where there is a large volume of research or where research findings are scattered across different disciplines.
• Lack of funding: Addressing research gaps may require significant resources, and researchers may struggle to secure funding for their work if it is perceived as too risky or uncertain.
• Time-consuming: Conducting research to address gaps can be time-consuming, particularly if the research involves collecting new data or developing new methods.
• Risk of oversimplification: Addressing research gaps may require researchers to simplify complex problems, which can lead to oversimplification and a failure to capture the complexity of the issues.
• Bias : Identifying research gaps can be influenced by researchers’ personal biases or perspectives, which can lead to a skewed understanding of the field.
• Potential for disagreement: Identifying research gaps can be subjective, and different researchers may have different views on what constitutes a gap in the field, leading to disagreements and debate.

About the author

Muhammad Hassan

Researcher, Academic Writer, Web developer

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Research Process

• Brainstorming
• Explore Google This link opens in a new window
• Explore Web Resources
• Explore Background Information
• Explore Books
• Explore Scholarly Articles
• Narrowing a Topic
• Primary and Secondary Resources
• Academic, Popular & Trade Publications
• Scholarly and Peer-Reviewed Journals
• Grey Literature
• Clinical Trials
• Evidence Based Treatment
• Scholarly Research
• Database Research Log
• Search Limits
• Keyword Searching
• Boolean Operators
• Phrase Searching
• Truncation & Wildcard Symbols
• Proximity Searching
• Field Codes
• Subject Terms and Database Thesauri
• Reading a Scientific Article
• Website Evaluation
• Article Keywords and Subject Terms
• Cited References
• Citing Articles
• Related Results
• Search Within Publication
• Database Alerts & RSS Feeds
• Personal Database Accounts
• Persistent URLs
• Literature Gap and Future Research
• Web of Knowledge
• Annual Reviews
• Systematic Reviews & Meta-Analyses
• Finding Seminal Works
• Exhausting the Literature
• Finding Dissertations
• Researching Theoretical Frameworks
• Research Methodology & Design
• Tests and Measurements
• Organizing Research & Citations This link opens in a new window
• Picking Where to Publish
• Bibliometrics
• Learn the Library This link opens in a new window

Research Articles

These examples below illustrate how researchers from different disciplines identified gaps in existing literature. For additional examples, try a NavigatorSearch using this search string: ("Literature review") AND (gap*)

• Addressing the Recent Developments and Potential Gaps in the Literature of Corporate Sustainability
• Applications of Psychological Science to Teaching and Learning: Gaps in the Literature
• Attitudes, Risk Factors, and Behaviours of Gambling Among Adolescents and Young People: A Literature Review and Gap Analysis
• Do Psychological Diversity Climate, HRM Practices, and Personality Traits (Big Five) Influence Multicultural Workforce Job Satisfaction and Performance? Current Scenario, Literature Gap, and Future Research Directions
• Entrepreneurship Education: A Systematic Literature Review and Identification of an Existing Gap in the Field
• Evidence and Gaps in the Literature on HIV/STI Prevention Interventions Targeting Migrants in Receiving Countries: A Scoping Review
• Homeless Indigenous Veterans and the Current Gaps in Knowledge: The State of the Literature
• A Literature Review and Gap Analysis of Emerging Technologies and New Trends in Gambling
• A Review of Higher Education Image and Reputation Literature: Knowledge Gaps and a Research Agenda
• Trends and Gaps in Empirical Research on Open Educational Resources (OER): A Systematic Mapping of the Literature from 2015 to 2019
• Where Should We Go From Here? Identified Gaps in the Literature in Psychosocial Interventions for Youth With Autism Spectrum Disorder and Comorbid Anxiety

What is a ‘gap in the literature’?

The gap, also considered the missing piece or pieces in the research literature, is the area that has not yet been explored or is under-explored. This could be a population or sample (size, type, location, etc.), research method, data collection and/or analysis, or other research variables or conditions.

It is important to keep in mind, however, that just because you identify a gap in the research, it doesn't necessarily mean that your research question is worthy of exploration. You will want to make sure that your research will have valuable practical and/or theoretical implications. In other words, answering the research question could either improve existing practice and/or inform professional decision-making (Applied Degree), or it could revise, build upon, or create theoretical frameworks informing research design and practice (Ph.D Degree). See the Dissertation Center  for additional information about dissertation criteria at NU.

For a additional information on gap statements, see the following:

• How to Find a Gap in the Literature
• Write Like a Scientist: Gap Statements

How do you identify the gaps?

Conducting an exhaustive literature review is your first step. As you search for journal articles, you will need to read critically across the breadth of the literature to identify these gaps. You goal should be to find a ‘space’ or opening for contributing new research. The first step is gathering a broad range of research articles on your topic. You may want to look for research that approaches the topic from a variety of methods – qualitative, quantitative, or mixed methods. 

See the videos below for further instruction on identifying a gap in the literature.

Identifying a Gap in the Literature - Dr. Laurie Bedford

How Do You Identify Gaps in Literature? - SAGE Research Methods

Literature Gap & Future Research - Library Workshop

This workshop presents effective search techniques for identifying a gap in the literature and recommendations for future research.

Where can you locate research gaps?

As you begin to gather the literature, you will want to critically read for what has, and has not, been learned from the research. Use the Discussion and Future Research sections of the articles to understand what the researchers have found and where they point out future or additional research areas. This is similar to identifying a gap in the literature, however, future research statements come from a single study rather than an exhaustive search. You will want to check the literature to see if those research questions have already been answered.

