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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  • Cesar França October 30th, 2020 5:38 pm
    Hi! I am trying to use the data available at Semantic Scholar but could not find how to retrieve it as a DOI file.
    It seems I must use and Semantic API but I was not able to find the details of how to proceed.
    Would you mind to give me some guidance?
    Thanks,
    Cesar
    Reply
  • Liza October 30th, 2020 6:09 am
    Good day
    I am doing a term co-occurrences map based on text data. I am confused about how the link strength is calculated. The occurrence of word A is 35 and the occurrence of word B is 16, and their total link strength is 72. I thought the link is the number of times the two words co-occurred, but word A cannot co-occur with word B 72 times because it only occurred 35 times, and word B only occurred 16 times. I am using full counting
    If you can please assist on how the total link strength is calculated, please.
    Reply
  • Tejas Adsul October 28th, 2020 12:30 am
    Hi! I'm wondering if there is a way to extract the distance between the concepts from the co-occurrence map of a text-based data. Since VOSviewer is supposed to give distance-based graphs, I'd like to have a scale based on which I can tell the relative distance between two concepts. Thank you!
    Reply
  • Phuong Nguyen October 25th, 2020 5:22 pm
    Hello, i am trying out the newest version 1.6.15, but i find out that it is now missing the choice of analyze the data by citation and co-citation. Is that any way i can active it? Or do i need to find the older version of this app to have those choice?
    Reply
  • maryam vizheh October 25th, 2020 10:22 am
    Hello. I have an important question. When we formulate a search strategy whatever very precise, it is likely that so many articles will enter to our search results that they are not related to our topic. In the systematic review we assess every single abstract and title, however when we want to work with VOS VIEWER how we can be sure that all included results are exactly related to our purpose of the study? Please guide me. Thank you
    Reply
  • maryam vi October 25th, 2020 10:16 am
    Hello. I have an important question. When we formulate a search strategy whatever very precise, it is likely that so many articles will enter to our search results that they are not related to our topic. In the systematic review we assess every single abstract and title, however when we want to work with VOS VIEWER how we can be sure that all included results are exactly related to our purpose of the study? Please guide me. Thank you
    Reply
  • Liza October 19th, 2020 2:58 pm
    Good day
    I am doing a term co-occurrences map based on text data. I am confused about how the link strength is calculated. The occurrence of word A is 35 and the occurrence of word B is 16, and their total link strength is 72. I thought the link is the number of times the two words co-occurred, but word A cannot co-occur with word B 72 times because it only occurred 35 times, and word B only occurred 16 times.
    If someone can please assist on how the total link strength is calculated, please.
    Reply
    • Ludo Waltman October 19th, 2020 4:04 pm
      Did you use binary counting or full counting?
      Reply
      • Liza October 26th, 2020 9:10 am
        full counting
        Reply
  • New October 19th, 2020 11:47 am
    Hello,
    How can I combine two similar keywords?
    For example, there are
    absorptive capacity
    absorptive-capacity
    It is definitely one term.
    thank you
    Reply
    • Ludo Waltman October 19th, 2020 3:08 pm
      A thesaurus file can be used for this. Please see the VOSviewer manual for more information about thesaurus files.
      Reply
      • New October 19th, 2020 5:49 pm
        Thank you.
        Do we construct thesaurus file ourselves?
        In the manual it is written:
        "For examples of thesaurus files, see the files thesaurus_authors.txt and thesaurus_terms.txt".
        I do not understand how to obtain them.
        Reply
        • Ludo Waltman October 19th, 2020 9:47 pm
          You need to create thesaurus files yourselves. The thesaurus files that you mention are included when you download VOSviewer from https://www.vosviewer.com/download. However, these files just serve as examples.
          Reply
          • New October 21st, 2020 5:03 pm
            Thank you.
            Reply
  • Mireia Tintoré October 16th, 2020 11:40 am
    Dear authors,
    How can I provide a RefWorks file as input to VOSviewer? Thank you very much,
    Mireia
    Reply
    • Ludo Waltman October 19th, 2020 4:01 pm
      Yes, RefWorks files are supported (even though they offer only limited possibilities). You need to click the 'Create' button in VOSviewer, you then need to choose the option 'Create a map based on bibliographic data' or 'Create a map based on text data', followed by the option 'Read data from reference manager files', and you then need to go to the 'RefWorks' tab.
