Getting Started

To get started with VOSviewer, you may want to take a look at some of the sources of information listed below.

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VOSviewer manual

The VOSviewer manual provides detailed and up-to-date information on the functionality of VOSviewer. The manual can also be accessed using the Manual button in VOSviewer.

Open VOSviewer manual

 

VOSviewer book chapter

VOSviewer is discussed in detail in a recent book chapter. The chapter provides a tutorial in which the use of VOSviewer is demonstrated in a step-by-step manner. The chapter is based on VOSviewer version 1.5.5. Some of the improvements and extensions introduced in the most recent versions of VOSviewer are therefore not covered in the chapter. In addition to VOSviewer, the chapter also discusses the CitNetExplorer tool for visualizing and analyzing citation networks of publications.

Open VOSviewer book chapter

VOSviewer paper

VOSviewer was originally introduced in a paper published in Scientometrics in 2010. In the meantime, VOSviewer has been improved and extended in many ways, so the paper is not fully up-to-date anymore. However, it still provides a useful introduction into the main ideas underlying VOSviewer.

Open VOSviewer paper

AIDA bookletAIDA booklet

The AIDA booklet introduces diverse case studies on research positioning and trend identification. These case studies are relevant for PhD candidates, researchers, group leaders, and policy makers. Many of the case studies make use of VOSviewer.

