Getting Started

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


Share this page

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


Mandatory fields
  • Sri Amudha Kumaresan January 13th, 2018 3:47 am
    Hello! Thank you so much for sharing this wonderful software. I'm using this software in my research for cluster analysis. I have done my work in version 1.6.4 and due to technical difficulties I have lost it. Now, I'm unable to download the same version. Can you please share me the version 1.6.4?
    • Nees Jan van Eck January 15th, 2018 9:46 am
      VOSviewer version 1.6.4 can be downloaded using the following links:
      MS Windows:
      Mac OS X:
      Other systems:
  • Theoni Paschou January 1st, 2018 5:23 pm
    Good afternoon and a happy new year,
    I saw your software applied to another literature review (Zhang, 2017) and I am also interested in it but I face some difficulties importing the data.
    Can I import them also from excel? I have the Impact factor, number of citations, year etc.
    Otherwise would you mind supporting me so to import the data from Scopus?
    I would truly appreciate your kind help.
    • Ludo Waltman January 2nd, 2018 11:45 am
      If you want to provide your own data as input to VOSviewer, this can be done using VOSviewer map and network files, which can be created using Excel. The format of these files is documented in the VOSviewer manual. When you download VOSviewer, an example of a map and a network file is included in the ZIP file that you will obtain. However, creating your own map and network files is something which requires an in-depth understanding of VOSviewer. If you have only limited experience with the software, I don't recommend to take this approach.
      If you want to use Scopus data, you need to download data using the CSV export feature in the Scopus web interface. The CSV files obtained in this way can be provided as input in the 'Create Map' wizard in VOSviewer. However, at the moment, there is a bug in the Scopus CSV export, and therefore this approach may not work. Elsevier is working on fixing the problem. An alternative could be to work with Web of Science data.
  • Ali H December 29th, 2017 2:06 pm
    Dear Friends
    When I open a CSV from scopus, most time I see error:
    Incorrect number of columns
    It's very time consuming to repair it by finding the incorrect columns. can you help?
    • Ludo Waltman December 29th, 2017 2:29 pm
      Unfortunately, there currently is a bug in the CSV export of Scopus. This is causing the problem that you mention. We are in contact about this issue with the Scopus team. They are working on fixing the problem. I hope the problem will be solved soon.
  • Marcela C December 19th, 2017 4:08 pm
    I'm using VOSviewer 1.6.6 for a bibliometric study based on records from Web of Science.
    When performing "bibliographic coupling" on documents, why do I still get results in terms of "total link strength"? Shouldn't I get a different score such as "bib. coupling"?
    Thank you
    • Ludo Waltman December 19th, 2017 10:09 pm
      In your case, 'total link strength' can be understood as the total bibliographic coupling strength. VOSviewer currently does not adjust the terminology it uses to the specific type of analysis that is carried out. In future versions of the software, we do plan to adjust the terminology used by the software to the type of analysis.
  • dennis December 4th, 2017 11:01 pm
    is writing the thesaurus the only way to clean data? because when you have thousands of keywords, writing the thesaurus is really time consuming. Maybe there is another software to assist the cleaning phase? what do you suggest?
    • Ludo Waltman December 4th, 2017 11:34 pm
      Yes, this is the only option provided by VOSviewer for cleaning your data. I don’t have specific suggestions for other software tools that you could use for this purpose. However, I do want to mention that in many cases superficial cleaning of keywords may actually be sufficient. As developer of VOSviewer, my recommendation usually is not to focus too strongly on individual keywords appearing in a map, but instead to take a more holistic perspective focusing on the overall patterns emerging from a map. If the latter approach is taken, detailed cleaning of keywords usually is not necessary, and more superficial cleaning is likely to be sufficient. Hence, I often recommend to try to be pragmatic in data cleaning.
  • Evan Sterling November 30th, 2017 5:25 pm
    The Organization unit option does not appear when I create a map from Scopus data, even though I have double-checked that the CSV files include the Affiliation column, and have tried with multiple data sets. Can you suggest any reasons this might be happening? My export includes all available Scopus fields.
    • Ludo Waltman November 30th, 2017 7:30 pm
      The option to create co-authorship maps of organizations based on Scopus data is no longer supported by VOSviewer. This option has been removed in the most recent version of the software (version 1.6.6). The reason is that Scopus (unlike Web of Science) doesn't perform any harmonization of organization names. We therefore felt that Scopus data is not sufficiently clean to create proper co-authorship maps of organizations.
  • Dlan November 8th, 2017 1:36 pm
    Hi Ludo,
    When running VOSviewer, I encountered a problem pertaining to being out of memory.
    Number of articles - 35,100
    Numbers of input txt files - 71 (web of science)
    Based on the VOSviewer Manual, I attempted to increase the memory for VOSviewer. However, I could not find the VOSviewer JAR file.