      Reply
      • Mireia Tintoré October 21st, 2020 5:08 pm
        Thank you
        Reply
  • Bénédicte Madon October 15th, 2020 5:51 pm
    Dear Dr Waltman,
    is there a limited number of files (e.g. in plain text) that can be selected to do the mapping?
    Best wishes
    Bénédicte
    Reply
    • Ludo Waltman October 17th, 2020 12:23 am
      When creating a map based on data from, for instance, Web of Science, Scopus, or Dimensions, it is possible to select multiple files at the same time (using the Control key). VOSviewer will then process all selected files. You don't need to manually merge your files before providing them as input to VOSviewer.
      Reply
  • Yunjin October 13th, 2020 6:53 pm
    Hi,
    I'm trying to merge the search results from multiple sources including WOS, Scopus, and pubmed.
    I was wondering if there is any available format for this or code to merge files.
    Thanks,
    Yunjin
    Reply
    • Ludo Waltman October 17th, 2020 12:15 am
      Unfortunately there is no easy way in which this can be done.
      Reply
    • Aynul October 18th, 2020 6:25 pm
      I was also looking for this but unfortunately nothing is found helpful
      Reply
  • don kirkendall October 9th, 2020 6:28 pm
    Just learned about VOSviewer today. Use a Mac, OS Catalina (10.15.1). Downloaded and extracted the zip file. When i click on VOSviewer.app, this window pops up:
    “VOSviewer.app” can’t be opened because Apple cannot check it for malicious software.
    This software needs to be updated. Contact the developer for more information."
    Any suggestions on how to proceed?
    Reply
    • don kirkendall October 9th, 2020 7:13 pm
      Success. I have been able to open the VOSviewer. Restarting my computer was the step I was missing.
      Reply
      • Anita October 11th, 2020 5:49 pm
        How did you solve your problem? I am facing the same
        Reply
  • Christian Jehle October 8th, 2020 6:13 pm
    Hi there,
    On my new Windows system VOSviewer doesn't start, saying "This applicatiopn requires a Java Runtime Environment 1.8.0".
    Actually, I've installed AdoptOpenJDK with JAVA_HOME and Path variables set properly.
    Is there any convenient way to go on without the Oracle Java RE?
    Best,
    Christian
    ---
    F:>java -version
    openjdk version "11.0.8" 2020-07-14
    OpenJDK Runtime Environment AdoptOpenJDK (build 11.0.8+10)
    OpenJDK 64-Bit Server VM AdoptOpenJDK (build 11.0.8+10, mixed mode)
    Reply
    • Christian Jehle October 14th, 2020 2:38 pm
      Ok, just found out:
      "VOSviewer 1.6.15 for other systems" works fine. To start the programme use java -jar VOSviewer.jar (for example in a *.bat file)
      Best,
      Christian
      Reply
  • Christian Jehle October 8th, 2020 6:10 pm
    Hi there,
    On my new Windows system VOSviewer doesn't start, saying "This applicatiopn requires a Java Runtime Environment 1.8.0".
    Actually, I've installed AdoptOpenJDK with JAVA_HOME and Path variables set properly.
    Is there any convenient way to go on without the Oracle Java RE?
    Best,
    Christian
    ---
    F:>java -version
    openjdk version "11.0.8" 2020-07-14
    OpenJDK Runtime Environment AdoptOpenJDK (build 11.0.8+10)
    OpenJDK 64-Bit Server VM AdoptOpenJDK (build 11.0.8+10, mixed mode)
    Reply
  • Aynul September 30th, 2020 7:17 pm
    Within a selected dataset, how can I find:
    which documents are co-cited and they are co-cited by which other documents so that I can find their co-citation number too. Waiting for your reply.
    Reply
  • Andy Yeung September 30th, 2020 4:21 am
    Hi Professor Waltman,
    Currently the output data contains average citations (per publication) for the analyzed "terms", authors, countries, journals, etc. How can we find out and report the standard deviation (SD) or the median? Thank you.