Open AIDA booklet

Comments

Mandatory fields
  • Sudarsan May 13th, 2022 8:23 pm
    Good to get familiar with Vos viewer
    Reply
  • Catherine May 13th, 2022 1:08 pm
    Hello, again.
    I've been using thesaurus files containing labels that are not replaced by anything (so the labels are excluded) and labels that are replaced with other terms (for example, key enabling technology would be replaced by technology). I noticed that this results in substantially different identified noun phrases than if I were to not use a thesaurus file. In this case, is it recommended to use a thesaurus file with the way that I've been using it (is this making VOSviewer more effective in identifying relevant noun phrases?), or is it best to use it sparingly and only to replace words with another term?
    Thank you.
    Reply
    • Ludo Waltman May 14th, 2022 2:44 pm
      I tend to minimize the use of a thesaurus file. Creating such a file may take a substantial amount of time and often does not significantly affect my interpretation of a term map. While the use of a thesaurus file may significantly affect the details of a term map, in my experience the high-level picture usually doesn't change much, and my advice typically is to focus the interpretation of a term map on the high-level picture, not on the details.
      Reply
  • Catherine May 13th, 2022 12:06 pm
    Hello,
    In the Van Eck and Waltman (2011) paper, what does "distributon of (second-order) co-occurrences mean? Also, what would be the cut-off score between high and low relevance scores? For example, if I have relevance scores between 0.01 and 2.16, would high relevance scores be those above 1.00?
    Thank you.
    Reply
    • Ludo Waltman May 14th, 2022 2:25 pm
      I'm afraid we don't have proper documentation of the algorithm for calculating relevance scores, so it's hard to explain the details on the algorithm. There's no specific threshold for determining what should be considered a high relevance score. This is up to the user to decide, and it may depend on the purpose of your analysis and the data set you're working with.
      Reply
  • Sristhi May 11th, 2022 4:03 pm
    Hi,
    i have two queries:
    1) Why vos viewer doesn't show all the labels on the map? Is there a way to deal with this?
    2) How does vos viewer identifies countries of the publications? Is it the country where the authors belong? or is it the country where the article is published?
    3) Does vos viewer allows us to remove the logo of vos viewer from the visualization map?
    I would be grateful if someone could help with this.
    Reply
    • Ludo Waltman May 14th, 2022 2:34 pm
      1) This is because there often is not enough space to show all labels. VOSviewer then gives priority to the labels of items with higher weights over the labels of items with lower weights. You could try switching from 'Circles' to 'Frames' if you want to see more labels.
      2) It is the country mentioned in the affiliation of an author as reported in an article.
      3) There is no option in VOSviewer to remove the logo, but you can try to manually remove it by editing a screenshot of a VOSviewer visualization in an image editor.
      Reply
      • Sristhi May 17th, 2022 6:28 pm
        Thank you so much Mr Waltman
        Reply
  • nurit Rozolyo May 11th, 2022 11:05 am
    why don't you answer me????????????????
    Reply
  • nurit Rozolyo May 8th, 2022 10:36 am
    there are difficulties in sharing some of the maps, and I can't understand why it share one and not the other....
    for exam:
    https://tinyurl.com/y3faey3g- the link can be shared.
    https://tinyurl.com/yxq6xl63- the link can't be shared!
    I'll appreciate any clarification...
    Reply
    • Ludo Waltman May 14th, 2022 8:26 pm
      Apologies for the slow response. It took some time to investigate your problem. There turns out to be a bug in VOSviewer Online. The bug has to do with the use of double quotation marks in JSON files.
      Thanks for bringing this issue to our attention! It will be fixed in the next update of the software.
      Reply
  • Catherine May 7th, 2022 11:43 am
    Hello. I am following up on my questions: 1) While "and" is not included in the noun phrases, "&" is included. I'm wondering why that may be? 2) I was trying to send a previous message several times as it kept saying the verification expired until I got a message saying that my IP was banned due to suspicious activity. I couldn't access the website after that. I am now on a different IP and when I went to this webpage, I saw that my message had already gone through. Is there a way to clear the ban? 3) Just a note that it doesn't seem like all plural noun phrases are converted to singular. For example, "key enabling technologies" and "key enabling technology" are both in the "Verify selected terms" section of "Create map". 4) The “Share” icon doesn’t show up for me on VOSviewer Online. I’ve tried it on Chrome, Edge, and Firefox. Is there a reason I'm not allowed to share? 5) In the thesaurus file, what are the potential consequences, if any, if several terms, identified from different documents, are replaced by one term? For example, if the labels “co evolution” (from document 1), “evolutionary function” (from document 2), “cities evolf” (from document 2), and “long term evolution” (from document 3) are replaced by “evolution”, will VOSviewer then show “evolution” coming from 3 documents (for binary counting)? And how will this affect the relevance score and the clustering? Thank you!
    Reply
    • Ludo Waltman May 8th, 2022 8:58 am
      In exceptional cases the plural to singular conversion may fail. You can then use a thesaurus file to perform the conversion.
      In your example, when you use the thesaurus file, VOSviewer will indeed consider the term 'evolution' to occur in each of the three documents, leading to three occurrences of this term in the case of binary counting. The results of the next steps in the analysis, such as the calculation of relevance scores and the clustering, will be identical to the results that would have been obtained if the term 'evolution' had occurred in each of the three documents and no thesaurus file had been used.
      In VOSviewer Online, the 'Share' button appears only when you use VOSviewer Online to view a visualization that is already available online. It won't appear when you use VOSviewer Online to view a visualization that is stored locally on your computer.
      Reply
      • Catherine May 8th, 2022 12:40 pm
        Thank you!
        Reply
  • Therese Tikkanen May 2nd, 2022 11:11 am
    Hi! I'm currently using VOSviewer in my thesis and I stumbled upon a question mark. In the analysis tab I've experimented with the clustering and I can't choose if I should change the min. cluster size or the resolution to get my desired amount of clusters (around 9, to better view and describe the clusters). I'm not sure if my desired amount of clusters is a question of detail or simplicity. Does anyone have any advice in which of these modifications are better to use?
    Co-citation map based on min. cluster size (9 clusters): https://tinyurl.com/y5fjcvhr
    Same map based on resolution (9 clusters): https://tinyurl.com/y6e6zdv6
    There is a difference but I can't tell what the difference is or what it means, if that makes sense. Any help would be greatly appriceated!
    Reply
    • Therese Tikkanen May 2nd, 2022 11:27 am
      I just saw the first map has 6 clusters and not 9, excuse my confusion. I'm still curious regarding the choice between resolution and min. cluster size though!
      Reply
      • Ludo Waltman May 2nd, 2022 12:02 pm