    I downloaded the zipped file of VOSviewer and unzipped it in a different folder. From this folder, I ran the exe file of VOSviewer. In this folder and in my computer, there is no VOSviewer JAR file.
    My computer has 8 GB RAM.
    I would be glad if you could help solve my problem.
    Thank you.
    • Nees Jan van Eck November 9th, 2017 2:18 pm
      The VOSviewer JAR file can be obtained using the link 'Download VOSviewer 1.6.6 for other systems' on the Download webpage.
  • Daniel October 22nd, 2017 2:42 pm
    Awesome software! Thank you for making it available to all! Is it possible to merge two databases, one extracted from Web of Science and the other from Scopus and have the data analyzed it jointly by VOSviewer?
    • Ludo Waltman October 23rd, 2017 10:34 pm
      Please see below the question by Ana on September 2nd, 2015.
  • Charis Papaevangelou October 22nd, 2017 12:59 pm
    First off, I'd like to congratulate and thank you for your amazing work!
    I have two quick questions to ask:
    1) Will it be possible in the future to change clusters/items in real-time? For example, while working with one corpus, and you decide that it's actually not that meaningful and want to remove it.
    2) Are other languages going to be supported someday? I'm interested in working with Greek, which is my first language, and VOSviewer does not currently support them, to my understanding.
    Thank you once again :)
    • Ludo Waltman October 23rd, 2017 10:32 pm
      Thanks Charis for your suggestions. Although we do not yet have concrete plans for the two points that you mention, we will keep your suggestions in mind for future versions of VOSviewer.
  • Pedro October 11th, 2017 2:23 pm
    Topic: Bibliometric data analisys based on keyword occurence.
    Is it right to say that the lines connecting the keywords on my network are a representation / description of how many time those keywords were used simultaneously?
    Could I infer more information from this lines interpretation?
    Cheers and thanks beforehand!
    • Ludo Waltman October 11th, 2017 5:56 pm
      Yes, that is correct, the strength of a line (link) indicates the number of documents in which two keywords are used together. The thickness of lines in the visualization is proportional with their strength, although it may be difficult to visually distinguish between lines with different thickness.
      • Mihaela October 15th, 2017 5:12 pm
        Regarding the difficulty to distinguish between lines. Is there any way to export these data and import into another program (excel for example) in order to sort by link strength and identify the strongest links?
        • Ludo Waltman October 15th, 2017 10:28 pm
          Yes, this can be done by saving a network in a VOSviewer network file. The 'Save' button on the 'File' tab in the action panel of VOSviewer can be used for this purpose. A VOSviewer network file is a simple plain text file that can be imported for instance into MS Excel.
  • Isabel Pinho October 2nd, 2017 12:06 pm
    In this article:
    Van Eck, N.J., & Waltman, L. (2017). Citation-based clustering of publications using CitNetExplorer and VOSviewer. Scientometrics
    In pag 1060, fig1-show 22 clusters from CiteNetExplorer
    Next, in pg 1063, fig 3- using VOSviewer to analize those 22 clusters
    How Can I do the same?
    If you please, can you give the tutorial steps to make the visualization in VOSviewer of the 22 clusters that can from CitNet Explorer?
    • Ludo Waltman October 3rd, 2017 12:03 am
      Performing an analysis similar to what is reported in this paper is not entirely trivial. It requires an extensive knowledge of VOSviewer and CitNetExplorer and also some data processing skills. As we write on p. 1065 in the paper, “the combined use of the two software tools is somewhat laborious, and preparing the input data for VOSviewer based on the clustering results provided by CitNetExplorer is not entirely straightforward”.
      Basically, you need to take the following steps:
      1. In CitNetExplorer, cluster the publications and export the clustering results. To export the clustering results, choose the option ‘Export groups – Full network’ in the ‘Groups’ menu. Also make sure to save the citation network in a publications and a citations file (using the ‘Save’ button).
      2. Based on the cluster assignments of publications as well as the citation links between publications, it is now possible to construct a citation network of clusters. This requires some data processing skills. Constructing the citation network of clusters for instance can be done using MATLAB, R, or Python.
      3. The citation network constructed in step 2 needs to be saved in a VOSviewer network file. In addition, a VOSviewer map file needs to be created, providing basic information for each of the clusters (e.g., a label and a weight, where the weight can be calculated as the number of publications belonging to the cluster). More information about map and network files is provided in the VOSviewer manual.
      4. In VOSviewer, click ‘Create’, choose ‘Create a map based on a network’, select the map and network files created in step 3, and follow the remaining steps in the ‘Create Map’ wizard.
      I hope the above explanation is helpful, but I understand that some of the steps, especially step 2, may still be quite challenging.
  • Minh Nguyen September 4th, 2017 4:23 pm
    Could you elaborate on how the relevance score is calculated in the creation of map based on text data?