    Best regards,
    Andy
    Reply
    • Ludo Waltman October 11th, 2020 5:45 pm
      I am afraid VOSviewer doesn't support the standard deviation and the median. It is not possible in VOSviewer to obtain this information.
      Reply
  • Mostafa September 25th, 2020 7:56 am
    Hi,
    I am Mostafa from Monash university. In keywords co-occurrence analysis, in order to make the mapping more meaningful and consistent I have unified the keywords to reflect their associated concept. But there are keywords which don't really convey a concept/topic in my bibliometric analysis. I am wondering if deselection of these keywords may affect the authenticity and correctness of the analyses in VOSviewer?
    Thanks,
    Kind regards.
    Reply
    • Ludo Waltman September 25th, 2020 7:59 pm
      From my point of view, leaving out specific keywords is perfectly fine. Of course, when you report your analysis, you need to explain and justify your choice to leave out certain keywords.
      Reply
      • Mostafa September 27th, 2020 6:43 am
        Thanks for the reply. Yes I have justified the reason why I have deselected them both in the body of the review paper and the supplementary information file.
        Again, well-done on your great job and keep up your good works.
        Best wishes.
        Mostafa.
        Reply
  • Mostafa September 25th, 2020 7:49 am
    Hi,
    I am Mostafa from Monash university. In keywords co-occurrence analysis, in order to make the mapping more meaningful and consistent I have unified the keywords to reflect their associated concept. But there are keywords which don't really convey a concept/topic in my bibliometric analysis. I am wondering if deselection of these keywords may affect the authenticity and correctness of the analyses in VOSviewer?
    Thanks,
    Kind regards.
    Reply
  • Andy Yeung September 15th, 2020 8:51 am
    Dear Professor Waltman,
    Would future versions of VOSviewer consider data slicing? It will be much more convenient if we can slice the whole dataset into different time periods, or different publication types, etc. Especially when the dataset is large, it is time-consuming to re-download from WoS based on different filters. Thank you for your consideration.
    Best regards,
    Andy
    Reply
    • Ludo Waltman September 16th, 2020 9:19 am
      Thanks Andy for this suggestion. This is indeed on our to-do list, although I cannot promise we will be able to implement this in the near future. Please note that there are various data sources, such as Microsoft Academic, which VOSviewer accesses through their API (rather than by processing text files downloaded manually through a web interface). For these data sources VOSviewer already offers possibilities for data slicing.
      Reply
      • Andy Yeung September 16th, 2020 4:14 pm
        Thanks for the suggestion!
        Reply
  • Javier Guerrero September 11th, 2020 7:20 pm

    Hi,
    I have two data sets from scopus, publications in a two different journals in the same field. I'm trying to create a co-authorship network and I stumble in a little issue, same author with different name format. I have for example 'Adelekan M' in one data set and Adelekan M.L. in the other one (same author ID), and therefore producing each one a different co-authorship network. But if I try to modify the .cvs file, deleting or adding a character I get the:
    I0Exception reading next record: java.io.I0Exception: (line 2) invalid char between encapsulated token and delimeter
    any advice on how to get around this?
    cheers,
    Javier
    Reply
    • Ludo Waltman September 11th, 2020 8:02 pm
      Modifying Scopus CSV files is possible in principle, but usually causes all kinds of problems in practice. There is an easier solution to your problem, which is to use a so-called thesaurus file. See the VOSviewer manual for more information about thesaurus files.
      Reply
      • Javier Guerrero September 11th, 2020 8:42 pm

        Many thanks! will do
        Best
        Javier
        Reply
  • Oak September 9th, 2020 12:15 pm
    I am new to VOSViewer and my attempts to download it on to my pc has not been successful. I am using a Mac running on MacOS Catalina.
    I've followed Nees' guide on how to install it but it is still not working. Any assistance, please?
    Reply
  • Javier Guerrero September 7th, 2020 7:12 pm

    Hi, I try to combine two .cvs extracted from scopus, each one works fine, but as soon as I combine I get the I0Exception reading next record: java.io.I0Exception: (line 2) invalid char between encapsulated token and delimeter
    I have tried with really simple searches and complex ones, and each file works fine, but as soon as I try to merge two of them the error pops up.
