Literature Search: How Much Research is Enough?

By Published On: September 20th, 2022Categories: Latest Publications, Literature Search and Literature ReviewTags:

The research process is often thought of as a linear, straightforward path. You begin with a question and then proceed to find the answer. But, in reality, research is a messy process that often involves more than one step.


When searching for info on a topic, it can be easy to lose sight of your purpose and how much research is enough. If you’re working on a device or product that has been in the market for a long time, it’s important to know what level of depth is required for your topic. It might feel like you need to read everything written on your subject matter, but if you don’t have time or resources for that exhaustive search, there are other options available.


So, that begs the question: How much research should I do?


A literature search aims to identify the state of knowledge on a topic to provide the context for the current study. All studies that lead up to the present study should be included in the literature review. This includes research studies conducted by others, as well as those that your team has completed. The number of articles you need to consult depends on how much relevant information has been published about your topic. Let’s dive a little deeper into how deep your research should be.

A literature search is essential in conducting a research study before developing or marketing any medical device.

Not to mention you also have to submit the literature review itself. So, it is often the first and one of the most crucial steps of getting EU MDR certified. Most companies would hire professionals to ensure an effective literature search.


Your search strategy will depend on which type of literature review you choose to do.

There are a few types of literature searches, but the most common ones are:


  • An informal review of the available scientific literature on a topic
  • A systematic review (meta-analysis) that includes all relevant studies on a specific topic and generates evidence-based conclusions regarding the effectiveness or safety of a treatment (e.g., drugs) or intervention (e.g., surgery).


For medical manufacturers, a systematic review would be appropriate.

The Purpose

An exhaustive literature search is required to identify all relevant information published on technology or device.


A literature review aims to identify the state of knowledge on a topic to provide the context for the current study.


While it may be tempting to make your work easier by limiting your search to just one set of databases (for example, PubMed), this can be risky and potentially lead to missing important results.


Essentially, the more information you find, your study will improve. If you know that other manufacturing companies have been working in the same area as yours, then it’s likely they have already done some research into this area that you might be able to use in your own research.


While performing a literature search, keep in mind that the review should include a brief summary of all previous research on the topic, including its strengths and weaknesses, as well as knowledge gaps which need to be addressed by your literature research. This will help you frame your work within this broader context and explain why it is important or necessary.

All studies that lead up to the present study should be included in the literature review.

The literature review is not only about the current study. It is also about all studies that led up to it, including those from the same or different disciplines, with similar or other approaches.


The purpose of studying all previous studies (and not just those you cite) is to avoid repeating other people’s mistakes and make use of their discoveries when designing your own research project.

How to start?


any literature search


The best place to start is a generic database. Usually, for any literature search, the first thing to consider is what you want the review to accomplish. Is it a report on the current state of knowledge? Is it an argument for new directions of treatment/ device or methods? Is it meant to be comprehensive or selective? Your research strategy should reflect this decision.


If your goal is broad coverage, you might start with something like Google Scholar, which searches millions of scholarly publications across all disciplines and subjects. However, suppose you want more control over your search terms. Based on this, you can use something like European Medical Journal, which has fewer records but allows more fine-grained searching, especially related to European cases.

How many terms are enough?

Depending on your research topic and questions, you may need to consult anywhere from 500 to 1500 articles to find all relevant information.


Nevertheless, the number of articles you’ll need to read depends on how much relevant information has been published about your topic. For example, suppose you’re searching about the effects of using medical-grade masks to prevent the long-term effects of air pollution on human health. In that case, you’ll find more relevant information by narrowing down your search terms to just “air pollution effect prevention” or “mask” than if you had used broader terms such as “air pollution” or “respiratory health.”


literature searching process, systematic reviews


An important but often missed step in conducting literature searches is ensuring that all your keywords are listed in the subject headings (also known as descriptors) assigned by databases such as PubMed. You could do it through two methods:

  1. check for any misspellings in the subject heading;
  2. remove any abbreviations from the title and replace them with their full names.


Once this has been done, and no additional misspellings or incorrect abbreviations remain within these titles, proceed with conducting an initial search using one keyword at a time.


The number of articles you need to consult depends on how much relevant information has been published about your topic. The more specific your questions, the more you need to consult. The answer to this question is not just a matter of counting words or references; it also depends on how many studies have been done in your particular area and whether any of them are particularly good at providing answers for what you want to know.


It is also important because it affects how many articles you should look at and how well-researched an article is can affect how reliable its conclusions are. So if I am looking at an article that includes 50 references, and all of them are from one basic science journal article written by one person who did two studies in a very narrow field (e.g., rats). I might want to look for other papers to validate these results.

The time frame

Should you consider the time frame of published literature while searching?


Yes, absolutely.


Research papers are published in various journals and magazines, so it’s important to consider their publication dates when searching for research, especially for clinical treatments and devices. For example, if you’re looking for research on the effects of smoking on lung cancer, you’ll need to find studies that have been published within the last 5-10 years. The reason for this is that there have been many changes to public health policy in recent years, which could have impacted how much smoking affects lung cancer rates.


For the same reason, you should try searching only in peer-reviewed journals. Again, reliable literature is key to evidence-based medicine.

How long is the search process?

There is no time limit for conducting a comprehensive literature search or writing a comprehensive literature review. Instead, it takes as long as it takes.


There is no time limit for conducting a comprehensive literature search or writing a comprehensive literature review. It takes as long as it takes. This point is where your research skills come into play.


  • Be prepared to be flexible and adapt to the situation at hand. The more experience you gain with this type of project, the easier it will be for you to make adjustments based on how things are going (or not going).
  • Search for literature with evidence-based guidelines. When you can’t find relevant articles for a keyword, try searching several databases.
  • Be willing to ask others for help if need be. If something doesn’t work out the way it should, consult with someone who knows more about literature searches than you do—even if that person isn’t your supervisor. Don’t hesitate to tap into that resource when it is needed!


To find all necessary information, we recommend searching through 4-5 databases and using up to 35 terms. It doesn’t include grey literature, but those are certainly worth a look. Sounds a tad difficult, doesn’t it? Well, there is no other way to do it, unfortunately. You don’t want to develop an entirely new device only to find a faulty critical component later because of a few missed clinical trials!

It’s not necessary to read every article from start to finish. You can skim the abstracts and conclusions for relevant information.


literature searching, literature searches, systematic reviews


Skimming is a good strategy for finding relevant information in literature searches. It allows you to quickly read the abstracts and conclusions of articles, which summarize the main points made by each paper.


You can also skim articles that you think may be relevant to your topic but aren’t sure how they will fit into your research project. This helps you decide whether you need to read every article from start to finish or if there are enough details in the abstracts and conclusions for you to use as sources.

Systematic reviews

A systematic review is better at finding all relevant information than a more informal literature review approach because it follows a formal, systematic process. In the systematic review, the researcher starts with an explicit hypothesis and then searches for studies that test it. The researcher then analyzes those studies to see if they support or refute the hypothesis.


In contrast, in an informal literature review, an author may come up with a thesis and then search for studies that support or refute it on their own. While this method can be done well – and sometimes is – it’s not as reliable because there’s no guarantee that the researcher will find all relevant information before writing their paper or book chapter.


The art of systematic reviewing consists of searching, screening, evaluating, and critically analyzing all relevant publications on your research topic and developing a study protocol that will guide your own research study towards answering your specific questions or hypotheses.


After conducting a thorough literature search, it’s time to write up your results and conclusions! This process aims to help you formulate new questions for your research study or identify gaps in current knowledge about medical devices or technology that need further exploration by others interested in conducting similar research studies on these topics.

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