  • James Qin September 1st, 2017 7:05 pm
    Is it possible to restrict the analysis to a subset of items in VOSviewer published in a specific period? If yes please let me know how to do that. Thanks!
    • Ludo Waltman September 2nd, 2017 10:37 am
      This currently is not possible. It is a feature that we hope to add in some future version of VOSviewer.
  • Khan jee August 22nd, 2017 9:03 am
    It's a nice endeavor, i appreciate as is very much helpful in research domain.
  • Armando Lenin Támara Ayús August 1st, 2017 3:03 pm
    Best regard,
    I am interested in using VOSviemer to do a literature review for my doctoral thesis. I would like to have the manual to maximize the benefits of the software.
    Thank you
  • Marcelo Dionisio July 15th, 2017 6:42 pm
    How does it work with a mendeley ris file ? I exported a file with 143 articles but could not find a way to creat a map based on the most cited words or subjects.
    • Ludo Waltman July 15th, 2017 10:17 pm
      To create a map based on a RIS file, click the 'Create' button and choose either the second ('Create a map based on bibliographic data') or the third ('Create a map based on text data') option in the first step of the 'Create Map' wizard. In the second step of the wizard, make sure to select the 'RIS' tab.
  • Patrick Kang July 12th, 2017 10:01 am
    Hi I'm new with VOSviewer I selected create a map and choosed create a map based on network data and I selected csv file and then the error came up like this "Error while reading VOSviewer network file (line 1): Item without ID."
    How can I fix it? It could be stupid question but I need to solve this problem.
    Thank you.
    • Ludo Waltman July 12th, 2017 10:27 am
      It's probably easiest to start working with data downloaded from Web of Science or Scopus rather than with your own VOSviewer network file. In the 'Create Map' wizard, you then need to choose the second or the third option (create a map based on bibliographic data or based on text data) instead of the first option (create a map based on network data).
  • Enzo July 8th, 2017 1:52 pm
    Is it possible to create a map based on bibliographic data via the command line?
    I've tried so far with the -map command but it throws an error, whereas there's no problem when opening the file manually.
    (The file I'm reading is created manually as AU - author_1 AU - author_2 ER - )
    • Ludo Waltman July 9th, 2017 12:03 am
      Creating a map based on bibliographic data (e.g., data downloaded from Web of Science, Scopus, or PubMed) via the command line is not possible. VOSviewer currently doesn't have any command line parameters to support this. The -map parameter can be used only for creating a map based on a VOSviewer map file.
  • agnes June 15th, 2017 3:20 am
    Hi, is there a glossary of terms that go with VOSviewer/ datavisualisation in general? eg "weighted", "normalised weight", "total link strength", etc
    I have found that most software/articles assume this knowledge on behalf of the user/reader
    • Ludo Waltman June 15th, 2017 8:08 am
      We don't have such a glossary for VOSviewer. In the coming months, we hope to improve and extend the documentation that is available for VOSviewer users, including a better explanation of the terminology used in the software. If you want to know more about the meaning of specific terms, then please don't hesitate to ask.
      • agnes June 19th, 2017 12:02 am
        Thanks for your reply Ludo. Great to hear there will be some updates coming soon. I have read through most of the articles referenced in the manual and not coming from a mathematical background I am having trouble understanding how things such as kernels and total link strength are developed and defined.
  • mary June 13th, 2017 11:52 am
    I just downloaded the Vosviewer from this site to visualize the co-citation of authors belong to a university. First, the one that I downloaded does not have Map Tab...the video show this tab...How?
    Second, the file that I got from Web of Science and saved as a plain text...automatically saved in Word with when I create shows ERROR ....Please help me in these two cases.
    Looking forward hearing from you
    • Ludo Waltman June 14th, 2017 1:22 am
      The video offers a first introduction into VOSviewer, but it is not entirely up to date anymore. The video was created using an earlier version of the software. This explains why the user interface looks somewhat different from the current version of the software.
      Could you please send me the file that you have downloaded from Web of Science? I will then take a look at it and I will try to give you some advice.
      • mary June 14th, 2017 7:07 am
        Thanks for the reply.
        How shall I upload the file???
        • Ludo Waltman June 14th, 2017 8:29 am
          Please send the file to me by e-mail. Thanks!
    • maryam June 17th, 2017 6:41 am
      I already emailed you Nd attached the file.
  • Roberta Salgado Gonçalves da Silva June 8th, 2017 3:22 pm
    I have imported a TXT file from Web of Science, but I´d like to know how to import it to VosViewer. I´ve tried TXT and Excel but it didn´t work.