    Thanks,
    Javier
    Reply
    • Ludo Waltman September 7th, 2020 7:16 pm
      VOSviewer is able to open multiple Scopus CSV files at the same time (use the Control key to select multiple files), so there is no need to manually merge your files.
      Reply
      • Javier Guerrero September 7th, 2020 7:33 pm

        Thanks :)
        Reply
  • Irene Garcia August 29th, 2020 1:57 pm
    Hi!
    I would like to know if the program allows to create a network with the data from two different databases.
    For example: to create a network about the kyewords/terms from WoS and Scopus in the same graphic. Is it possible? I have checked the manual and the tutorial video and I could not find this information.
    I really apreciate your help and time.
    Kind regards,
    Reply
    • Ludo Waltman August 29th, 2020 7:03 pm
      VOSviewer doesn't provide support for combining data from multiple data sources.
      Reply
  • Pavitra Dhamija August 24th, 2020 12:42 pm
    Dear Prof. Nees and Prof. Ludo
    Good Day ! I have recently started working on VOSviewer and just loving it.
    However, I am facing a problem that; all of the types of analysis are not enabled in the software in my system.
    For example:
    Co-authorship; Co-occurrence are enabled
    Citation; Bibliographic coupling; Co-citation are not enabled. I cannot use these three types.
    Kindly extend your esteemed guidance to solve this issue.
    Regards
    Pavitra Dhamija
    Post Doc
    University of Johannesburg
    South Africa
    Reply
    • Ludo Waltman August 24th, 2020 4:06 pm
      When exporting data from Web of Science or Scopus, you need to make sure to include data on the references of publications. To do so, follow the instructions on p. 27 in the VOSviewer manual. I expect this will solve your problem.
      Reply
  • Shelley E Olds August 18th, 2020 9:24 pm
    I want to use the term viewer to analyze my WOS results in a few ways. I've made a nice term map from the results from a rather 'complicated' WOS search. I would like to be able to select terms in the viewed map and see the articles that are associated with that term. Is there a way to do this?
    Then I want to analyze two subsets of WOS datasets - one subset includes the articles that have passed my criteria for title and abstract; the second subset are those that fail. My goal is to identify if there are patterns in the search terms that led to an article passing vs failing.
    It seems like VOSviewer has this association but is hidden away . In the bibliographic maps, the articles can be seen. Your help is much appreciated!
    Reply
    • Ludo Waltman August 22nd, 2020 10:07 pm
      Getting the relations between terms and documents is possible in VOSviewer, but this feature is somewhat hidden. In the final step of the 'Create Map' wizard, a table is presented listing the terms to be included in your map. When you right-click on this table, a context menu will appear that offers an option for exporting the document-term relations to a text file. There is also an option for exporting the terms to a text file. Combined with the original WoS file that was provided as input, this provides all data needed to determine which terms occur in which documents. To further analyze the data, you probably need to use a spreadsheet program or a tool like R or Python.
      Reply
  • Xueting You August 12th, 2020 9:39 am
    When I open a .net file by Pajek, then I use the "VOS Mapping" function of Layout, the application tell me that"VOS Mapping cannot be applied to disconnected networks." What should I do to solve this problem? I'm looking forward for your replay, and thanks very much for your help.
    Reply
    • Ludo Waltman August 16th, 2020 11:45 am
      If you send your Pajek network file to vosviewer@cwts.leidenuniv.nl, I will take a look at the file and try to offer advice.
      Reply
  • Xueting You August 12th, 2020 9:31 am
    I have opened a .net file by Pajek, then I used the "VOS Mapping" function of Layout, but the software told me that "VOS Mapping cannot be applied to disconnected networks." What should I do to solve this problem? I'm looking fordward to your replay, and thanks very much for your kindly help.
    Reply
  • xiangqi August 11th, 2020 10:24 am
    it shows that vosviewer close unexpectedly, help me, please
    Reply
  • sheikh shueb August 8th, 2020 9:18 am
    I am not able to use VosViewer for analyzing large data set consisting of about 50 thousand records downloaded from Web of Science. plz help?