Roadrunner Search

Identifying the gap in the research relies on an exhaustive review of the literature. Remember, researchers may not explicitly state that a gap in the literature exists; you may need to thoroughly review and assess the research to make that determination yourself.

However, there are techniques that you can use when searching in NavigatorSearch to help identify gaps in the literature. You may use search terms such as "literature gap " or "future research" "along with your subject keywords to pinpoint articles that include these types of statements.

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How to find and fill gaps in the literature [Research Gaps Made Easy]

As we dive deeper into the realm of research, one term repeatedly echoes in the corridors of academia: “gap in literature.”

But what does it mean to find a gap in the literature, and why is it so crucial for your research project?

A gap in the literature refers to an area that hasn’t been studied or lacks substantial inquiry in your field of study. Identifying such gaps allows you to contribute fresh insights and innovation, thereby extending the existing body of knowledge.

It’s the cornerstone for every dissertation or research paper, setting the stage for an introduction that explicitly outlines the scope and aim of your investigation.

This gap review isn’t limited to what has been published in peer-reviewed journals; it may also include conference papers, dissertations, or technical reports, i.e., types of papers that provide an overview of ongoing research. 

This step is where your detective work comes in—by spotting trends, common methodologies, and unanswered questions, you can unearth an opportunity to explore an unexplored domain, thereby finding a research gap. 

Why Looking for Research Gaps is Essential

Looking for research gaps is essential as it enables the discovery of novel and unique contributions to a particular field.

By identifying these gaps, found through methods such as analyzing concluding remarks of recent papers, literature reviews, examining research groups’ non-peer-reviewed outputs, and utilizing specific search terms on Google Scholar, one can discern the trajectory of ongoing research and unearth opportunities for original inquiry.

These gaps highlight areas of potential innovation, unexplored paths, and disputed concepts, serving as the catalyst for valuable contributions and progression in the field. Hence, finding research gaps forms the basis of substantial and impactful scientific exploration.

Then your research can contribute by finding and filling the gap in knowledge. 

Method 1: Utilizing Concluding Remarks of Recent Research

When embarking on a quest to find research gaps, the concluding remarks of recent research papers can serve as an unexpected treasure map.

This section of a paper often contains insightful comments on the limitations of the work and speculates on future research directions.

These comments, although not directly pointing to a research gap, can hint at where the research is heading and what areas require further exploration.

Consider these remarks as signposts, pointing you towards uncharted territories in your field of interest.

For example, you may come across a conclusion in a recent paper on artificial intelligence that indicates a need for more research on ethical considerations. This gives you a direction to explore – the ethical implications of AI. 

However, it’s important to bear in mind that while these statements provide valuable leads, they aren’t definitive indicators of research gaps. They provide a starting point, a clue to the vast research puzzle.

Your task is to take these hints, explore further, and discern the most promising areas for your investigation. It’s a bit like being a detective, except your clues come from scholarly papers instead of crime scenes!

Method 2: Examining Research Groups and Non-peer Reviewed Outputs

If concluding remarks are signposts to potential research gaps, non-peer reviewed outputs such as preprints, conference presentations, and dissertations are detailed maps guiding you towards the frontier of research.

These resources reflect the real-time development in the field, giving you a sense of the “buzz” that surrounds hot topics.

These materials, presented but not formally published, offer a sneak peek into ongoing studies, providing you with a rich source of information to identify emerging trends and potential research gaps.

For instance, a presentation on the impact of climate change on mental health might reveal a new line of research that’s in its early stages.

One word of caution: while these resources can be enlightening, they have not undergone the rigorous peer review process that published articles have.

This means the quality of research may vary and the findings should be interpreted with a critical eye. Remember, the key is to pinpoint where the research is heading and then carve out your niche within that sphere.

Exploring non-peer reviewed outputs allows you to stay ahead of the curve, harnessing the opportunity to investigate and contribute to a burgeoning area of study before it becomes mainstream.

Method 3: Searching for ‘Promising’ and ‘Preliminary’ Results on Google Scholar

With a plethora of research at your fingertips, Google Scholar can serve as a remarkable tool in your quest to discover research gaps. The magic lies in a simple trick: search for the phrases “promising results” or “preliminary results” within your research area. Why these specific phrases? Scientists often use them when they have encouraging but not yet fully verified findings.

To illustrate, consider an example. Type “promising results and solar cell” into Google Scholar, and filter by recent publications.

The search results will show you recent studies where researchers have achieved promising outcomes but may not have fully developed their ideas or resolved all challenges.

These “promising” or “preliminary” results often represent areas ripe for further exploration.

They hint at a research question that has been opened but not fully answered. However, tread carefully.

While these findings can indeed point to potential research gaps, they can also lead to dead ends. It’s crucial to examine these leads with a critical eye and further corroborate them with a comprehensive review of related research.

Nevertheless, this approach provides a simple, effective starting point for identifying research gaps, serving as a launchpad for your explorations.

Method 4: Reading Around the Subject

Comprehensive reading forms the bedrock of effective research. When hunting for research gaps, you need to move beyond just the preliminary findings and delve deeper into the context surrounding these results.

This involves broadening your view and reading extensively around your topic of interest.

In the course of your reading, you will start identifying common themes, reoccurring questions, and shared challenges in the research.

Over time, patterns will emerge, helping you recognize areas where research is thin or missing.