    • Ludo Waltman June 8th, 2017 7:32 pm
      Your question is very general and therefore hard to answer. More information is needed: What is the file format of the text file that you have downloaded from Web of Science (plain text, tab-delimited, or something else)? What kind of analysis are you trying to carry out using VOSviewer? Did you use the 'Create Map' wizard, and which steps did you take in the wizard?
      • Salgado June 8th, 2017 8:17 pm
        Now I found myself. Thanks
        Create a networking
  • Robert June 7th, 2017 4:12 am
    is there a 101 guide on adding more memory to the VOS viewer software in PC and mac?
    • Ludo Waltman June 7th, 2017 10:38 am
      The best information we have available on this is provided in Section 4.3 of the VOSviewer manual. When you are using the Windows version of VOSviewer (as opposed to the Mac or JAR version), the software should already be able to access most of the memory available on your system, so in that case there most likely is not much to gain by trying to make more memory available.
      • robert June 14th, 2017 2:21 pm
        OK< in the mac (terminal) when i use the jar file, it keeps running (when calculating the relevance scores) and doesn't ever stop?
        • Ludo Waltman June 14th, 2017 2:27 pm
          Could you please send me your input file by e-mail? I will then try to take a look at it.
  • R Drijvers May 16th, 2017 1:24 pm
    I can't use Web of Science, because I don't have an account. But I can't seem to register a new account. Is there an other program I can use to load the files to VOSviewer?
    Thank you
    • R Drijvers May 16th, 2017 1:29 pm
      Never mind!
  • Eliane April 17th, 2017 7:51 pm
    I have a keyword map, but I have one doubt: what kind of counting is co-occurrence?
    The occurrences refers to the keywords of the title of the article?
    I chose the options: co-occurences and All keywords.
    • Ludo Waltman April 19th, 2017 9:46 am
      This does not refer to keywords in the title (or the abstract) of a publication. Instead it refers to keywords assigned by the authors of a publication (or perhaps by the journal in which the publication has appeared). In the case of Web of Science data, this also includes algorithmically generated keywords, the so-called KeyWords Plus. In the case of PubMed data, MeSH terms are seen as keywords.
      • David June 5th, 2017 4:18 pm
        Hi Ludo,
        So is there no way to feed article titles into VOSviewer? Is there a way to "dummy up" an RIS by placing the article titles into keywords fields?
        • Ludo Waltman June 5th, 2017 5:42 pm
          Titles and also abstracts can serve as input for VOSviewer by using the third option ('Create a map based on text data') in the 'Create Map' wizard.
  • rodney March 28th, 2017 2:23 pm
    need this
  • Devina March 9th, 2017 4:56 pm
    Are there any features for embedding a map visualisation on a webpage? Or would I need to provide a link to the map, where the user opens the map on their own desktop?
    Thank you!
    • Ludo Waltman March 9th, 2017 5:33 pm
      It is possible to make a map available online using the approach outlined in Section 4.2 of the VOSviewer manual. The map is not really embedded on a webpage (this is a feature that is currently under development), but instead a link is produced that enables users - with just a single mouse click - to download VOSviewer and to open a map .
      • Devina March 9th, 2017 5:59 pm
        Thank you for confirming Ludo! I appreciate the swift response.
  • Stephen March 8th, 2017 1:40 pm
    error while reading pubmed file' pubmed result 2.text" (line 17): file in invalid.....above this command i was getting using VOS viewer.. how to salve this... I download the data from pubmed...key word search "zika Virus" duration 2011-2016... please give some idea...
  • Steph Link February 9th, 2017 11:41 pm
    When downloading data from Scopus, do I have to extract "All available Information" or will Vosviewer also work if I only extract "Citations, abstracts, and references"?
    • Ludo Waltman February 11th, 2017 8:00 pm
      It seems that downloading only citations, abstracts, and references is sufficient when working with Scopus data in VOSviewer. In general, however, my recommendation is to download as much data as possible. From this point of view, downloading all available information seems the best approach to me.
  • Christopher Guy December 27th, 2016 9:01 pm
    I am curious the best way to load data from scopus using a mac. Any suggestions would be helpful.
    • Nees Jan van Eck December 28th, 2016 7:56 pm
      In an earlier message that I posted on October 4 (see below), I briefly explained how to download Scopus data that can be used in VOSviewer. The explanation applies to all systems, including Mac.
    • PEDRO HENRIQUE December 29th, 2016 3:11 pm
  • Pedro December 20th, 2016 6:51 pm
    WOS data-base; Co-occurence analysis; All keywords.
    Looking for the top related keywords on my database, the software found many similar keywords, where on the end they are the same, for example: "logistic regression"; "logistic regression (lr)"; "logistic-regression"; "logistic-regression model"; "logistic-regression models"; "multiple logistic-regression".
    Is there any possibility to merge those items?
    Is it possible to merge them by hands (after exporting the keywords) and input on the software for further calculations?