        My advice is to rely primarily on the resolution parameter and to use the minimum cluster size parameter only to get rid of very small clusters (e.g., containing fewer than 5 items). Furthermore, my advice is to choose the parameter values in such a way that you obtain a level of granularity that fits well with the question you want to answer. For some questions you may need a high level of granularity (i.e., a relatively large number of clusters), while for other questions a low level of granularity (i.e., a relatively small number of clusters) may be more suitable.
        Reply
  • ‫נורית רוזוליו‬‎ April 29th, 2022 4:40 pm
    there are difficulties in sharing some of the maps, and I can't understand why it share one and not the other....
    for exam:
    https://tinyurl.com/y3faey3g- the link can be shared.
    https://tinyurl.com/yxq6xl63- the link can't be shared!
    I'll appreciate any clarification...
    Reply
    • nurit rozolyo May 2nd, 2022 12:14 pm
      can you please answer me?
      Reply
  • Carolina Contreras April 28th, 2022 3:30 am
    Hi!
    Can I choose how many clusters to have? Thank you!
    Reply
    • Ludo Waltman April 28th, 2022 8:00 am
      You cannot directly choose the number of clusters, but you can influence the number of clusters by changing the resolution parameter on the 'Analysis' tab. The higher the value of this parameter, the larger the number of clusters that you will get. The default value is 1.0. Typical values are between 0.5 and 2.0.
      Reply
  • Faza Fawzan Bastarianto April 25th, 2022 1:18 pm
    Hi, I am trying to open VosViewer through my MacOs. However, it failed to open every time I tried to open it as there was an error message "Unable to load Java Runtime Environment". Currently, I have installed java version "11.0.13" 2021-10-19 LTS on my Mac.
    Reply
    • Faza Fawzan Bastarianto April 28th, 2022 8:31 pm
      Hi, can someone respond to my inquiry above? thanks
      Reply
      • Farida April 29th, 2022 3:05 pm
        I had the same problem when installing you just have to download java on your mac and then try opening VOSviewer again and it should work fine.
        Reply
  • Jennifer Sharkey April 22nd, 2022 2:36 am
    Love VOSviewer and I'm currently using it in my PhD. Is there a way to save the cluster groupings into a txt file (as the keywords can be?) Thanks
    Reply
    • Ludo Waltman April 22nd, 2022 10:25 pm
      You can save your map in a VOSviewer map file (using the 'Save' button on the 'File' tab) and then open this file in a spreadsheet program. Cluster information can then be found in the 'cluster' column.
      Reply
      • Jennifer Sharkey April 23rd, 2022 1:13 am
        Brilliant thank you
        Reply
  • van anh April 20th, 2022 11:28 am
    Thank you so much
    Reply
  • Nick April 19th, 2022 9:27 am
    Hi!
    Firstly, just want to say that the programme is great and very easy to use!
    I want to check if 1) I'm manipulating a RIS file by replacing the ABSTRACT column with keywords of the article instead of abstracts and 2) use the "title and abstract" option in VOSViewer for text file for RIS, will this work normally or is the algorithm for visualizing title and abstract different from what would be used to visualize keywords.
    Thank you!
    Reply
    • Ludo Waltman April 23rd, 2022 2:50 pm
      My advice is not to take this approach. There is no guarantee that the algorithm used by VOSviewer for extracting terms from abstracts will correctly identify your keywords (although in most cases it probably will). Instead, my advice is to add your keywords in a keywords field (denoted by 'KW') in your RIS file and to use the option for creating a keyword co-occurrence map (rather than a term co-occurrence map) in VOSviewer.
      Reply
  • Erie Riza Nugraha April 16th, 2022 5:41 am
    good job...!
    Reply
  • Rumiana Koynova April 15th, 2022 11:29 pm
    Is it possible to use the online version for the initial creation of the network and map files? Or you need the installed version for that, and use the online version for further modification of the visualization?
    Thanks!
    Reply
    • Ludo Waltman April 16th, 2022 8:18 am
      You need the stand-alone version of VOSviewer to create a map and network file. VOSviewer Online can be used to present a visualization based on a map and network file, but it cannot be used to create these files.
      Reply
      • Brady Boettcher April 16th, 2022 9:33 pm
        I've seen mentions of the ability to generate map and network files from the command line using VOSviewer, but can't find this mentioned in the manual. Is this possible?
        Reply
      • Brady Boettcher April 16th, 2022 10:35 pm
        Specifically, creating maps and networks from the command line with data from JSON from an API, such as CrossRef. Similar to how Dimensions dynamically creates networks on its web platform.
        Reply
        • Ludo Waltman April 16th, 2022 11:21 pm
          The JSON file format used by VOSviewer is documented here: https://app.vosviewer.com/docs/file-types/json-file-type/. Use the 'json' parameter to create a network from the command line based on data from a JSON file. See Section 5.1 in the VOSviewer manual.
          Reply
          • Brady Boettcher April 17th, 2022 2:02 am
            Thanks for the response! For the JSON method, is it possible to have VOSviewer calculate the links, scores and positions of the items automatically like it does when using the GUI, or does the developer have to do this themselves?
            Reply
            • Ludo Waltman April 17th, 2022 7:55 am
              You need to provide the links, and optionally also the scores, as input. VOSviewer is able to calculate the positions (as well as the clusters) based on the links.
              Reply
  • Ai F April 12th, 2022 2:54 am
    Thank you for your worthy system. I have a question.
    If we create a new map of the co-occurrence of terms using the text data in the bibliographic database files, how can we obtain the correspondance between the “document IDs” listed in the file of “Document-Term Relations.txt” and the bibliographic information of the articles (e.g. PMID, etc.) ?
    Similarly, if I create a new map for the citation of documents using the bibliographic data in the bibliographic database files, could I obtain like the correspondence table of document IDs and PMID?
    Reply
    • Ludo Waltman April 12th, 2022 7:34 am
      The document with ID 1 corresponds with the first document in your bibliographic database file, the document with ID 2 corresponds with the second document in your bibliographic database file, and so on.
      Reply
      • Ai F April 13th, 2022 3:47 am
        Thank you. I understand. Let me confirm one more point.
        If the PubMed data is split into multiple files, is it correct that the IDs correspond, in order, first document, second document, ..., and last document in file 1, first document, second document, ..., and last document in file 2, and so on? Are the files read in ascending order by file name?
        Reply
  • Ali Rhouma April 10th, 2022 3:23 pm
    Dear Sor,
    I have a list of journals published by funded projects and I wanna drew a map of who is working with who (co-publications between countries for instance) and also the main keywords. Can the software use a table generated by our local platform?
    Thanks for your help
    Reply
    • Ludo Waltman April 10th, 2022 5:34 pm
      You could try to convert your data to the format of a VOSviewer map file and a VOSviewer network file. These files types are described in the VOSviewer manual.
      Reply