For instance, in studying autonomous vehicles, you might find recurring questions about regulatory frameworks, pointing to a potential gap in the legal aspects of this technology.

However, this method is not about scanning through a huge volume of literature aimlessly. It involves strategic and critical reading, looking for patterns, inconsistencies, and areas where the existing literature falls short.

It’s akin to painting a picture where some parts are vividly detailed while others remain sketchy. Your goal is to identify these sketchy areas and fill in the details.

So grab your academic reading list, and start diving into the ocean of knowledge. Remember, it’s not just about the depth, but also the breadth of your reading, that will lead you to a meaningful research gap.

Method 5: Consulting with Current Researchers

Few methods are as effective in uncovering research gaps as engaging in conversations with active researchers in your field of interest.

Current researchers, whether they are PhD students, postdoctoral researchers, or supervisors, are often deeply engaged in ongoing studies and understand the current challenges in their respective fields.

Start by expressing genuine interest in their work. Rather than directly asking for research gaps, inquire about the challenges they are currently facing in their projects.

You can ask, “What are the current challenges in your research?”

Their responses can highlight potential areas of exploration, setting you on the path to identifying meaningful research gaps.

Moreover, supervisors, particularly those overseeing PhD and Master’s students, often have ideas for potential research topics. By asking the right questions, you can tap into their wealth of knowledge and identify fruitful areas of study.

While the act of discovering research gaps can feel like a solitary journey, it doesn’t have to be.

Engaging with others who are grappling with similar challenges can provide valuable insights and guide your path. After all, the world of research thrives on collaboration and shared intellectual curiosity.

Method 6: Utilizing Online Tools

The digital age has made uncovering research gaps easier, thanks to a plethora of online tools that help visualize the interconnectedness of research literature.

Platforms such as:

• Connected Papers,
• ResearchRabbit, and

allow you to see how different papers in your field relate to one another, thereby creating a web of knowledge.

Upon creating this visual web, you may notice that many papers point towards a certain area, but then abruptly stop. This could indicate a potential research gap, suggesting that the topic hasn’t been adequately addressed or has been sidelined for some reason.

By further reading around this apparent gap, you can understand if it’s a genuine knowledge deficit or merely a research path that was abandoned due to inherent challenges or a dead end.

These online tools provide a bird’s eye view of the literature, helping you understand the broader landscape of research in your area of interest.

By examining patterns and relationships among studies, you can effectively zero in on unexplored areas, making these tools a valuable asset in your quest for research gaps.

Method 7: Seeking Conflicting Ideas in the Literature

In scientific research, areas of conflict can often be fertile ground for finding research gaps. These are areas where there’s a considerable amount of disagreement or ongoing debate among researchers.

If you can bring a fresh perspective, a new technique, or a novel hypothesis to such a contentious issue, you may well be on your way to uncovering a significant research gap.

Take, for instance, an area in psychology where there is a heated debate about the influence of nature versus nurture.

If you can introduce a new dimension to the debate or a method to test a novel hypothesis, you could potentially fill a significant gap in the literature.

Investigating areas of conflict not only opens avenues for exploring research gaps, but it also provides opportunities for you to make substantial contributions to your field. The key is to be able to see the potential for a new angle and to muster the courage to dive into contentious waters.

However, engaging with conflicts in research requires careful navigation.

Striking the right balance between acknowledging existing research and championing new ideas is crucial.

In the end, resolving these conflicts or adding significant depth to the debate can be incredibly rewarding and contribute greatly to your field.

The Right Perspective Towards Research Gaps

The traditional understanding of research gaps often involves seeking out a ‘bubble’ of missing knowledge in the sea of existing research, a niche yet to be explored. However, in today’s fast-paced research environment, these bubbles are becoming increasingly rare.

The paradigm of finding research gaps is shifting. It’s no longer just about seeking out holes in existing knowledge, but about understanding the leading edge of research and the directions it could take. It involves not just filling in the gaps but extending the boundaries of knowledge.

To identify such opportunities, develop a comprehensive understanding of the research landscape, identify emerging trends, and keep a close eye on recent advancements.

Look for the tendrils of knowledge extending out into the unknown and think about how you can push them further. It might be a challenging task, but it offers the potential for making substantial, impactful contributions to your field. 

Remember, every great innovation begins at the edge of what is known. That’s where your research gap might be hiding.

Wrapping up – Literature and research gaps

Finding and filling a gap in the literature is a task crucial to every research project. It begins with a systematic review of existing literature – a quest to identify what has been studied and more importantly, what hasn’t.

You must delve into the rich terrain of literature in their field, from the seminal, citation-heavy research articles to the fresh perspective of conference papers. Identifying the gap in the literature necessitates a thorough evaluation of existing studies to refine your area of interest and map the scope and aim of your future research.

The purpose is to explicitly identify the gap that exists, so you can contribute to the body of knowledge by providing fresh insights. The process involves a series of steps, from consulting with faculty and experts in the field to identify potential trends and outdated methodologies, to being methodological in your approach to identify gaps that have emerged.

Upon finding a gap in the literature, we’ll ideally have a clearer picture of the research need and an opportunity to explore this unexplored domain.

It is important to remember that the task does not end with identifying the gap. The real challenge lies in drafting a research proposal that’s objective, answerable, and can quantify the impact of filling this gap. 

It’s important to consult with your advisor, and also look at commonly used parameters and preliminary evidence. Only then can we complete the task of turning an identified gap in the literature into a valuable contribution to your field, a contribution that’s peer-reviewed and adds to the body of knowledge.