    • Ludo Waltman December 20th, 2016 7:49 pm
      Yes, VOSviewer provides functionality for merging these keywords. This can be done using a so-called thesaurus file. For more details, please see the VOSviewer manual. Also, when downloading VOSviewer from the Download page on the VOSviewer website, you will obtain a ZIP file that includes an example of a thesaurus file.
      • Pedro Lima December 21st, 2016 11:49 am
        Thanks! I will take a look!
  • margarida rodrigues December 12th, 2016 11:31 am
    Can you provide a manual please? if it exist in portuguese better
    thank you
    • Ludo Waltman December 12th, 2016 11:35 am
      A manual (in English) is available on this page. You have probably overlooked it.
  • Gene Major October 14th, 2016 3:40 pm
    I'm new to VOSviewer. I downloaded 1.6.5 for the Mac. I selected create a map based on bibliographic data, upload my WoS text files, but when I get to the Type of analysis screen, the Citation, Bibliographic coupling, and Co-citation options are greyed out...I can't choose them. I can only choose Co-authorship and co-occurance. Is there something I'm doing wrong or are these options not available on the Mac version?
    • Ludo Waltman October 14th, 2016 7:21 pm
      This is not a Mac issue, but most likely it has to do with the way in which you have downloaded your data from Web of Science. When downloading data from Web of Science, you need to make sure to select the Web of Science Core Collection (rather than the default ‘All Databases’ option). Also, in the ‘Send to File’ dialog box in Web of Science, you need to make sure that you choose to download all fields rather than just a subset of all fields. To do so, in the ‘Record Content’ drop-down box, you need to select ‘Full Record and Cited References’.
      • Gene Major October 14th, 2016 7:54 pm
        Thanks...I thought I had done all that, since thats the way i usually extract data out of WoS. I'll check again, though. Thanks again!
      • Gene Major October 21st, 2016 4:29 pm
        Thanks Ludo. The WoS works fine. Now I have a question on Scopus. I export the results as a CSV file. And I tried all 4 options: citation only, citation +abstract, citation+abs. + reference, All the data. When I export into VosViewer (using the Scopus option), I get an error about "incorrect number of columns" for each option I try. Is there a specific set of Scopus fields I should be downloading? Thanks
  • Ola S October 4th, 2016 1:56 am
    Dear Developers,
    I believe the interface of Scopus has changed recently and there is no way to download data like it was used to be in the past.
    • Nees Jan van Eck October 4th, 2016 1:23 pm
      The Scopus interface indeed has changed, but downloading data is still possible in the same way as it was in the past. You need to perform a search in Scopus, select the records that you want to download, and click 'CSV Export' (do not click 'Download'!). Your data will then be downloaded in a CSV file. This file can be opened in VOSviewer.
      • Ola S October 5th, 2016 4:52 pm
        Thank you for the prompt response. Apparently a user needs to set in their preferences that they want to download a CSV and say which data goes into it. After these preferences are updated, the CSV download appears as an option.
        I have a second question: is there a way to Use the data from Vosviewer to create a network in Gephi, a network that shows directionality - which journal cites more from the other. E.g. There are two journals: A and B. Articles in journal B very often cite articles from journal A, but A does not cite for B. Is there a way to represent it with arrows? (I know it is somehow represented spatially).
        • Nees Jan van Eck October 5th, 2016 10:13 pm
          Unfortunately, VOSviewer completely ignores the directionality in networks, also when saving data in a GML file, which can be used to load the data in Gephi. We plan to take into account directionality in future versions of VOSviewer, but at the moment this is not yet supported.
  • jagdish Vyas September 12th, 2016 1:22 pm
    If I want map of data in Excel File (Input) Then How to use vosviewer software
    • Ludo Waltman September 12th, 2016 3:39 pm
      Your question is too general. Please first read the book chapter available above, and then please try to formulate a more specific question. For instance, explain the type of data you have and explain what kind of visualization you would like to produce.
  • Wagner Pinheiro August 22nd, 2016 3:53 am
    I'd like to know what the difference is between the types of Analysis options "Citation" and "co-citation" . Is the " Citation" like a direct citation?
    • Nees Jan van Eck August 22nd, 2016 8:13 am
      Yes, in the case of 'citation', links between items represent direct citation links. For instance, if your items are authors, the strength of the link between two authors X and Y equals the number of citations given by author X to author Y plus the number of citations given by author Y to author X.
      On the other hand, in the case of 'co-citation', links between items represent co-citation links. For instance, if your items are cited references, the strength of the link between two cited references equals the number of publications in which the two cited references both occur.
      • Wagner Pinheiro August 22nd, 2016 12:48 pm
        Thnak you Dr. Van Eck !