  • Faza Fawzan Bastarianto April 5th, 2022 12:52 pm
    Hi, I am trying to open VosViewer through my MacOs. However, it was failed to open every time I tried to open it as there was an error message "Unable to load Java Runtime Environment". Currently, I have installed java version "11.0.13" 2021-10-19 LTS on my Mac.
    Reply
  • ARUN SAXENA April 5th, 2022 4:45 am
    Hi Ludo.
    Good day to you. Could you please help with a link to a good case study that demonstrates interpretation of keyword Co-occurrence and thematic analysis in great detail with the help of an example.
    Thx.
    Reply
  • LIU CAI April 5th, 2022 4:38 am
    Hello!
    I'm having a wierd issue using VOS, 1.6.18, the windows version. When I open it and try to upload the files, the pagese get stuck as I move the mouse. For example, the "Ok" button and the "NEXT" button disappear, or appear on top of each other, or the file upload box show repeatly on one page, or the content go completely blank on one page.
    I really appreciate it if you can help me with it.
    Reply
  • Daniela Valenzuela April 4th, 2022 6:13 pm
    Hi, I am receiving the following error:
    Error while reading Lens file: Cannot find author/s, Keywords, MeSH Terms or References field.
    I am downloading data from Lens.org in CSV format. Any help? Thank you in advance.
    Reply
  • Catherine April 3rd, 2022 3:23 pm
    Hello,
    I am uploading a text file with excerpts from each document in each line. So i don't move on to the next line unless it's an excerpt from another document. I understand that by doing so, the program will read each line as a new source/document.
    I now just want to clarify the difference between full and binary counting.
    For binary, the manual states, "the Occurrences attribute indicates the number of documents in which a term occurs at least once". Does this mean that if we opt to choose terms that occur at least twice, the program would then find terms that occur in at least two documents (or lines)? Or does the program find terms that occur at least twice in a document?
    For full, the manual states "the total number of occurrences of a term in all documents". Does this mean that if we opt to choose terms that occur at least twice, the program would then find terms that occur at least twice in the entire text file (regardless of whether or not a document/line contains the word)? Or does the program find terms that occur at least twice in a document?
    Thank you.
    Reply
    • Ludo Waltman April 3rd, 2022 6:16 pm
      In the case of binary counting, VOSviewer will select all terms that occur in at least two documents (regardless of the number of times they occur in these documents). In the case of full counting, VOSviewer will select all terms that occur at least twice in the corpus, either in two different documents or two times in the same document.
      Reply
      • Catherine April 4th, 2022 3:04 am
        Thank you very much for your quick response! To further clarify, for binary counting: if we opt for 1 occurrence, then does the line between two terms demonstrate that they both occur in at least the same sentence in a document? And if we opt for 2 occurrences, then does the line between two terms demonstrate that they both occur in at least the same sentence in a document or does it mean at least two same documents? Furthermore, the thicker the line the more frequent that both terms appear together? Thank you.
        Reply
        • Ludo Waltman April 4th, 2022 7:15 am
          Co-occurrences of terms are identified at the document level, not at the sentence level. A link between two terms therefore indicates that the terms occur together in at least one document, but not necessarily in the same sentence. Indeed, the thicker the line, the larger the number of co-occurrences of two terms.
          Reply
          • Catherine April 4th, 2022 7:13 pm
            I see. So, for binary counting, if I opt for a minimum of 2 occurrences, would I be correct then in saying the following statements: "VOSviewer will select all terms that occur in at least two documents (regardless of the number of times they occur in these documents)". The more prominent a term is on the map, the more documents this term occurs in. In terms of co-occurrences, if a term is linked to another term on the map, it means that, individually, both terms occur in at least two documents (not necessarily the same documents), but they co-occur in at least one document and, the more prominent the link, the more documents they both occur in.
            Reply
            • Catherine April 5th, 2022 5:51 pm
              In addition to my last question I also have the following questions. (1) i uploaded a corpus file into VOSviewer with text from just one document. i made sure that all the text are in just one line (i use Notepad++ which shows you each line that is in use). In this case, for binary counting, obviously the only occurrence is 1. Each identified term also had a relevance score of 1.00. After generating the map, I noticed that not all terms link to all the other terms. Shouldn't they all link to each other given that they are all from the same document and VOSviewer identifies co-occurrences at the document level? (2) For the thesaurus file: a term in the label column must be a noun phrase (i.e., without a preposition) but it can be replaced by a term with a preposition? So, for example, I cannot replace "quality of life" with "QoL", but I can replace "QoL" with "quality of life"? This means that for terms such as "quality of life" and "research and development" i would have to replace them in the corpus file with noun phrases or abbreviations (such as QoL and RD) so that they show up in the map? (3) Is there a faster way to obtain a list of terms that VOSviewer identifies with a minimum of 1 occurrence without saving the map.txt file? I noticed that there are long noun phrases that I don't need, but they have short noun phrases that I do need. For example, VOSviewer identifies "artifical neural network", but i only want "network". I take it then that I would have to use the thesaurus file to replace "artifical neural network" with "network"? If so, is there a way to populate the list of terms so that I can just copy them into my thesaurus file and add the "replace by" terms for the labels that I do need, without having to generate the map in the first place? Thank you for your time in responding to our queries!
              Reply
              • Catherine April 10th, 2022 12:59 am
                Hello, I just want to say that I actually discovered the answer to my 3rd question. In the "Verify selected terms" section of the "Create map" option, if you right click on a term, a pop-up menu gives you the option to export the selected terms.
                Reply
                • Ludo Waltman April 10th, 2022 1:35 pm
                  (1) Yes, they should indeed all link to each other. Perhaps the number of links in your map exceeds the maximum number of links shown by VOSviewer? By default, VOSviewer shows a maximum of 1000 links.
                  (2) No, I'm afraid this is not possible. Prepositions will be ignored, also when you use a thesaurus file.
                  (3) Good to hear you managed to find an answer!
                  Reply
                  • Catherine April 16th, 2022 3:45 pm