To find a research gap is to stand on the shoulders of giants, looking beyond the existing research to further expand our understanding of the world.

Dr Andrew Stapleton has a Masters and PhD in Chemistry from the UK and Australia. He has many years of research experience and has worked as a Postdoctoral Fellow and Associate at a number of Universities. Although having secured funding for his own research, he left academia to help others with his YouTube channel all about the inner workings of academia and how to make it work for you.

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Robinson KA, Akinyede O, Dutta T, et al. Framework for Determining Research Gaps During Systematic Review: Evaluation [Internet]. Rockville (MD): Agency for Healthcare Research and Quality (US); 2013 Feb.

Framework for Determining Research Gaps During Systematic Review: Evaluation [Internet].

Introduction.

The identification of gaps from systematic reviews is essential to the practice of “evidence-based research.” Health care research should begin and end with a systematic review. 1 - 3 A comprehensive and explicit consideration of the existing evidence is necessary for the identification and development of an unanswered and answerable question, for the design of a study most likely to answer that question, and for the interpretation of the results of the study. 4

In a systematic review, the consideration of existing evidence often highlights important areas where deficiencies in information limit our ability to make decisions. We define a research gap as a topic or area for which missing or inadequate information limits the ability of reviewers to reach a conclusion for a given question. A research gap may be further developed, such as through stakeholder engagement in prioritization, into research needs. Research needs are those areas where the gaps in the evidence limit decision making by patients, clinicians, and policy makers. A research gap may not be a research need if filling the gap would not be of use to stakeholders that make decisions in health care. The clear and explicit identification of research gaps is a necessary step in developing a research agenda. Evidence reports produced by Evidence-based Practice Centers (EPCs) have always included a future research section. However, in contrast to the explicit and transparent steps taken in the completion of a systematic review, there has not been a systematic process for the identification of research gaps.

In a prior methods project, our EPC set out to identify and pilot test a framework for the identification of research gaps. 5 , 6 We searched the literature, conducted an audit of EPC evidence reports, and sought information from other organizations which conduct evidence synthesis. Despite these efforts, we identified little detail or consistency in the frameworks used to determine research gaps within systematic reviews. In general, we found no widespread use or endorsement of a specific formal process or framework for identifying research gaps using systematic reviews.

We developed a framework to systematically identify research gaps from systematic reviews. This framework facilitates the classification of where the current evidence falls short and why the evidence falls short. The framework included two elements: (1) the characterization the gaps and (2) the identification and classification of the reason(s) for the research gap.

The PICOS structure (Population, Intervention, Comparison, Outcome and Setting) was used in this framework to describe questions or parts of questions inadequately addressed by the evidence synthesized in the systematic review. The issue of timing, sometimes included as PICOTS, was considered separately for Intervention, Comparison, and Outcome. The PICOS elements were the only sort of framework we had identified in an audit of existing methods for the identification of gaps used by EPCs and other related organizations (i.e., health technology assessment organizations). We chose to use this structure as it is one familiar to EPCs, and others, in developing questions.

It is not only important to identify research gaps but also to determine how the evidence falls short, in order to maximally inform researchers, policy makers, and funders on the types of questions that need to be addressed and the types of studies needed to address these questions. Thus, the second element of the framework was the classification of the reasons for the existence of a research gap. For each research gap, the reason(s) that most preclude conclusions from being made in the systematic review is chosen by the review team completing the framework. To leverage work already being completed by review teams, we mapped the reasons for research gaps to concepts from commonly used evidence grading systems. Briefly, these categories of reasons, explained in detail in the prior JHU EPC report 5 , are:

• Insufficient or imprecise information
• Biased information
• Inconsistent or unknown consistency results
• Not the right information

The framework facilitates a systematic approach to identifying research gaps and the reasons for those gaps. The identification of where the evidence falls short and how the evidence falls short is essential to the development of important research questions and in providing guidance in how to address these questions.

As part of the previous methods product, we developed a worksheet and instructions to facilitate the use of the framework when completing a systematic review (See Appendix A ). Preliminary evaluation of the framework and worksheet was completed by applying the framework to two completed EPC evidence reports. The framework was further refined through peer review. In this current project, we extend our work on this research gaps framework.

Our objective in this project was to complete two types of further evaluation: (1) application of the framework across a larger sample of existing systematic reviews in different topic areas, and (2) implementation of the framework by EPCs. These two objectives were used to evaluate the framework and instructions for usability and to evaluate the application of the framework by others, outside of our EPC, including as part of the process of completing an EPC report. Our overall goal was to produce a revised framework with guidance that could be used by EPCs to explicitly identify research gaps from systematic reviews.

• Cite this Page Robinson KA, Akinyede O, Dutta T, et al. Framework for Determining Research Gaps During Systematic Review: Evaluation [Internet]. Rockville (MD): Agency for Healthcare Research and Quality (US); 2013 Feb. Introduction.
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Identifying Research Gaps and Prioritizing Psychological Health Evidence Synthesis Needs

Susanne hempel , phd, kristie gore , phd, bradley belsher , phd.

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Reprints: Susanne Hempel, PhD, RAND Corporation, Evidence-based Practice Center (EPC), 1776 Main Street, Santa Monica, CA 90407. E-mail: [email protected] .

Corresponding author.

Issue date 2019 Oct.