  • Mehmet August 19th, 2016 6:53 pm
    I am using "map based on text data" feature of the tool. It has worked great when I have introduced raw text (abstracts or full text). What I would like to do is getting maps by introducing terms (noun phrases (NPs)) that I extracted from the same textual data with using a different tool. For example, I have been working on publications from alternative medicine and have already obtained nice clusters when relying on VOSviewer NPs. For the same text, I have extracted MeSH terms using an API provided by NHI. Now I would like to employ those MeSH terms in VOSviewer to compare it to my previous results. To this end, I have fabricated sentences like "The term is traditional Traditional Chinese Medicine. The term is obesity. The term is diabetes. " and so on. For each document I have applied this logic and used them in VOSviewer. As a result, I have been offered some term by VOSviewer and I have managed to get the map. However, when I have realized that VOSviewer failed to extract many terms which were quite obvious noun phrases. So does what I have tried make sense? Is there any suggestions?
    I hope I could explain clearly.
    Thanks in advance.
    Kindest regards,
    • Ludo Waltman August 19th, 2016 7:29 pm
      If you know which MeSH terms occur in which of your publications, you can calculate (e.g., using MATLAB, R, or Python script, or using some other software tool) for each pair of MeSH terms the number of publications in which the terms both occur. In other words, you can calculate the co-occurrence matrix of your MeSH terms. My recommendation is to take this approach and to produce a VOSviewer map file and a VOSviewer network file. The format of these files is described in the VOSviewer manual. Also, when you download VOSviewer, examples of a map and a network file are provided. After creating a map and a network file, you can choose the option ‘Create a map based on network data’ in the ‘Create Map’ wizard. You can then provide your map and network files as input to VOSviewer, and VOSviewer will produce a visualization of the co-occurrence network of your MeSH terms.
      I hope this solution is helpful to you. Please feel free to contact me if you experience any difficulties.
  • Manuel Castriotta August 9th, 2016 12:15 pm
    Document bibliographic coupling and "counting method" issues.
    Dear all,
    I am conducting an analysis of "document bibliographic coupling" with Vos 1.6.4 and I had a doubt about the "counting method" choice.
    I imagine that the example you propose when you click on (?), in order to explain the "fractional counting", refers to a co-authorship analysis. I is very clear: "if an author co-authors a document with ten other authors, each of the 10 co-authorship links has a weight of 1/10 ".
    However, when i try to translate it to document bibliographic coupling dynamics, I have some troubles in order to understand how "fractional counting" work and if this makes sense.
    Could you please help me by giving an example of the way in which the software "fractionalize" document bibliographic coupling?
    Thanks in advance for any clarification and suggestions.
    Best wishes
    • Ludo Waltman August 9th, 2016 5:13 pm
      It is fully understandable that the meaning of fractional counting in the case of bibliographic coupling is not immediately clear to you. I would like to draw your attention to a recent paper in which the distinction made in VOSviewer between full and fractional counting is explained in detail, not only for co-authorship analyses, but also for bibliographic coupling and co-citation analyses. The paper is available in the arXiv and can be found here: Please don't hesitate to post follow-up questions if things are still not entirely clear after reading the paper.
  • burcu umut zan August 3rd, 2016 2:56 pm
    Hello, I am trying to learn vosviewer. I took my data set from Wos. I use both of two programs vosviewer and citnetexplorer. I use citnetexplorer for direct citation analyse.
    Here is my problem
    At first I created a map based on bibliographic data in vosviewer, I selected type of analysis as a citation with using source unit analyse. So, I had chance to see the citation numbers of publications.
    Then I used citnet explorer for the same bibliographic data. But when I compare the citation score in two programs I recognized that some citation score of some authors are not consistent with each other.
    For example, there are 40 citations for Leydesdorf in Citnet explorer, but there are 50 citations in vosviewer.
    I could not solve the origin of my problem, where am I doing wrong?
    I will be very hapy to hear your reply.
    • Ludo Waltman August 5th, 2016 11:45 am
      This is an excellent question!
      The explanation of the differences you observe between VOSviewer and CitNetExplorer is as follows. VOSviewer shows the total number of times a publication has been cited in Web of Science, while CitNetExplorer shows the number of times a publication has been cited by other publications in your data set. This is the reason why CitNetExplorer systematically shows lower citation counts. Citations received from publications in Web of Science that are not in your data set are not counted in CitNetExplorer, while they are counted in VOSviewer.
      The idea is that in the next version of CitNetExplorer it should be possible to choose between the two ways of counting citations. So users of CitNetExplorer should be able to choose whether they want to see the total number of citations a publication has received in Web of Science or only the citations a publication has received within the data set at hand.
  • Leonardo Eljach July 12th, 2016 11:35 pm
    First of all thank you very much for making this software available for all.
    how we can export data from WoS to vosviewer for creating a map of scientific field ?.
  • Ali Abdulhay June 6th, 2016 11:15 am
    When applying "Create a map based on text data" along with WoS abstracts, is it possible to get which UT codes contain extracted terms?
