OmniDocHow to draw a literature research flow chart: steps and tools
When writing a review or paper, the literature search and screening flow chart is often unclear. This article explains what to write in each box according to the four stages of "retrieval, deduplication, filtering, and inclusion", and explains how to draw a flow chart directly in the Markdown document of the UniDoc web editor, so that the diagram and the text can be placed in the same document.
Key points of this article
- The literature research flow chart is usually divided into four sections: retrieval and recording, deduplication, initial screening, re-screening and inclusion. The number of each section should match.
- Write numbers in each box, such as "420 items retrieved" and "360 items left after deduplication" so that readers can check whether the filtering is reasonable.
- The excluded documents must be classified and counted according to the reasons. You cannot just write "200 articles excluded".
- Insert icons into Markdown documents, save and export them together with the text, and you don’t need to find another drawing tool when modifying search results.
- After you finish drawing, check whether the additions and subtractions are balanced frame by frame, and confirm that the numbers in the drawing are consistent with the tables in the main text and appendix.
When writing a review, systematic review or graduation thesis, many people will be asked to attach a "literature search and screening flow chart". This picture looks like just a few boxes with arrows, but reviewers and tutors usually check numbers one by one: how many articles were retrieved, how many duplicates were removed, what reasons were excluded, and how many articles were finally included. If the numbers in the box do not match up, it is more likely to be questioned than if the words are written incorrectly.
This post is for graduate students, researchers, and course paper authors who need to draw this diagram themselves. After reading, you will know which paragraphs the flow chart should be divided into, what to write in each box, how to classify the reasons for exclusion, and how to write the flow chart directly into the document using Markdown in the UniDoc web editor. The method in this article does not rely on a certain document management software, and people who have already organized records in other tools can also use it.
How to make a literature research flow chart? One sentence conclusion
The safe way is to draw four sections of "search, deduplication, preliminary screening, and re-screening and inclusion", with one or two boxes in each section, and arrows from top to bottom. The excluded documents are placed in the side box, and the reasons and number of articles are stated. The table below explains what to do in different situations.
| your situation | Recommended practices | reason |
|---|---|---|
| Only one or two databases were searched, and there were not many documents. | Four-paragraph structure, the side box only lists "reasons for exclusion" and the number of articles | The structure is simple and readers can understand it at a glance |
| Searched multiple databases and exported multiple records | In the retrieval stage, the number of entries is listed in different databases and then merged into the deduplication box. | Can explain the contribution of each source to facilitate reproduction |
| There is gray literature (conference abstracts, dissertations, preprints) | Create a separate "Other Sources" box alongside the database search | Avoid counting together with official journal documents |
| The study is qualitative interviews or cases, not bibliometrics | It can be simplified into three sections:"search, filter, and include" | The flow chart should serve the research method and does not need to copy the template |
| The field or journal has designated reporting standards | Draw the boxes and fields required by the specification | The editor will check according to the specifications when submitting the manuscript. |
Before you start: Confirm these points first
1. Determine the inclusion and exclusion criteria first, and then draw the picture. The reasons for exclusion in the flow chart should be consistent with the standards. If the standard says "only include Chinese journal articles published after 2015", reasons such as "language incompatibility" that are not defined in the standard cannot appear in the picture.
2. Write down the raw numbers for each step. The date, database name, search query and number of items returned for each search must be saved. When drawing pictures later, copy the numbers directly from the records, do not fill them in based on impressions.
3. Determine the deduplication method. There will be a large number of duplicate documents between different databases. You can use the automatic function of literature management software to remove duplicates, or you can manually compare by title and author. No matter which method is used, the quantity after deduplication must be indicated in the deduplication box of the flow chart.
4. Distinguish between "exclusion" and "failure to obtain". Documents whose full text cannot be obtained should be classified separately and written as "Full text cannot be obtained" and should not be mixed with documents that are actively excluded. This way readers can see how stringent the screening is.
5. Reserve room for modification. Search query adjustments, supplementary searches, or review comments will cause the numbers to change. Drawing pictures using editable Markdown documents is easier to update at any time than a fixed picture.
Steps to use Markdown to draw a literature screening flow chart in UniDoc
UniDoc web editor (app.unidoc.top) supports inserting icons into Markdown documents. The following steps use a first draft of a review as an example to illustrate how to write a flowchart in the methods section.
- Open or create a new Markdown document. Create a new document after logging in at app.unidoc.top and use it as a draft method chapter of the review.
- Write a text description in the method section. First use two or three sentences to summarize the search scope and screening criteria. The flow chart is placed after this description. Readers should read the text first and then look at the picture.
- List all nodes of the flow chart. First write down the name and number of each box on paper or a document, such as "Database search (number of records)" "After deduplication (number of records)" "Initial screening of title abstract" "Full text re-screening" "Included studies", as well as the exclusion boxes on the side.