This is an open-access article distributed under the terms of the Creative Commons Attribution-Non Commercial-No Derivatives License 4.0 (CCBY-NC-ND), where it is permissible to download and share the work provided it is properly cited. The work cannot be changed in any way or used commercially without permission from the journal. http://creativecommons.org/licenses/by-nc-nd/4.0/

Supplemental Digital Content is available in the text.

Key Words: evidence review, evidence synthesis, gap analysis, research prioritization, translational science

Background:

Evidence synthesis is key in promoting evidence-based health care, but it is resource-intense. Methods are needed to identify and prioritize evidence synthesis needs within health care systems. We describe a collaboration between an agency charged with facilitating the implementation of evidence-based research and practices across the Military Health System and a research center specializing in evidence synthesis.

Scoping searches targeted 15 sources, including the Veterans Affairs/Department of Defense Guidelines and National Defense Authorization Acts. We screened for evidence gaps in psychological health management approaches relevant to the target population. We translated gaps into potential topics for evidence maps and/or systematic reviews. Gaps amenable to evidence synthesis format provided the basis for stakeholder input. Stakeholders rated topics for their potential to inform psychological health care in the military health system. Feasibility scans determined whether topics were ready to be pursued, that is, sufficient literature exists, and duplicative efforts are avoided.

We identified 58 intervention, 9 diagnostics, 12 outcome, 19 population, and 24 health services evidence synthesis gaps. Areas included: posttraumatic stress disorder (PTSD) (19), suicide prevention (14), depression (9), bipolar disorder (9), substance use (24), traumatic brain injury (20), anxiety (1), and cross-cutting (14) synthesis topics. Stakeholder input helped prioritize 19 potential PTSD topics and 22 other psychological health topics. To date, 46 topics have undergone feasibility scans. We document lessons learned across clinical topics and research methods.

Conclusion:

We describe a transparent and structured approach to evidence synthesis topic selection for a health care system using scoping searches, translation into evidence synthesis format, stakeholder input, and feasibility scans.

Evidence synthesis is an essential step in promoting evidence-based medicine across health systems; it facilitates the translation of research to practice. A systematic review of the research literature on focused review questions is a key evidence synthesis approach that can inform practice and policy decisions. 1 However, systematic reviews are resource-intense undertakings. In a resource-constrained environment, before an evidence review is commissioned, the need and the feasibility of the review must be established.

Establishing the need for the review can be achieved through a research gap analysis or needs assessment. Identification of a gap serves as the first step in developing a new research question. 2 Research gaps in health care do not necessarily align directly with research needs. Research gaps are only critical where knowledge gaps substantially inhibit the decision-making ability of stakeholders such as patients, health care providers, and policymakers, thus creating a need to fill the knowledge gap. Evidence synthesis enables the assessment of whether a research gap continues to exist or whether there is adequate evidence to close the knowledge gap.

Furthermore, a gap analysis often identifies multiple, competing gaps that are worthwhile to be pursued. Given the resource requirements of formal evidence reviews, topic prioritization is needed to best allocate resources to those areas deemed the most relevant for the health system. Regardless of the topic, the prioritization process is likely to be stakeholder-dependent. Priorities for evidence synthesis will vary depending on the mission of the health care system and the local needs of the health care stakeholders. A process of stakeholder input is an important mechanism to ensure that the evidence review will meet local needs as well to identify a receptive audience of the review findings.

In addition to establishing the need for an evidence review, the feasibility of conducting the review must also be established. In conducting primary research, feasibility is often mainly a question of available resources. For evidence reviews, the resources, the availability of primary research, and the presence of existing evidence reviews on the topic need to be explored. Not all topics are amenable for a systematic review which focus on a specific range of research questions and rely heavily on published literature. Furthermore, evidence review synthesizes the existing evidence; hence, if there is insufficient evidence in the primary research literature, an evidence review is not useful. Establishing a lack of evidence is a worthwhile exercise since it identifies the need for further research. However, most health care delivery organizations will be keen to prioritize areas that can be synthesized, that is, investing in synthesizing a body of research sizable enough to derive meaningful results. For evidence reviews, the presence of existing evidence syntheses is also an important consideration, in particular, to determine the incremental validity of a new review. Although primary research benefits profoundly by replication, secondary literature, in particular in the context of existing high-quality reviews and/or limited evidence, may not add anything to our knowledge base. 3

This work describes a structured and transparent approach to identify and prioritize areas of psychological health that are important and that can be feasibly addressed by a synthesis of the research literature. It describes a collaboration between an agency charged with facilitating the implementation of evidence-based research and practices across the Military Health System (MHS) and a research center specializing in evidence synthesis.

This project is anchored in the relationship between the Defense Health Agency Psychological Health Center of Excellence (PHCoE) and the RAND Corporation’s National Defense Research Institute (NDRI), one of the Federally Funded Research and Development Centers (FFRDC) dedicated to providing long-term analytic support to the Defense Health Agency. PHCoE, an agency charged with facilitating the implementation of evidence-based research and practices across the Military Health System funded a series of systematic reviews and evidence maps synthesizing psychological research. The project draws on the expertise of the Southern California Evidence-based Practice Center (EPC) located at RAND, a center specializing in evidence synthesis. The project included scoping searches, stakeholder input, and feasibility scans. The project is ongoing; this manuscript describes methods and results from June 2016 to September 2018. The project was assessed by our Human Subject Protection staff and determined to be exempt (date July 7, 2016, ID ND3621; August 6, 2017, ID ND3714).