    For example,
    term1 --> UT1,UT2,UT3..
    term2 --> UT1,UT5,UT12
    Kindest regards,
    • Ludo Waltman June 6th, 2016 11:29 am
      In the final step in the ‘Create Map’ wizard, a list of all selected terms is shown, offering the possibility to verify the selection of terms. In this step, you can right-click on the list of terms. This will bring up a context menu in which you can choose the option ‘Export document-term relations’. By choosing this option, you will obtain a text file that on each line contains a relation between a term and a document. The documents have numerical IDs. The document with ID 1 is the first document in your Web of Science file, the document with ID 2 is the second document in your Web of Science file, and so on. The terms also have numerical IDs. The link of these IDs with the actual terms can be obtained by choosing the option ‘Export selected terms’ in the above-mentioned context menu.
      • Ali Abdulhay June 6th, 2016 12:21 pm
        It is great!
        For my work it is not only helpful to visualize the network, but also extracting key phrases to use them in other platforms. Especially when dealing with long text such as full texts or introduction section there would be plenty of uninformative terms. By getting phrases by means of co-occurrence filtering more meaningful phrases could be accessed.
        Thank you very much!
  • Ali Abdulhay June 2nd, 2016 2:18 pm
    I have used VOSviewer to cluster scientific publications by applying their canonical
    sections such as introduction, conclusion and their citing reference titles to compare
    the results with the ones based on only abstracts. So far I have obtained good results
    especially when using noun phrases (NPs) containing more than one word. To do this, I
    have manually removed those NPs having only one word. However, it took a lot especially
    when dealing with introduction sections. At this point, I have two comments about the
    features of VOSviewer.
    1) It would be nice to have an option allowing user to retain only those terms or NPs
    having more than one word.
    2) As I know, VOSviewer uses only apache's OpenNLP. I guess this choice was made due to
    its speed. I have been using stanfordNLP for a while and I can say that when more complex
    sentences are present it is more successful than OpenNLP to parse them and extract NPs.
    However, it is slow. My suggestion is that it would be great if the user is allowed to
    load his/her NPs. In other words, I have extracted NPs using stanfordNLP in a different
    environment and using them and see the results in VOSviewer would be great.
    Kind regards,
    • Ludo Waltman June 2nd, 2016 5:16 pm
      Thanks a lot for both suggestions. This type of feedback from the VOSviewer user community is always very much appreciated. We keep track of all suggestions made by users of VOSviewer, and we take this into account when determining the priorities for new features to be added to the software.
  • BA, Axel May 31st, 2016 6:02 pm
    First of all thank you very much for making this software available for all the community. I am analyzing a large corpus of text straighforward downloaded from WoS. It might be the case that some of these files do have an abstract but don't have a title, or viceversa. I was wondering if the algorithm is able to analyze these kind of files or it rejects them. This information will be very valuable for my study.
    Yours thankfully,
    • BA, Axel May 31st, 2016 6:15 pm
      Sorry i forgot to mention on the below comentary that i am creating map based on text data and using the option title and abstract.
      • Ludo Waltman June 1st, 2016 8:49 am
        Yes, VOSviewer is able to detect whether publications do or do not have a title or abstract. For instance, if for a specific publication the abstract is missing, then for this publication only the title will be used while for other publications in your data set that do have an abstract also the abstract will be taken into account. Files won't be rejected because they include some publications that do not have a title or abstract.
  • Liz Ota May 18th, 2016 1:16 am
    First of all thank you very much for making this software available for all.
    I would like to know if there is any available material on how to interpret the outcomes of the analysis. I would also like to know if there is any tool available to analyse self-citation.
    Kind regards,
    • Nees Jan van Eck May 18th, 2016 10:12 pm
      To learn more about the interpretation of VOSviewer visualizations, it’s probably best to start with the VOSviewer book chapter mentioned above. If you have any specific questions on interpretation-related issues, then please do not hesitate to ask. I am not familiar with tools for the analysis of self-citations.
  • Valon May 12th, 2016 10:27 pm
    I want to know what is and for what need fractionalization in VOSviewer version 1.6.4. I have learned the manual and the reference that is there but I don't understand. Please explain.
    • May 13th, 2016 11:38 am
      Co-occurrence counts of items typically need to be normalized. This is done in order to correct for the fact that two items that each occur a lot in the data can naturally be expected to co-occur more frequently with each other than two items that each occur just a few times in the data. In order to obtain a useful visualization of the data, it is typically necessary to perform a correction for differences between items in their frequency of occurrence. There are many ways in which such a correction can be made. VOSviewer basically offers two ways in which it can be done, using the so-called association strength approach, which is the default choice, or alternatively, using the so-called fractionalization approach. The difference between the two approaches is quite technical (see the literature references provided in the VOSviewer manual for more details). In practice, our recommendation to VOSviewer users is to use the association strength approach by default. If this doesn't give satisfactory results, users could try out the fractionalization approach as an alternative.