                    Thank you, Ludo. I am now having an issue with the thesaurus file. After exporting the identified noun phrases (with at least 1 occurrence), I imported these into Excel (all noun phrases from several corpus files into one Excel sheet) to use them as the basis for my thesaurus file. I have over 4k labels and I added "replace by" labels for over 3k of them. The remaining labels are meant to be ignored by VOSviewer. I then saved the Excel worksheet as a tab delimited text file. However, when I use the text file into VOSviewer, some of the label-replace by pairings are flagged as errors by VOSviewer: "A label cannot be both in the label column and in the replace by column." An example is the label "rapid adoption" replaced by "adoption". After getting around 10 of these, I saved these "error" pairings as a separate thesaurus file and VOSviewer accepted them without any errors. I'm assuming then that the pairings are not the issue but something with my original thesaurus file? I thought perhaps saving it as a text file from Excel created an issue, so I copied the content from the Excel sheet into Notepad++, but this did not solve it. I'm quite stuck at this point. If it wasn't for the over 4k labels, i'd manually copy each pairing into Notepad++ (i also tried Notepad, but the same issue). Is there another way I can save the thesaurus from Excel to Notepad without VOSviewer giving an error? Or is there something to look out for when doing so that may be glitching VOSviewer into giving an error?
                    Reply
                    • Ludo Waltman April 16th, 2022 6:12 pm
                      Replacing 'rapid adoption' by 'adoption' is perfectly ok. However, VOSviewer doesn't accept a thesaurus file in which the same term occurs in both columns (not necessarily on the same line). Hence, it is not allowed to replace term A by term B and term B by term C.
                      Saving your thesaurus file as a tab-delimited text file in Excel should be fine.
                      Reply
                      • Catherine April 20th, 2022 11:38 am
                        Thank you! That was definitely what was tripping up my thesaurus file and was able to clear it up. I now notice that if "and" was replaced with "&", noun phrases like "research & development" are identified by VOSviewer. I'm wondering why that is happening?
                        Reply
                        • Catherine April 20th, 2022 11:51 am
                          Just a note: I was trying to send the above message several times as it kept saying the verification expired until I got a message saying that my IP was banned due to suspicious activity. I couldn't access the website after that. I am now on a different IP and when I went to this webpage, I saw that my message had already gone through. Does this mean I can no longer access your website with the first IP? Is there a way to clear the ban? Thank you.
                          Reply
                          • Catherine April 20th, 2022 12:02 pm
                            Also, it doesn't seem like all plural noun phrases are converted to singular. For example, "key enabling technologies" and "key enabling technology" are both in the "Verify selected terms" section of "Create map".
                            Reply
                            • Catherine April 20th, 2022 12:34 pm
                              Another note: the “Share” icon doesn’t show up for me on VOSviewer Online. I’ve tried it on Chrome, Edge, and Firefox. Is there a reason I'm not allowed to share?
                              Reply
                              • Catherine April 20th, 2022 12:50 pm
                                Apologies for so many messages: In relation to the thesaurus, what are the potential consequences, if any, if several terms, identified from different documents, are replaced by one term? For example, if the labels “co evolution” (from document 1), “evolutionary function” (from document 2), “cities evolf” (from document 2), and “long term evolution” (from document 3) are replaced by “evolution”, will VOSviewer then show “evolution” coming from 3 documents (for binary counting)? And how will this affect the relevance score and the clustering? Thank you.”
                                Reply
                  • Catherine April 16th, 2022 3:56 pm
                    For (1), just clarifying that the max links possible is 10,000? I tried going beyond that, but VOSviewer kept switching it back to 10k. Also, yes, you're right. When I went up to 10,000, I finally saw the links. Thank you for that.
                    Reply
            • Ludo Waltman April 10th, 2022 1:19 pm
              Yes, this is fully correct.
              Reply
  • mai April 1st, 2022 3:36 pm
    maixiaojunbst@gmail.com
    hello. can I ask why the co-occurrence and other choose not available only the co-author can work? the total included reference is 88, and I also update the application to the latest one. thanks for your guys answers.
    Reply
    • Ludo Waltman April 1st, 2022 10:28 pm
      The options available in VOSviewer are dependent on the type of data provided as input to VOSviewer. I am not sure what kind of data you are working with, but apparently data for co-occurrence and citation-based analyses is missing.
      Reply
  • Nurmardhiya Darnalis March 31st, 2022 3:39 am
    Hi. I have one question. What if 1 authors was from 2 countries / institutions? How was this handled in the Vosviewer?
    Reply
    • Ludo Waltman March 31st, 2022 7:32 am
      Both countries/institutions will be taken into account. In a co-authorship analysis of countries/institutions, this means the two countries/institutions will be considered to be co-authors.
      Reply
  • Zahra Fard March 26th, 2022 7:16 am
    Hello!
    I have a basic question. If we import bibliographic data files from various sources such as both web of science and scopus, does VOSviewer aggregate the references with recognition of repeated sources?
    Reply
    • Ludo Waltman March 26th, 2022 9:35 am
      I am afraid it is not possible in VOSviewer to combine data from different data sources.
      Reply
    • Catherine April 5th, 2022 4:13 pm
      Depending on how many references you have, maybe you could try combining both into one text file; just make sure that you format them the same. I had a small number of WoS references so I was able to format their biblio data as per Scopus' format (a tedious process even with just a small number of references) then add the re-formatted WoS references into your Scopus text file to upload into VOSviewer.
      Reply
  • AMRUTHA March 24th, 2022 7:47 am
    Hello, while we are working on text data using Vos viewer .we can exclude words but If one word occur in short form and other word in full form. How to add the occurrence of two words since two words are same. For example if total organic carbon occurred in 5 time & Toc(short form for total organic carbon) occurred in 10 times. How to add occurrence, if I exclude any word total time of occurrence is less and result is incorrect. Is there any way to add. Kindly help me
    Reply
    • Ludo Waltman March 25th, 2022 7:30 pm
      Not sure if I understand your question in full detail, but I think this issue can be addressed by providing a thesaurus file as input to VOSviewer. You can use this file to merge different variants of the same term. See the VOSviewer manual for more details.
      Reply
  • Amin Nasir March 24th, 2022 4:04 am
    is very good idea
    Reply
  • Rumiana Koynova March 22nd, 2022 10:23 pm
    In the Manual, sample thesaurus files are mentioned - thesaurus_terms.txt and thesaurus_authors.txt
    Where can I find these files?
    Thanks!
    Reply
    • Ludo Waltman March 23rd, 2022 10:42 am
      When you download VOSviewer from the download page on the VOSviewer website, you will obtain a ZIP file that includes the sample thesaurus files.
      Reply
  • TAEKU WANG March 18th, 2022 8:40 am
    hello,