The following describes the process, Figure 1 provides a visual overview.

Process of identifying research gaps and prioritizing psychological health evidence synthesis needs.

Scoping Searches to Identify Evidence Synthesis Gaps

Scoping searches targeted pertinent sources for evidence gaps. The searches focused on clinical conditions and interventions relevant to psychological health, including biological psychiatry, health care services research, and mental health comorbidity. Proposed topics and study populations were not limited by deployment status or deployment eligibility, but the topic section considered the prevalence of clinical conditions among Department of Defense active duty military personnel managed by the MHS. The scoping searches excluded evidence gaps addressing children and adolescents and clinical conditions exclusively relevant to veterans managed by the Department of Veterans Affairs.

Scoping Search Sources

We screened 15 sources in total for evidence synthesis gaps.

Veterans Affairs/Department of Defense clinical practice guidelines were a key source for documented evidence gaps. 4 – 9 Recently updated guidelines were screened only for evidence gaps that indicated a lack of synthesis of existing research or content areas that were outside the scope of that guideline (guidelines rely primarily on published systematic reviews and can only review a limited number of topic areas).

We consulted the current report of the committee on armed services of the House of Representatives regarding the proposed National Defense Authorization Act (NDAA) and the report for the upcoming fiscal year. 10 , 11 We specifically screened the report for research priorities identified for psychological health. We also screened the published National Research Action Plan designed to improve access to mental health services for veterans, service members, and military families. 12

We conducted a literature search for publications dedicated to identifying evidence gaps and research needs for psychological health and traumatic brain injury. We searched for publications published since 2000–2016 in the most relevant databases, PubMed and PsycINFO, that had the words research gap, knowledge gap, or research priority in the title and addressed psychological health (Supplemental Digital Content, http://links.lww.com/MLR/B836 ). The search retrieved 203 citations. Six publications were considered potentially relevant and obtained as full text, 1 source was subsequently excluded because the authors conducted a literature search <3 years ago and it was deemed unlikely that a new review would identify substantially more eligible studies. 13 – 19

We also used an analysis of the utilization of complementary and alternative medicine in the MHS 20 to identify interventions that were popular with patients but for which potentially little evidence-based guidance exists. We focused our scoping efforts on complementary approaches such as stress management, hypnotherapy, massage, biofeedback, chiropractic, and music therapy to align with the funding scope. In the next step, we reviewed the existing clinical practice guidelines to determine whether clinicians have guidance regarding these approaches. The Department of Defense Health Related Behaviors Survey of Active Duty Military Personnel 21 is an anonymous survey conducted every 3 years on service members with the aim of identifying interventions or health behaviors patients currently use. To address evidence gaps most relevant to patients, we screened the survey results, and then matched the more prevalent needs identified with guidance provided in relevant clinical practice guidelines.

We consulted the priority review list assembled by the Cochrane group to identify research needs for systematic reviews. We screened the 2015–2017 lists for mental health topics that are open to new authors, that is, those that do not have an author team currently dedicated to the topic. None of the currently available topics appeared relevant to psychological health and no topics were added to the table. We also consulted with ongoing federally funded projects to identify evidence gaps that were beyond the scope of the other projects. In addition, we screened a list of psychological health research priorities developed at PHCoE for knowledge gaps that could be addressed in systematic reviews or evidence maps. Finally, we screened resources available on MHS web sites for evidence gaps.

Gap Analysis Procedure and Approach to Translating Gaps into Evidence Review Format

We first screened these sources for knowledge gaps, regardless of considerations of whether the gap is amenable to evidence review. However, we did not include research gaps where the source explicitly indicated that the knowledge gap is due to the lack of primary research. We distinguished 5 evidence gap domains and abstracted gaps across pertinent areas: interventions or diagnostic questions, treatment outcomes or specific populations, and health services research and health care delivery models.

We then translated the evidence gaps into potential topics for evidence maps and/or systematic reviews. Evidence maps provide a broad overview of large research areas using data visualizations to document the presence and absence of evidence. 22 Similar to scoping reviews, evidence maps do not necessarily address the effects of interventions but can be broader in scope. Systematic reviews are a standardized research methodology designed to answer clinical and policy questions with published research using meta-analysis to estimate effect sizes and formal grading of the quality of evidence. We considered systematic reviews for effectiveness and comparative effectiveness questions regarding specific intervention and diagnostic approaches.

Stakeholder Input

Evidence synthesis gaps that were determined to be amenable to systematic review or evidence map methods provided the basis for stakeholder input. Although all topics were reviewed by project personnel, we also identified psychological health service leads for Army, Navy, Air Force, and Marines within the Defense Health Agency as key stakeholders to be included in the topic selection process. To date, 2 rounds of formal ratings by stakeholders have been undertaken.

The first round focused on the need for systematic review covering issues related to posttraumatic stress disorder (PTSD). The second round focused on other potential psychological health topics determined to be compatible with the MHS mission. Represented clinical areas were suicide prevention and aftercare, depressive disorders, anxiety disorders, traumatic brain injury, substance use disorder including alcohol and opioid use disorder, and chronic pain. All of the potential topics addressed either the effects of clinical interventions or health service research questions.

Stakeholders rated the topics based on their potential to inform psychological health care in the military health system. The raters used a scale 5-point rating scale ranging from “No impact” to “Very high impact.” In addition, stakeholders were able to add additional suggestions for evidence review. We analyzed the mean, the mode, and individual stakeholder rating indicating “high impact” for individual topics.