- Write nodes and arrows according to the graphic syntax supported by the editor. Insert a diagram area in Markdown and write nodes, connections and text according to the editor's syntax help. The node text should be as short as possible, and specific numbers and exclusion reasons can be written in the node name.
- Check the rendering results. Preview or switch to the rendering view and confirm that each box is displayed, the arrow direction is from top to bottom, and the side borders do not block the main process.
- Add a description below the picture. For example, state "The numbers are the number of records at each stage, and the reasons for exclusions are included according to the main reasons" to let readers know the statistical caliber.
- Save and export. After the document is saved, it can be exported to the required format as needed, with the figures and text kept in sync. If you want to convert your manuscript to Word or LaTeX before submitting, first make sure that the exported diagrams and numbers are still correct.
Check each item after completion
After completing the flow diagram, do not put it directly into the manuscript. Check the items one by one according to the table below.
| Check items | How to see it | What should you do if there's a problem? |
|---|---|---|
| Are the numbers balanced? | The number after deduplication equals the total number of searches minus the number of duplicates; The number of included cases equals the remaining number after re-screening | Return to the original record for verification to identify missed or duplicated steps |
| Excluding reasons for classification | The reason for each side frame can be found in the corresponding clause in the inclusion standard | Reasons outside the standard are removed, or the standard is modified to cover them |
| Check whether the image matches the main text | The number of articles and database names mentioned in the main text are consistent with those in the figure | Uniformly change to the same number, based on the original records |
| Check whether the search date and database are clearly stated | The chart or caption contains the search date and database name | Supplement with captions to prevent readers from reproducing them |
| Whether the text is clear | Node names should not exceed one line; without abbreviations, readers may not understand them | When an abbreviation first appears, write its full name and explain it in the caption |
If you find the numbers don't match, don't change the map yet; instead, go back to the search record and filter table to recount. If machine translation or OCR was used to process abstracts of literature, key information should also be verified, as identification or translation errors can directly affect screening results.
📊 Core Comparison
There are three common approaches to drawing literature flowcharts, each with its own focus. You can choose according to the table below.
| Method | Suitable situation | Notes |
|---|---|---|
| Hand-drawn or paper sketches | Early discussions on plans, quick changes | The official manuscript needs to be redrawn |
| General-purpose drawing software | Submission images requiring fine formatting have strong controllability | When the numbers change, modify the text inside each box one by one |
| Place the Markdown icon in the document | Frequently modifying numbers is needed, and you want the image to be saved synchronously with the main text | After exporting, check that the diagrams and numbers are still correct |
🎯 Which method suits you?
- If you're writing a draft review and you're still adjusting search and filtering, prioritize using Markdown icons, as there are fewer changes after the numbers change.
- If your journal or advisor requires a specific layout, first draw the layout according to the requirements, then verify the numbers with the Markdown version.
- If you only need a simple three-part flowchart for your course report, just sketch it on paper and draw it all at once.
❓ Frequently Asked Questions (FAQ)
1. Can records exported from literature management software be directly used to draw flowcharts?
Yes, you can. The number of exported records is the number from the retrieval phase, and the number of deduplicated records can also be calculated by the software. However, note that the software's automatic deduplication rules may not match your standards. It is recommended to randomly check a few sets of duplicates before finalizing the numbers.
2. How should the exclusion reasons in the flowchart be written to be considered standardized?
Exclusion reasons should correspond one-to-one with inclusion criteria, such as "non-target population," "study type inconsistencies," and "full text not available." After each reason, write the number of articles; the sum of multiple reasons should equal the total number of exclusions at that stage.
3. What should I do if I can't copy the scanned PDF abstract?
You can first perform OCR recognition on the scan, then manually check the title and abstract. To quickly view the full text, you can upload the PDF to OmniDoc for translation, but important content still needs to be confirmed in the original text.
4. What elements should the flowchart be consistent with?
At the very least, consistency must be with the text in the methods section, the number of papers included in the results section, and the list of references in the appendix. Whenever any digit is modified, the other positions must be checked simultaneously.
5. Can a completed Markdown flowchart be converted to Word?
You can export Word files from UniDoc, but after exporting, you should open the file to check whether the diagrams are complete and the numbers are correct. If a specific format is required for submission, after exporting, adjustments will be made according to journal requirements.
📝 Summary
The key to the literature research flowchart is to match the numbers in each box with the search records, and to keep the exclusion reasons and inclusion criteria consistent. Draw diagrams according to the structure of "search, deduplication, initial screening, re-screening and inclusion," save Markdown icons synchronously with the main text, only update the numbers when modifying, making verification easier.