    I am a user of the app vosviewer
    I have been using vosviewer software for more than a year, thank the developer very much.
    There is a question about the new version of the example. In the example Delineating COVID-19 and Coronavirus Research provided by the website, how is the Topic Modeling in "Using topic modeling we further characterised these four largest clusters." implemented?
    I didn't find an explanation on the usage of Topic Modeling in your website, hope to get your answer.
    thanks
    Reply
    • Ludo Waltman March 20th, 2022 8:39 pm
      Topic modeling is not supported by VOSviewer. However, there are quite a few tools available to perform topic modeling. My advice is to use one of these tools.
      Reply
  • Upendra March 4th, 2022 6:35 am
    Thank you for the software development.
    I hope you are in good health and spirit.
    I have few queries and questions.
    1- After downloading the software I couldn't run the application as it shows this error " This application requires Java Runtime Environment 1.8.0" which I am unable to download. Even the online software is not functioning properly.
    2- Secondly, I wanted to do a citation analysis of top 100 articles in a specified field; how should I proceed with it. How can I extract the data to be uploaded on the Software and in what format from the databases
    Reply
  • Apichai Wattanapisit February 27th, 2022 6:39 am
    Hello,
    On the verify selected keywords window, I found both keywords with asterisk signs (*covid-19, *sars-cov-2) and keywords without asterisk signs (e.g., covid-19, sars-cov-2). Accordingly, the summation of both occurrences (*covid-19 (n=274) + covid-19 (n=1,000)) is greater than the total number of search results (n=1,000).
    What are the difference of the keyword with and without asterisk?
    Thank you.
    Reply
  • Nadeesha February 26th, 2022 5:27 pm
    I want to export manually entered bibliographic data set to VOSviewer. which option should I select for "choose type of data"?
    Actually, I want to enter full manuscripts in proceedings also. That's why I want to do it. I want to do bibliographic data for relevant keywords only for one country.
    Reply
    • Ludo Waltman February 26th, 2022 7:24 pm
      What do you mean by a 'manually entered bibliographic data set'? You need to make sure your data set is provided as input to VOSviewer in a file format supported by the software. Which file format are you using?
      Reply
  • K Etemeadi February 23rd, 2022 4:12 pm
    Hello.
    I have a problem while importing CSV file from Scopus VOSviewer. The error is: Incorrect Number of Columns.
    Reply
    • Ludo Waltman February 23rd, 2022 6:52 pm
      Unfortunately, due to bugs on the Scopus side, CSV files exported from Scopus sometimes cause difficulties. There is no easy way to solve this problem, but it may help to include only the most essential fields in the data that you export from Scopus, and to leave out other fields.
      Reply
  • Viva February 22nd, 2022 4:55 pm
    Hello,
    Is it possible to conduct literature review using this tool?
    Thank you.
    Reply
    • viva February 22nd, 2022 4:57 pm
      or is it more about knowledge mapping?
      P.S. my first comment was not published in full
      Reply
      • Ludo Waltman February 22nd, 2022 5:53 pm
        A citation-based map of individual articles might be useful to support literature reviewing, but VOSviewer was not developed for this purpose. You may want to take a look at Aaron Tay's blog (http://musingsaboutlibrarianship.blogspot.com/) for information about other tools that can be used to support literature reviewing.
        Reply
        • Viva February 22nd, 2022 8:12 pm
          Thank you, Ludo.
          I appreciate you reply.
          Reply
  • Amrutha February 22nd, 2022 8:08 am
    Hello,
    I am unable to do co-occurrence in vos viewer installed in system. It is showing only bibilographi coupling ,co-citation etc but it is not showing co -occurrence.That is, there is no option for co-occurrence but I want to do occurrence .Is there any way to do co-occurrence.please help
    Thanks
    Reply
    • Ludo Waltman February 22nd, 2022 9:10 am
      In the 'Create Map' wizard, consider using the option 'Create a map based on text data' instead of 'Create a map based on bibliographic data'.
      Reply
  • Jaymes Rombaoa February 20th, 2022 9:09 pm
    Hello there!
    I'm trying to import about 36,000 Web of Science records (over 70 .txt files) for a bibliographic coupling project.
    I currently get the "Out of memory. VOSviewer will be terminated. Please refer to the VOSviewer manual to increases the availability of memory."
    I'm currently on VOsviewer version 1.6.18; I'm also using a MacBook Pro 2020 (MacOS Monterey) with Memory = 8 GB.
    I consulted the Manual, but I'm not entirely sure on the steps or what exactly to do to increase the availability of memory. Also I'm not sure on how to run the VOSviewer from the command line and enter those commands.
    Any help or step-by-step guide would be so appreciated!
    With gratitude,
    Jaymes
    Reply
    • Ludo Waltman February 21st, 2022 10:19 pm
      In the About dialog box in VOSviewer, you can see the amount of memory to which VOSviewer has access. If VOSviewer already has access to most memory in your computer, it won't be possible to increase the amount of memory that VOSviewer can use. Otherwise you could indeed follow the steps discussed in the manual to increase the amount of memory that can be used by VOSviewer. However, I am afraid I cannot offer further help with this. My advice is to ask for help from a local ICT expert who knows how to work with the command line.
      Reply
  • Beatriz Murer February 20th, 2022 8:35 pm
    Hello,
    I hope this message finds you well. Thank you for the software development. It is very helpful!
    I would like to check three information:
    (I) Is there a default clustering algorithm? I ask this because I am generating a VOSViewer network view from the Bibliometrix R package and no matter which algorithm I use in the R networkPlot function, the same network (with the same clusters) is generated in VOSViewer (when the clusterization should be different depending on the algorithm entered);
    (II) Is there a maximum amount of nodes entered in a network view in VOSViewer? I ask this because when I try to open a large network (more than 50000 nodes) in VOSViewer from the Bibliometrix R package using the "net2VOSviewer" function (https://github.com/massimoaria/bibliometrix/blob/master/R/net2VOSviewer.R), I get the error: "Error reading Pajek network file: Incorrect use of quotes". And the error does not appear when the amount of nodes is smaller;
    (III) Is the maximum view of the links (connection between nodes) really 10000? Because I have a network with more than 300000 links, and it would be very useful to see all their connections in VOSViewer.
    Thank you very much.
    Best regards,
    Reply
    • Ludo Waltman February 21st, 2022 9:35 pm
      VOSviewer is not intended for visualizing very large networks. Other tools, such as Gephi, are more suitable for this. We recommend to have at most 10000 items in your network. Your network may consists of more than 10000 links between items, but the maximum number of links that can be visualized by VOSviewer is 10000. I am afraid I don't understand your first question. The VOSviewer manual provides some information about the clustering technique used by VOSviewer, including a link to the relevant research papers.
      Reply
      • Beatriz Murer February 22nd, 2022 1:36 am