Feasibility Scans

Feasibility scans provided an estimate of the volume and the type of existing research literature which is informative for 3 reasons. First, this process determined whether sufficient research was available to inform a systematic review or an evidence map. Second, feasibility scans can provide an estimate of the required resources for an evidence review by establishing whether only a small literature base or a large number of research studies exists. Finally, feasibility scans identify existing high-profile evidence synthesis reports that could make a new synthesis obsolete.

Feasibility scans for potential evidence maps concentrated on the size of the body of research that would need to be screened and the relevant synthesis questions that can inform how this research should be organized in the evidence map. Feasibility scans for systematic reviews aimed to determine the number of relevant studies, existing high-quality reviews, and the number of studies not covered in existing reviews. Randomized controlled trials (RCTs) are the focus of most of the systematic review topics, that is, strong research evidence that could inform clinical practice guideline committees to recommend either for or against interventions. An experienced systematic reviewer used PubMed, a very well-maintained and user-friendly database for biomedical literature, developed preliminary search strategies, and applied database search filters (eg, for RCTs or systematic reviews) in preliminary literature searches to estimate the research volume for each topic.

Scans also identified any existing high-quality evidence review published by agencies specializing in unbiased evidence syntheses such as the Agency for Healthcare Research and Quality (AHRQ)’s Evidence-based Practice Center program, the Cochrane Collaboration, the Campbell Collaboration, the Evidence Synthesis Program of the Department of Veterans Affairs, and the Federal Health Technology Assessment program. We used the databases PubMed and PubMed Health to identify reports. We appraised the scope, relevance and publication year of the existing high-profile evidence reviews. The research base for psychological health develops rapidly and evidence syntheses need to ensure that current clinical policies reflect the best available evidence. When determining the feasibility and appropriateness of a new systematic review, we took the results of the original review and any new studies that had been published subsequent to the systematic review on the same topic into account.

The following results are described: the results of the scoping searches and gap analysis, the translation of gaps into evidence synthesis format, the stakeholder input ratings, and the feasibility scans.

Scoping Searches and Gap Analysis Results

The scoping search and gap analysis identified a large number of evidence gaps as documented in the gap analysis table in the Appendix (Supplemental Digital Content, http://links.lww.com/MLR/B836 ). Across sources, we identified 58 intervention, 9 diagnostics, 12 outcome, 19 population, and 24 health services evidence synthesis gaps. The evidence gaps varied considerably with regard to scope and specificity, for example, highlighting knowledge gaps in recommendations for medications for specific clinical indications or treatment combinations 4 to pointing out to gaps in supporting caregivers. 11 The largest group of evidence gaps were documented for interventions. This included open questions for individual interventions (eg, ketamine) 12 as well as the best format and modality within an intervention domain (eg, use of telehealth). 6 Diagnostic evidence gaps included open questions regarding predictive risk factors that could be used in suicide prevention 8 and the need for personalized treatments. 12 Outcome evidence gaps often pointed to the lack of measured outcomes to include cost-effectiveness as well as the lack of knowledge on hypothesized effects, such as increased access or decreased stigma associated with technology-based modalities. 23 Population evidence gaps addressed specific patient populations such as complex patients 5 and family members of service members. 11 The health services evidence gaps addressed care support through technology (eg, videoconferencing 23 ) as well as treatment coordination within health care organizations such as how treatment for substance use disorder should be coordinated with treatment for co-occurring conditions. 4

Potential Evidence Synthesis Topics

The gaps were translated into potential evidence map or systematic review topics. This translation process took into account that some topics cannot easily be operationalized as an evidence review. For example, knowledge gaps regarding prevalence or utilization estimates were hindered by the lack of publicly available data. In addition, we noted that some review questions may require an exhaustive search and a full-text review of the literature because the information cannot be searched for directly, and hence were outside the budget restraints.

The clinical areas and number of topics were: PTSD (n=19), suicide prevention (n=14), depression (n=9), bipolar disorder (n=9), substance use (n=24), traumatic brain injury (n=20), anxiety (n=1), and cross-cutting (n=14) evidence synthesis topics. All topic areas are documented in the Appendix (Supplemental Digital Content, http://links.lww.com/MLR/B836 ).

Stakeholder Input Results

Stakeholders rated 19 PTSD-related research gaps and suggested an additional 5 topics for evidence review, addressing both preventions as well as treatment topics. Mean ratings for topics ranged from 1.75 to 3.5 on a scale from 0 (no impact potential) to 4 (high potential for impact). Thus, although identified as research gaps, the potential of an evidence review to have an important impact on the MHS varied across the topics. Only 2 topics received a mean score of ≥3 (high potential), including predictors of PTSD treatment retention and response and PTSD treatment dosing, duration, and sequencing . In addition, raters’ opinions varied considerably across some topics with SDs ranging from 0.5 to 1.5 across all topics.

The stakeholders rated 22 other psychological health topics, suggested 2 additional topics for evidence review, and revised 2 original topics indicating which aspect of the research gap would be most important to address. Mean scores for the rated topics ranged from 0.25 to 3.75, with the SDs for each item ranging from 0 to 1.4. Six topics received an average score of ≥3, primarily focused on the topics of suicide prevention, substance use disorders, and telehealth interventions. Opinions on other topics varied widely across service leads.

