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

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  • Mohammad Teymouri October 6th, 2022 5:58 pm
    Hi,
    There is an error when I want to use the thesaurus file!
    It says, "error while reading VOSreviewer thesaurus file (line1), incorrect use of quotes.
    Thanks, Mohammad
    Reply
  • Fai August 17th, 2022 9:56 pm
    I solved it, select all options not the default when you do csv export from Scopus
    https://www.youtube.com/watch?v=azw1EEZrNI8
    Reply
  • Omwoyo Bosire Onyancha August 12th, 2022 12:32 pm
    Hi. I have a text of keywords/topics that I would like to analyse and map using the VosViewer. The topics are in the format below. When I try to analyse them, VosViewer maps words instead of a topic/phrase. I have tried to separate the words using a semi-colon but in vain. The file format is .txt.
    HIV,HIV Infections,HIV-1
    Health Literacy,Patients,Internet
    Traffic Control,Transportation,Models
    Industry,Research,Marketing
    Archives,Library,Collections
    Semantics,Models,Recommender Systems
    Agents,Game Theory,Models
    Electricity,Energy,Economics
    Electronic Health Records,Medical Informatics,Delivery Of Health Care
    Library,Librarian,Information
    Library,Librarian,Information
    Archives,Library,Collections
    Library,Librarian,Information
    Industry,Information Systems,Research
    Microfinance,Farmers,Cooperative
    Library,Librarian,Information
    Computer Crime,Network Security,Intrusion Detection
    Knowledge Management,Industry,Research
    Microfinance,Farmers,Cooperative
    Neutropenia,Granulocyte Colony-Stimulating Factor,Neutrophils
    Reply
  • taeku wang August 8th, 2022 8:45 am
    Hello, what is the difference between the keywords analysis in "bibliographic data" and the terms of Title and abstract fields in ”text data“?
    In what situation will you record each of the methods?
    thank you!
    Reply
    • Ludo Waltman August 8th, 2022 4:05 pm
      Keywords are the keywords assigned to a document by the authors and/or the database. Terms are terms extracted from the titles and abstracts of documents. Some VOSviewer users feel that keyword co-occurrence maps are more useful and informative, while others prefer term co-occurrence maps. It is therefore hard to make a general recommendation to use either keyword co-occurrence maps or term co-occurrence maps. Personally I use term co-occurrence maps much more often than keyword co-occurrence maps.
      Reply
      • taeku wang August 16th, 2022 4:11 am
        thank you for your reply.
        can you tell me why you prefer term co-occurrence maps?
        by the way, I have one more question.
        When I conducted keyword and terms co-occurrence analysis, the results were very different. some text appears largest in keyword co-occurrence, but the text did not show at all in terms co-occurrence. Do you know why that happens?
        Reply
  • Amutl July 29th, 2022 9:02 am
    Hello Prof Waltman,
    I would be extremely grateful if you could help me with the following issue:
    I exported data from Scopus by checking all the boxes for a CSV file. When I open the file in VOSviewer, however, it only displays the Co-authorship and Co-occurrence options. There is no citation, bibliographic coupling, or co-citation.
    Your response is highly valued.
    Reply
    • Fairouz August 17th, 2022 9:54 pm
      I solved it, select all options not the default when you do csv export from Scopus
      https://www.youtube.com/watch?v=azw1EEZrNI8
      Reply
  • Josie Slaathaug July 21st, 2022 11:39 pm
    Hello,
    I created a thesaurus file to replace common names with species names, and I'm having trouble getting vosviewer to read it properly. Keywords of common names are still appearing when it should be only cleaned up species names. Does anyone have advice on how to get this file to work? I simply made a two-column excel sheet and exported as a tab-delimited .txt file.
    Quick help would be much appreciated!
    Reply
  • Edi July 21st, 2022 1:19 pm
    Hello Prof Waltman,
    I would be extremely grateful if you could help me with the following issue:
    I exported data from Scopus by checking all the boxes for a CSV file. When I open the file in VOSviewer, however, it only displays the Co-authorship and Co-occurrence options. There is no citation, bibliographic coupling, or co-citation.
    Your response is highly valued.