    Reply
  • Mohammad August 7th, 2020 2:46 am
    Hi,
    I need your assistance in clearing an error in a .csv file containing data..
    This is the error I keep receiving when analysing the data:
    'Error while reading Scopus file 'scopus.csv' : null
    Thanks.
    Reply
    • Ludo Waltman August 7th, 2020 10:00 am
      Could you please send your file to vosviewer@cwts.leidenuniv.nl? I will then take a look at your problem.
      Reply
  • Omwoyo Bosire Onyancha July 28th, 2020 12:05 pm
    Hi Ludo,
    Thanks for re-enabling my access to this site after my IP was blocked. Please tell me - how can one determine the distance between two countries in a co-authorship network?
    Reply
    • Omwoyo Bosire Onyancha July 28th, 2020 12:10 pm
      And what does that distance mean?
      Reply
      • Ludo Waltman July 29th, 2020 8:45 am
        Do you mean the distance between two countries in a map of a co-authorship network? In such a map, the distance between two countries approximately reflects the number of co-authored publications of the countries (after normalizing for the total number of co-authored publications of each of the two countries). In general, the closer two countries are located to each other, the larger their number of co-authored publications.
        Reply
        • Omwoyo Bosire Onyancha August 7th, 2020 10:40 am
          Thanks Ludo for the response. Does a co-authorship network provide the distance (in whatever metric) between co-authors (individuals, countries or institutions)? All I get is links, link strength, papers, and citations (with normalized citations). I do not see any metric that may explain the distance.
          Reply
          • Ludo Waltman August 9th, 2020 3:17 pm
            Could you explain what you mean by the distance between co-authors, perhaps by giving an example? At the moment it is not clear to me what you have in mind.
            Reply
            • Omwoyo Bosire Onyancha August 9th, 2020 11:46 pm
              Let me put it this sir: is there a metric to measure a distance between two nodes in a network?
              Reply
              • Ludo Waltman August 10th, 2020 7:11 am
                In VOSviewer, no such metric is provided.
                Reply
                • Omwoyo Bosire Onyancha August 10th, 2020 11:34 am
                  Thanks for the clarification
                  Reply
  • Dan July 26th, 2020 5:16 am
    Hello,
    I'm doing a bibliographic coupling analysis of the document level.
    If I have a document with 20 links and a total link strength 3.
    What does that mean?
    Reply
    • Ludo Waltman July 26th, 2020 8:44 am
      Are you using full counting or fractional counting?
      Reply
      • Dan July 26th, 2020 1:06 pm
        fractional counting
        Reply
        • Ludo Waltman July 27th, 2020 11:17 am
          The total link strength equals the sum of the strengths of the bibliographic coupling links of your focal document with other documents in your bibliographic coupling network. Using full counting, the total link strength will always be greater than or equal to the number of links (since each link has a strength of at least 1), but using fractional counting (see https://doi.org/10.1016/j.joi.2016.10.006 or https://arxiv.org/abs/1607.02452) this doesn't need to be the case.
          Reply
          • Dan July 27th, 2020 12:30 pm
            thank you very much
            Reply
  • Jana Keller July 23rd, 2020 11:24 am
    Hi,
    I would like to ask you if there is a way to save the map generated in a format that can be opened again in Vosviewer.
    Thank you in advance.
    Reply
    • Jana Keller July 23rd, 2020 12:16 pm
      I'm sorry, the solution is so simple:
      I now realized that you have to save both the network and the map file as .txt, then you can open it again in VOSviewer.
      Thanks for this great tool!
      Reply
  • Iloni July 16th, 2020 4:24 am
    Hello
    How do I see the articles that are referenced in a node? For example, in a grouping of citations by countries, how to extract which articles belong to a country and consequently make up the node?
    Reply
    • Ludo Waltman July 18th, 2020 8:46 am
      This information can be obtained in the last step of the 'Create Map' wizard. You need to right-click on the table listing the countries. A context menu will appear in which you can choose to export the relations between countries and documents. Using this option, the relations between countries and documents will be exported to a text file.