        Thank you very much for your quick answer, Ludo!
        In my first question I was referring to clustering algorithms such as "optimal","edge betweenness", "louvain", "infomap", "walktrap", "spinglass", "leading eigen", etc - which indicates the type of cluster (agregation between the publications).
        I haven't found this specification explicitly at VOSviewer manual, which is why I asked here. What I did find was the indication of using an "optimization algorithm" and the linked research papers - which indicate the Newman algorithm. So I'm still not sure if VOSviewer uses the optimal algorithm, Newman's algorithm, or any other. I'm sorry if it's still unclear. Once again, thank you!
        Reply
        • Ludo Waltman February 22nd, 2022 7:25 am
          The clustering technique used by VOSviewer is documented in the following paper: https://doi.org/10.1016/j.joi.2010.07.002 (preprint: https://arxiv.org/abs/1006.1032). To optimize the quality function of this clustering technique, VOSviewer uses the Leiden algorithm, documented in the following paper: https://doi.org/10.1038/s41598-019-41695-z.
          Reply
          • Beatriz Murer May 11th, 2022 5:45 am
            Hello again, Ludo!
            I really appreciate your last return.
            What I would like to ask now is still related to clustering algorithms, as you are more aware about it and perhaps could help me.
            I am looking for a community detection algorithm, which made me decide for louvain (multilevel - based on https://www.nature.com/articles/srep30750) - as this is the recommendation to big and mixed networks, as mine. But in your last answer, you brought to light the improvment from louvain to leiden (https://www.nature.com/articles/s41598-019-41695-z). Therefore, I would like to use this means of communication to ask you if you would have any reservations about using louvain to detect communities in big and mixed networks - and considering that the visualization is just an extra in my objective and that the network analysis (mainly the description of the communities/modules/clusters) is more important.
            Thanks once more!
            Best,
            Reply
  • Vivi February 20th, 2022 5:13 pm
    Hi Ludo, one more doubt please :)
    In order to choose the best clusters agroupation for co-occurrence Keywords, the words included in a Density Visualization hot point, should be almost the same than cluster agroupation? Or is not something which I have to reffered to. I read papers that show the simmilarities between both maps and others which analysed both maps separatly. Thank you so much!
    Reply
    • Ludo Waltman February 21st, 2022 9:24 pm
      I am not sure whether I understand you correctly, but choices regarding the clustering of keywords shouldn't depend on what is shown in the density visualization. These two things have nothing to do with each other.
      Reply
      • Vivi February 22nd, 2022 1:34 am
        Thank you Ludo!
        Reply
  • Varun Chandra February 17th, 2022 11:29 pm
    Hi Ludo. What does a bibliographic coupling by country map represent? What do the links between the country nodes represent?
    Reply
    • Ludo Waltman February 18th, 2022 8:25 am
      The links represent publications from different countries citing the same earlier work.
      Reply
      • Varun Chandra February 25th, 2022 1:21 am
        Ok, thanks. I also noticed in the left sidebar that under the "items" tab, there is a list of all countries involved, and if I click on one, it will show the number of documents at the bottom, along with link strength, and number of links. What does this number of documents represent? Is it the number of documents originating from that country?
        Reply
        • Ludo Waltman February 25th, 2022 8:02 am
          Yes, it is.
          Reply
  • Joseph February 15th, 2022 1:45 pm
    Hi Ludo, one more question please! I created a map based on bibliographic coupling/co-occurrence/all keywords and full counting. Could you please explain based on what the clusters are formed? I have a word with occurrence only 3 and total link strength of 34 and it’s in cluster 1.
    Thanks heaps!
    Reply
    • Ludo Waltman February 16th, 2022 8:48 pm
      I'm afraid I don't fully understand your question. Creating a map of keywords based on bibliographic coupling is not possible in VOSviewer.
      Reply
      • Joseph February 17th, 2022 5:14 am
        Hi Ludo
        Here are the steps that I chose to create the map:
        1-Create a map based on bibliographic data
        2-read data from bibliographic database files
        3-upload Scopus CSV file in the correct section
        4-chose co-occurrence / unit of analysis: all keywords / counting model: full counting
        5-occurrence of keyword adjusted to 3
        6- then clicked next and finished
        My question is related to the clusters obtained after following the above steps. Based on what are these words distributed to the relevant clusters?
        Thanks and sorry for the confusion!
        Reply
        • Ludo Waltman February 18th, 2022 8:30 am
          Thanks for the clarification, Joseph. Clusters represent groups of keywords that are relatively strongly connected to each other based on co-occurrence links, or in other words, groups of keywords that occur together in the same documents relatively often.
          Reply
  • Gabriel Oliveira February 14th, 2022 11:41 pm
    Boa noite, eu tive um problema enquanto tentava carregar um arquivo .txt que exportei da Web of Science, contudo, o programa apenas me mostra uma mensagem de erro de que arquivo é inválido devido a um problema não especificado na primeira linha.
    E não, o arquivo .txt não foi editado antes de inseri-lo no programa.
    Como eu posso resolver esse problema?
    Reply
  • Viviana February 14th, 2022 12:09 pm
    Hi Ludo, hope you are ok! Perhaps it's an ovbious question, sorry for that. In regarding KW co-ocurrence, I have some difference between cluster agroupation and density visualization hot points, are supposed to show the same groups of words? I imagine that should be simmilar since both are indicating an association between KW, is that correct?
    Reply
  • Ken Mwathe February 12th, 2022 11:17 am
    I want to analyse national policy documents to determine the extent to which they support biodiversity conservation in agriculture in Kenya. Does Vosviewer support using PDF databases of national and county government policies, strategies and plans?
    Thanks, Ken
    Reply
    • Ludo Waltman February 12th, 2022 3:47 pm
      No, I'm afraid this is not supported.
      Reply
  • Joseph Guirguis February 10th, 2022 12:01 am
    Hi team,
    Is there a way to export clusters after bibliometric analysis to an excel sheet? Thanks for your help and great job on designing Vosviewer!
    Reply
    • Ludo Waltman February 10th, 2022 7:29 am
      Yes, you can save your map in a VOSviewer map file and open this file in a spreadsheet program such as MS Excel. Cluster information can be found in the 'cluster' column.
      Reply
      • Joseph February 10th, 2022 7:37 am
        Amazing! Thanks team for your prompt response.
        Reply
  • Mahdi Zeynali February 9th, 2022 2:12 pm
    Dear Nees Jan and Ludo
    Appreciate you very much for carefully designing the necessary VOSviewer software. This used software was designed user-friendly and usability way. I watched some published videos and read some articles and book chapters about that. In this way, I sufficiently learned key application of it.
    All the best, Mahdi.
    Reply
  • Vivi February 9th, 2022 11:20 am