  • burcu umut May 11th, 2016 8:57 am
    I would like to make a comperative abstract analysis between journals. But I wonder if the abstract of the articles are not in the english languge, will there be a problem in content analyse?
    If it is not suitable for me to do content analyse for texts in other language, are there any other which you can suggest me, to do content analyse for texts not in english langauge?
    • Nees Jan van Eck May 11th, 2016 12:59 pm
      VOSviewer supports only English-language texts. I would not recommend using VOSviewer for analyzing texts that are not in English. However, you could perhaps try to translate your non-English language texts using a tool such as Google Translate, and you could then provide the translated texts as input to VOSviewer. This may work reasonably well.
  • Gesa April 15th, 2016 12:48 pm
    Making first steps creating bibliographic maps with the VOSviewer. The program suddenly only allows "co-authorship" as type of analysis, and the other options are grey/cannot be selected anymore. I have used the same files from web of science as input before and could choose those other options, but not anymore. Downloading the data again from Web of Science, trying different combinations of Web of Science output, and even unpacking VOSviewer again does not solve the problem.
    What a pitty - I was really excited about this program and the options to support literature reviews with it. Did I miss something?
    What I am trying to do is download records from Web of Science (found via reference lists and citations of articles of interest). I download these as full records with citations, into the Tab-delimited (win) file format. I'm interested in creating a map based on citations, bibliographic couplings or co-citations. Not in co-authorships.
    • April 19th, 2016 12:45 pm
      During the past days, there has been a technical problem with the functionality of Web of Science for downloading files. The files were corrupted, and this explains the problems that you have experienced in the use of VOSviewer with Web of Science data. The problem with the download functionality of Web of Science now seems to have been fixed. So if you now download new data from Web of Science, you should no longer experience any problems in the use of VOSviewer.
      • Megan May 13th, 2016 10:39 pm
        Hello! I am having the same problem as Gesa. It seems I can only do analyses on co-authorship. I am working with Web of Science files. Is there a different approach I can use? Best, Megan
        • Ludo Waltman May 14th, 2016 12:41 pm
          On the Web of Science website, did you switch from All Databases to Web of Science Core Collection? Also, when downloading the data, did you select the cited reference data to be included? Usually this explains why people are unable to perform citation-based analyses in VOSviewer.
  • Remare January 14th, 2016 10:24 pm
    I cannot find a description of how the journal_map.txt file was generated from the PubMed Medline file in the manual or elsewhere.
    • Nees Jan van Eck January 15th, 2016 11:25 am
      The files journal_map.txt and journal_network.txt were generated based on Web of Science data, not based on PubMed data. To generate the files, a large amount of raw data was extracted from the Web of Science database. Most people have access to the Web of Science database only through its web interface and cannot extract large amounts of raw data from the database. In that case, publication records can be downloaded in text files through the Web of Science web interface, and using the downloaded Web of Science files, VOSviewer can construct journal networks similar to the network provided by the files journal_map.txt and journal_network.txt.
  • Lesya December 1st, 2015 6:00 pm
    Is there any possibility to save and/or to export the selected terms list once it has been revised ?
    • Nees Jan van Eck December 2nd, 2015 4:59 pm
      When you have a term map, the terms can be exported by saving the term map in a so-called VOSviewer map file. This is a plain text file consisting of a number of columns. The file can for instance be opened in Excel. The terms are listed in the 'label' column.
  • Ana September 2nd, 2015 9:44 pm
    the vosviewer can do an analysis of data obtained in the Web of Knowledge and Scopus together?
    • Nees Jan van Eck September 12th, 2015 6:52 pm
      Unfortunately, it is not possible to use VOSviewer for a combined analysis of Web of Science and Scopus data. Web of Science and Scopus use different data formats, and therefore there is no easy way to combine the two data sources.
      • Jane September 19th, 2016 9:29 pm
        But could we build an RIS file of information from WOS and Scopus and then run it through VOSViewer?
        • Ludo Waltman September 19th, 2016 10:09 pm
          The disadvantage of the use of RIS files is that it won't be possible to create citation-based maps, that is, maps based on direct citation relations, bibliographic coupling relations, or co-citation relations. Only term co-occurrence, keyword co-occurrence, and co-authorship maps can be created using RIS files.
  • ozrakarimi March 5th, 2015 6:20 pm
    how we can export data from scopus to vosviewer for creating an atlas about scientific products?
    • Ludo Waltman March 13th, 2015 5:40 pm
      Starting from version 1.6.0, VOSviewer is able to directly process files downloaded from Scopus.
Build on Applepie CMS by Waltman Development