      Reply
      • Iloni July 19th, 2020 2:35 am
        Thanks for the answer
        but I still need some help. on the generated map we have the display of several countries. I need to know what research is related to each country. For example, Italy had 40 articles. How to generate a list with 40 articles related to Italy?
        Reply
        • Ludo Waltman July 19th, 2020 1:32 pm
          The only way to get this information is the way I explained in my previous answer. Unfortunately, VOSviewer currently doesn't offer an easier way to get this information.
          Reply
  • Ayushi July 10th, 2020 5:54 pm
    i could not find the VOSviewer.jar file in the downloaded file. can you please help me out
    Reply
    • Ludo Waltman July 13th, 2020 2:19 pm
      The JAR file can be downloaded using the link 'Download VOSviewer 1.6.15 for other systems' on the download page.
      Reply
  • Bosire July 8th, 2020 2:12 pm
    Can somebody please assist me on how to resolve this error that keeps popping up when analysing WoS data?
    "Error while reading Web of Science file 'savedrecs'.text (line 22): Multiple C1 fields".
    It seems like WoS started duplicating the C1 fields for records?
    Reply
    • Ludo Waltman July 22nd, 2020 5:14 pm
      Could you please send your Web of Science file to vosviewer@cwts.leidenuniv.nl? I will then take a look at your file and try to offer advice.
      Reply
      • Camila Silva September 25th, 2020 10:32 pm
        I've had a similar error "Error while reading PubMed file 'pmc_result (2).txt' (line 57): Multiple TI fields". Please, could someone help me?
        Reply
  • María July 4th, 2020 9:18 am
    Hello,
    I want to congratulate you for your efforts creating this tool and helping us with our questions.
    Could you explain the difference on the relationship items have with each other in terms of links and in terms of clusters?
    If the co-word analysis indicates that word A have a link with B it means that both are used together in a text? If so, why could they belong to different clusters? Considering the distance between items is the times they are used together, then how to understand the clustering criterium?
    Maybe it's too easy but I can't get the difference even reading the manual on how can we interpret clusters Vs links or Vs distance between items?
    Thank you so much for your time!
    Greetings
    Reply
    • Ludo Waltman July 18th, 2020 10:33 am
      The proximity of items in a map approximately indicates the relatedness of the items in terms of co-occurrences. Likewise, a cluster indicates a set of items that are relatively strongly connected in terms of co-occurrences. A technical explanation of the clustering criterion can be found in the book chapter available at the top of this page. The essence is that items belonging to the same cluster have a relatively high likelihood of being connected by co-occurrence links, while items belonging to different clusters have a relatively low likelikehood of being connected by co-occurrence links. Note that there will almost always be items that are not assigned to the same cluster even though they are connected by co-occurrence links. This cannot be avoided, unless all items in a map are assigned to the same cluster.
      Reply
      • María August 12th, 2020 12:21 am
        Thank you so much!
        Reply
  • Bosire June 29th, 2020 9:30 pm
    On another issue Prof..
    Have you been able to find out if it is possible for one to increase the memory in macbook laptops? I have tried in vain. The VOSviewer is unable to analyse 69,000 records at one go.
    Reply
  • Bosire June 28th, 2020 10:31 pm
    I need your assistance in clearing an error in a .csv file containing data..
    This is the error I keep receiving when analysing the data:
    'Error while reading Scopus file 'scopus.csv' : IOException reading next record: java.io.IOException: (line 1280) invalid char between encapsulated token and delimiter
    Thanks.
    Reply
    • Ludo Waltman June 29th, 2020 7:49 pm
      This problem is caused by a bug in the Scopus CSV export. Usually the problem can be fixed by leaving out certain types of information from the export. Recently it turned out that the indexed keywords cause problems, so you could for instance try to leave out those. Hopefully the Scopus team will soon fix the bug.
      Reply
      • Bosire June 29th, 2020 9:07 pm
        Thanks Ludo for your assistance. I have realised that the problem was specifically associated with conferences.. Articles seem to be find.
        Reply
  • Omwoyo Bosire Onyancha June 26th, 2020 9:02 pm
    Hi all,
    Please assist me here. Does anyone know why some of 'types of analysis' on VOSViewer, i.e. citation, bibliographic coupling. and co-citation analysis, are inactive (deactivated). I am trying to conduct a citation analysis of journals using Scopus data saved as .csv format.