    Good morning Ludo, hope you are ok! I wonder if it is possible to make an overlapping map comparing countries keywords. In this case, there is any document which explain how to do it? Thank you!
    Reply
    • Ludo Waltman February 10th, 2022 8:37 am
      Do you mean you want to create a keyword co-occurrence network (or perhaps a network of co-occurrences of terms extracted from titles and abstract) and show a so-called overlay visualization in which colors are used to highlight the focal topics of different countries?
      Reply
      • Vivi February 10th, 2022 9:05 am
        Thank you Ludo for your reply.
        Exactly! I want to create a keyword co-occurrence network and show an overlay visualization and highlight the focal topics of different countries. Is that possible? In this case, there is any document I could read to understand how to do it?
        Reply
        • Ludo Waltman February 11th, 2022 5:52 pm
          For keyword co-occurrence maps there is no easy way to do this, but for co-occurrence maps of terms extracted from titles and abstracts this is possible. You can then make use of corpus and scores files. If you're interested, feel free to contact me by email. I can then give a bit more information.
          Reply
  • James Phillips February 8th, 2022 11:14 pm
    Ludo:
    The innovative work of your team might attract resources from the philanthropic arm of Google: "The Google Foundation." The problems that you note in your response to my query about Google Scholar might be solvable if you had resources to collaborate with Google itself. The humanitarian value of VOS-Viewer is amply demonstrated by publications that have used your tool for health research. Jim Phillips
    Reply
  • James Phillips February 7th, 2022 4:56 am
    A common challenge that I face is not with the use of VOS-Viewer, but rather with the preparation of data for input to your software. The data archive SCOPUS has the advantage of representing citation key words that are human reviewed. And, SCOPUS output is VOS compatible. But, the coverage of SCOPUS can be incomplete. I would like to work with Google Scholar which has massive coverage. Unfortunately, accessing and using Google Scholar output is problematic apart from its immediate display of individual citations. There is no feasible means of utilizing Google Scholar search display output as VOS Viewer input. Correct? Do you have web searching and data compilation tools advice to impart?
    Reply
    • Ludo Waltman February 7th, 2022 9:20 am
      Indeed the use of Google Scholar data in VOSviewer is almost impossible. It is very difficult to extract significant amounts of data from Google Scholar. VOSviewer used to provide support for working with Microsoft Academic data, which could serve as an alternative to Google Scholar. However, Microsoft Academic was discontinued at the end of last year. The most recent version of VOSviewer offers support for OpenAlex, a successor of Microsoft Academic. VOSviewer enables users to query OpenAlex through its API. However, this functionality is still in an early stage of development, so the possibilities are limited. Dimensions might be another alternative to Scopus. VOSviewer offers quite extensive support for working with Dimensions data, similar to what we offer for Scopus.
      Reply
  • Eka Hartomy February 2nd, 2022 1:34 pm
    Excuse me, I have a question
    I want to do co-occurence analysis in VOSViewer, but I can't choose the option. How do I solve this problem?
    Thank you
    Reply
    • Ludo Waltman February 2nd, 2022 7:25 pm
      If you want to do a co-occurrence analysis of terms extracted from titles and abstracts of publications, make sure to choose the option 'Create a map based on text data' instead of 'Create a map based on bibliographic data'. If you want to do a co-occurrence analysis of the keywords of publications, the availability of this option depends on the data source you are using. Some data sources support this option, while others do not.
      Reply
      • Eka Hartomy February 3rd, 2022 11:15 am
        In my case, I exported .ris and.csv files from dimensions.ai.
        Do you know what the problem is?
        Reply
        • Ludo Waltman February 5th, 2022 6:28 pm
          Dimensions has a special export feature for VOSviewer. Make sure to use this feature. Don't use the RIS format. Dimensions doesn't have keywords for publications, so Dimensions data cannot be used to create a co-occurrence map of keywords. You can use Dimensions data to create a co-occurrence map of terms extracted from titles and abstracts of publications.
          Reply
          • Eka Hartomy February 6th, 2022 11:23 pm
            It worked! Thank you very much Ludo, hopefully we can discuss another research-related topics again
            Reply
    • Viviana February 2nd, 2022 7:47 pm
      Hi Ludo, thank you so much for you continuing help! Relates to this question I have a doubt which I couldn't find or totally understand from the manual. A higher resolution number means more specidicy? I tried many different combinations of resolution number, min cluster ítems, as well as co-ocurrence umbral for keywords. Finally I got to a result which convince me, but I have above doubt since with different number of resolution (3 and 5) and the same min cluster ítems (6), I got to the same number of cluster which has different word compossition. So, I'm not sure which I have to choose, both has sence. I wonder if (for this example) 5 means more specificity than 3. Than you one again for your help and disign this favulouse tool.
      Reply
      • Ludo Waltman February 2nd, 2022 7:55 pm
        It's a bit hard for me to answer your question without seeing the actual results you get. Moreover, I'm not sure what you mean by the values of 3 and 5. Are these values of the resolution parameter? Such values are rather high. Normally the value of the resolution parameter shouldn't be higher than 2.
        Reply
        • Viviana February 2nd, 2022 8:17 pm
          Oh really!? I tried many diferent ones as the manual suggested "We recommend to try out different values for the Resolution parameter and to use the value that yields the most appropriate level of detail for one’s
          purposes." So, as I understand now is better yo use the default resolution number? (1). Thank you do much!
          Reply
          • Ludo Waltman February 2nd, 2022 11:45 pm
            I don't recommend to simply use the default value of 1. I believe trying out different values is important. Values above 2 are uncommon, but as already mentioned, it's hard for me to comment on your results without actually seeing them.
            Reply
            • Viviana February 3rd, 2022 4:12 am
              Thank you Ludo!
              Reply
              • Viviana February 3rd, 2022 12:45 pm
                Good day Ludo, could you please confirm to me if there is an "upper limit number" for min items cluster? On other hand, in your reply to Eka, you mention that "If you want to do a co-occurrence analysis of the keywords of publications, the availability of this option depends on the data source you are using. Some data sources support this option, while others do not." I constructed my data base with different data sources, and I think it's working well, there is something which I have to look to find that something is not working so well? Thank you so much and sorry for bother you!
                Reply
                • Ludo Waltman February 5th, 2022 6:33 pm
                  Not sure if I fully understand your question, but in principle there is no upper limit.
                  Reply
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