Feasibility Scan Results

Evidence review topics that were rated by stakeholders as having some potential for impact (using a rating cutoff score>1) within the MHS were selected for formal feasibility scans. To date, 46 topics have been subjected to feasibility scans. Of these, 11 were evaluated as potential evidence map, 17 as a systematic review, and 18 as either at the time of the topic suggestion. The results of the feasibility scans are documented in the table in the Appendix (Supplemental Digital Content, http://links.lww.com/MLR/B836 ).

The feasibility scan result table shows the topic, topic modification suggestions based on literature reviews, and the mean stakeholder impact rating. The table shows the employed search strategy to determine the feasibility; the estimated number of RCTs in the database PubMed; the number and citation of Cochrane, Evidence Synthesis Program, and Health Technology Assessment reviews, that is, high-quality syntheses; and the estimated number of RCTs published after the latest existing systematic review that had been published on the topic.

Each potential evidence review topic was discussed in a narrative review report that documented the reason for determining the topic to be feasible or not feasible. Reasons for determining the topic to be not feasible included the lack of primary research for an evidence map or systematic review, the presence of an ongoing research project that may influence the evidence review scope, and the presence of an existing high-quality evidence review. Some topics were shown to be feasible upon further modification; this included topics that were partially addressed in existing reviews or topics where the review scope would need to be substantially changed to result in a high-impact evidence review. Topics to be judged feasible met all outlined criteria, that is, the topic could be addressed in a systematic review or evidence map, there were sufficient studies to justify a review, and the review would not merely replicate an existing review but make a novel contribution to the evidence base.

The project describes a transparent and structured approach to identify and prioritize evidence synthesis topics using scoping reviews, stakeholder input, and feasibility scans.

The work demonstrates an approach to establishing and evaluating evidence synthesis gaps. It has been repeatedly noted that research gap analyses often lack transparency with little information on analytic criteria and selection processes. 24 , 25 In addition, research need identification may not be informed by systematic literature searches documenting gaps but primarily rely on often unstructured content expert input. 26 , 27 Evidence synthesis needs assessment is a new field that to date has received very little attention. However, as health care delivery organizations move towards providing evidence-based treatments and the existing research continue to grow, both evidence reviews and evidence review gap identification and prioritization will become more prominent.

One of the lessons learned is that the topic selection process added to the timeline and required additional resources. The scoping searches, translation into evidence synthesis topics, stakeholder input, and feasibility scans each added time and the project required a longer period of performance compared to previous evidence synthesis projects. The project components were undertaken sequentially and had to be divided into topic areas. For example, it was deemed too much to ask for stakeholder input for all 122 topics identified as potential evidence review topics. Furthermore, we needed to be flexible to be able to respond to unanticipated congressional requests for evidence reviews. However, our process of identifying synthesis gaps, checking whether topics can be translated into syntheses, obtaining stakeholder input to ensure that the gaps are meaningful and need filling, and estimating the feasibility and avoiding duplicative efforts, has merit considering the alternative. More targeted funding of evidence syntheses ensures relevance and while resources need to be spent on the steps we are describing, these are small investments compared to the resources required for a full systematic review or evidence map.

The documented stakeholder engagement approach was useful for many reasons, not just for ensuring that the selection of evidence synthesis topics was transparent and structured. The stakeholders were alerted to the evidence synthesis project and provided input for further topic refinement. This process also supported the identification of a ‘customer’ after the review was completed, that is, a stakeholder who is keen on using the evidence review is likely to take action on its results and ready to translate the findings into clinical practice. The research to practice gap is substantial and the challenges of translating research to practice are widely documented. 28 – 30 Inefficient research translation delays delivery of proven clinical practices and can lead to wasteful research and practice investments.

The project had several strengths and limitations. The project describes a successful, transparent, and structured process to engage stakeholders and identifies important and feasible evidence review topics. However, the approach was developed to address the specific military psychological health care system needs, and therefore the process may not be generalizable to all other health care delivery organizations. Source selection was tailored to psychological health synthesis needs and process modifications (ie, sources to identify gaps) are needed for organizations aiming to establish a similar procedure. To keep the approach manageable, feasibility scans used only 1 database and we developed only preliminary, not comprehensive searches. Hence, some uncertainty about the true evidence base for the different topics remained; feasibility scans can only estimate the available research. Furthermore, the selected stakeholders were limited to a small number of service leads. A broader panel of stakeholders would have likely provided additional input. In addition, all evaluations of the literature relied on the expertise of experienced systematic reviewers; any replication of the process will require some staff with expertise in the evidence review. Finally, as outlined, all described processes added to the project timeline compounding the challenges of providing timely systematic reviews for practitioners and policymakers. 31 , 32

We have described a transparent and structured approach to identify and prioritize areas of evidence synthesis for a health care system. Scoping searches and feasibility scans identified gaps in the literature that would benefit from evidence review. Stakeholder input helped ensure the relevance of review topics and created a receptive audience for targeted evidence synthesis. The approach aims to advance the field of evidence synthesis needs assessment.

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ACKNOWLEDGMENTS

The authors thank Laura Raaen, Margaret Maglione, Gulrez Azhar, Margie Danz, and Thomas Concannon for content input and Aneesa Motala and Naemma Golshan for administrative assistance.

Supported by the Office of the Secretary of Defense, Psychological Health Center of Excellence. The findings and conclusions in this manuscript are those of the authors and do not necessarily represent the views of the Psychological Health Center of Excellence, the Office of the Secretary of Defense, or the United States government.

The authors declare no conflict of interest.

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