    Regards
    Reply
    • Ludo Waltman June 26th, 2020 9:50 pm
      When exporting Scopus data to a CSV file, you need to make sure to include reference information. This will solve your problem.
      Reply
      • Bosire June 28th, 2020 7:25 pm
        Thanks Ludo for your reply. I will try again and see what happens.
        Regards
        Bosire
        Reply
      • Bosire June 28th, 2020 10:26 pm
        It worked, Thanks.
        Reply
  • Dan June 21st, 2020 3:26 pm
    Hello,
    I am doing a co-citation analysis at the document level.
    When the Link strength between Article A and Article B is 20.
    Does this mean that Article A and Article B were cited 20 times together by the references of the articles contained in my data set?
    The total strength of Article A is 320. Does this mean that Article A was co-cited in my data set 320 times?
    Reply
    • Ludo Waltman June 21st, 2020 5:08 pm
      Yes, both are correct!
      Reply
  • Frieyadie June 19th, 2020 6:36 pm
    I have a problem. Want to ask, why when Create Map Type analysis Co-Occurance is not active / Disable huh?
    What is the solution?
    Thanks
    Reply
    • Ludo Waltman June 19th, 2020 10:41 pm
      If your input data doesn't include keywords, VOSviewer disables the option for creating a keyword co-occurrence map.
      Reply
      • rosy June 21st, 2020 8:27 am
        I also have the same problem, I already downloaded from PoP with keyword and save the result as RIS, however when a choose create a map with bibliographic data, the co-occurrence fitur was disabled. Could you give me advise about that (VosViewer 1.6.15). Thanks
        Reply
        • Ludo Waltman June 21st, 2020 9:13 am
          Your RIS file apparently doesn't include keywords, so it's then impossible for VOSviewer to create a keyword co-occurrence map. If you want to create such a map, you need to use a data source that does provide keywords (e.g., Web of Science, Scopus, or PubMed).
          Reply
          • rosy June 22nd, 2020 5:38 am
            Thank you Ludo
            Reply
  • giuseppe vito June 19th, 2020 10:05 am
    combining the database from WoS and Scopus:
    see in this blog Giuseppe Vito apr. 9, Ludo Waltman apr. 19, Giuseppe Vito apr. 22.
    Greetings
    Reply
  • Hamdan June 19th, 2020 8:34 am
    Hi,
    If I have an item (publication A) that has: 8 links, the total strength of the links is 15 and citations are 410.
    Does this mean that publication A is cited along with 8 different publications?
    The Link Strength between publication A and publication B is 3.
    Does this mean that publication A and publication B were cited three times in one article or in several articles at the same time?
    Citations 410: Does this mean that publication A was cited 410 times?
    There is a big difference between the number of Citations 410 and the total link strength. What is a possible explanation for this?
    Best regards,
    Hamdan
    Reply
    • Ludo Waltman June 19th, 2020 10:32 pm
      Could you explain what kind of map you have created (e.g., citation, bibliographic coupling, or co-citation)? The number of citations (410) is the total number of citations a publication has received in the database you are using (e.g., Web of Science, Scopus, or Dimensions). So it is not the number of citations received in your data set, but the number of citations received in the entire database. Other statistics, such as the number of links and the total link strength, are based on your data set, not on the entire database.
      Reply
      • Hamdan June 20th, 2020 12:58 am
        Thank you for your quick response.
        I am doing bibliographic coupling.
        and how can we explain the mentioned information in the case of co-citation?
        Reply
  • Koushik Sau June 18th, 2020 12:48 pm
    dear sir if I want to export more than 2000 documents for my field it only provides citation documents then how can I can study which keywords using more in my field. full document export if contain less than 2000 documents
    Reply
    • Ludo Waltman June 19th, 2020 10:14 pm
      I assume you are using Scopus data? You then need to find a way to split your data into batches of no more than 2000 documents each. Perhaps you can do this by creating a separate batch for each publication year.
      Reply
  • ReyaAk June 14th, 2020 6:53 pm
    Is there any possibility that we can combine the database from WoS and Scopus? And analyse it using VOS?