    Reply
  • TSH July 18th, 2022 6:20 pm
    The txt or ris file extracted from WoS is not working for this version of VOSviewer(can't analysis co-occurrence or so), please fix this problem :(
    Reply
  • sani July 1st, 2022 5:03 pm
    How do we fix the import errors from EndNote X9 file to VOSviewer?
    can not find author %A or keyword %K field
    Reply
  • Rohini Gupta June 30th, 2022 4:25 pm
    Hello, I made a variety of maps yesterday and hosted them on a website through Google Drive links. The embedded maps are now all broken. When I make a new map and try to share the link through google drive, the maps do not work and I get an error that the JSON files cannot be found (even though I went through authentication). Everything was working perfectly and then stopped.
    Reply
  • Ali Hadi June 24th, 2022 4:57 pm
    Please help!
    I exported data from Scopus and ticked all the boxes to have a CSV file. However, when I import the file in VOSviewer, it only shows Co-authorship and Co-occurnance options. Citation, bibliographic coupling and co-cotation are not active.
    Reply
  • zeyu wang June 15th, 2022 5:03 am
    hi
    can we use co-citation analysis?
    currently, it is unavailable as we cannot select or click.
    it is in gray color.
    Thanks!
    Reply
  • Hasan Al-Rizzo June 11th, 2022 8:21 pm
    Is it possible to use Arabic language in this software?.
    Thaks
    Reply
  • Lubov Panchenko June 6th, 2022 1:26 pm
    I teach my student to use VOSviewer in Ukraine. Thanks!
    Reply
  • Sanober Naheed June 3rd, 2022 6:30 am
    Hi,
    I am having problem with key word mapping. Everytime it is showing error. And now even the other functions other than co authors is nor working.
    Reply
  • Patricia May 31st, 2022 10:29 pm
    Dear Ludo,
    Could you please explain a bit more about the algorithm for calculating the relevance scores? I read from previous answers that there is no documentation, but I'd like to understand better the criteria to assign this score. Essentially, if I choose to keep the 60% (or similar) of terms, it always disregards terms that are very relevant to me, such as some terms from my query.
    Conversely, if I use 100% of the terms, I need to use a long list of terms in the thesaurus file or manually unselect them, otherwise, the map is full of meaningless terms.
    I appreciate any feedback!
    Kind regards,
    Reply
  • Sristhi Singh May 27th, 2022 10:07 pm
    Hello Prof Waltman,
    I would be really grateful if you could help me with the following queries
    1) What does size of the circle on the network visualization map represents?
    2)Does the meaning of size of the circles shown on the network visualization map differs in the case of bibliographic coupling and co-citation analysis?
    2) what exactly does total link strength means in case of analysis of articles?
    4) In some cases, some items of one cluster are seen in another cluster, could u please tell what does it represent?
    Reply
  • Abraham May 26th, 2022 6:00 pm
    Hi there,
    Excellent job. Thank you.
    I have a question concerning the word "leafe" appearing in my charts. "Leaves" is a common word in my input file that doesn't appears in the chart. leafe is spacially close to leaf.
    Could you help
    Best regards
    Abraham
    Reply
  • Sona Fathi May 25th, 2022 8:20 pm
    Hello!
    Why you remove the questions were asked before 2022? I refer to them to find my problems. this causes Repetitive question.
    if it is possible email me the previous them. And I have the Repetitive question:
    how can I have screenshots of each cluster separately?
    Reply
  • Monica May 20th, 2022 10:48 am
    Hello!
    I have a question regarding the overlay visualization using the average publication year. I have publications dating from 1999 to 2022, but when I do the overlay visualization it automatically chooses a scale from 2016.5 to 2018. Ofc this is related to the fact that the number of publications in my database, increases for the latest years. I know you have an option of normalizing the years to -1 to 1, but this does not provide enough insights regarding the evolution of research over years. Have you considered adding another normalization/scale to this visualization?
    Thanks!
    Reply
  • 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
      • Andrea Denton July 11th, 2022 3:49 pm
        I have the same request. VOS Viewer has proven so valuable for working with our publication data, but making more labels viewable would really help show a more accurate picture of the collaborating institutions. Thank you!!
        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
      • Nick June 8th, 2022 4:13 am
        Hi Ludo,
        Thank you very much for your response! It was very helpful!
        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
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