    Reply
    • Ludo Waltman June 15th, 2020 4:11 pm
      Unfortunately this is not possible. There are important differences between the two databases in the file formats they support.
      Reply
  • Manuel June 14th, 2020 8:51 am
    Thank you for this useful tool. I cannot download the Windows version from the Download page. In most cases the download doesn't start ("500 - Internal server error."); if it does, it stops always after downloading 4mb. Is there any alternative, external hosting for this file available?
    Reply
    • Ludo Waltman June 15th, 2020 4:06 pm
      Thanks for reporting this problem. The problem has now been fixed.
      Reply
  • Yeri June 13th, 2020 2:43 pm
    Hello,
    Thank you for your useful tool. I've got one question.
    I used web of science record data for network visualization.
    What I would like to get is the adjacency matrix (diagonal matrix) from this map.
    Could you please kindly let me know how I can get that data?
    Like "journal_network_full.txt" in data folder.
    Best regards,
    Yeri
    Reply
    • Ludo Waltman June 14th, 2020 7:55 am
      The adjacency matrix can be obtained by saving the network underlying your map in a VOSviewer network file. This can be done using the 'Save' button on the 'File' tab. The network file will have a so-called sparse format, which means that only the non-zero entries of the adjacency matrix are stored in the file.
      Reply
  • Ghaliamus June 9th, 2020 6:37 pm
    Hello,
    I thank you so much for your great efforts behind this great software. I have one question please.
    You used PCA in the transformation step (the third step) for the solution (the presented map). What I know about PCA is that the distance between points in the first component (x-axis) dimensions are more important than the distance between points in the second component (y-axis). However, you used more than PCA in your transformation step.
    Now, can I assume that the importance of distances in the VOSviewer maps is the same in both vertical and horizontal perspectives? And therefore, there is no need to care about x-axis and y-axis in describing the produced map?
    Best wishes,
    Ghaliamus
    Reply
    • Ludo Waltman June 9th, 2020 11:04 pm
      The horizontal and vertical axes have no special meaning in a VOSviewer map. What matters are the distances between the items. You may rotate a map and this shouldn't change your interpretation of the map, since the distances between the items remain the same.
      Reply
      • Ghaliamus June 28th, 2020 5:26 pm
        I thank you so much for your response. If I can ask, if axes have no meaning, and if we have item A and item B with the same distance with item C, why we can have item A above item C (in vertical distance) and item B next item C (in horizontal distance), I could understand how VOS find the distance, but how it located such items, I could not get it. I am sorry if I am missing an obvious point here.
        Reply
        • Ludo Waltman June 28th, 2020 7:50 pm
          I am not sure if I understand your question. The details of the VOS layout technique can be found in the following paper: https://doi.org/10.1002/asi.21421 (and also in the book chapter mentioned at the top of this page). As already mentioned, a map can be freely rotated. This doesn't change the interpretation of the map. By default, VOSviewer uses principal component analysis to rotate a map in such a way that the variance in the horizontal dimension is maximized.
          Reply
  • AYNU June 9th, 2020 2:13 am
    Thanks for your continuous support. I have following questions.
    1. Citations, then unit of analysis "country"; then does it show the origins of articles of documents where authors were working?
    2. How to get the "sources of primary data by country" using VOSviewer? or we have to find by reading all articles in the dataset?
    Reply
    • Ludo Waltman June 9th, 2020 11:00 pm
      1. Country means the country mentioned in the affiliations that authors report in their publications.
      2. I am not sure what you mean by 'sources of primary data by country'.
      Reply
      • MD AYNUL HOQUE June 11th, 2020 6:58 am
        Thank you for your kind support. "sources of primary data by country" : For example, an author published an article who is working at Harvard University which is his affiliation but he used data from Malaysia. So the source of data was Malaysia and his affiliation was Harvard. I wanna know how to find source of data using VOSviewer? or is there any other software for this purpose?
        Reply
        • Ludo Waltman June 12th, 2020 11:58 pm
          Thanks for clarifying your question. VOSviewer is unable to determine the source of the data. I am not familiar with any tool that it able to determine this.
          Reply
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