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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  • Alihosein July 16th, 2019 10:35 am
    I am using vosviewer now, I want to add the thesaurus I have made to do co-ocurrence but the error appear. the error is below
    error while reading vosviewer thesarus file (line 26): incorrect number of columns
    I want to know what is the error and how can I fixed it?
    thank you
    Reply
  • GG July 12th, 2019 6:28 pm
    Dear Ludo,
    Thanks for your comments and work.
    I performed a co-citation analysis (from Web of Science). I get the references (papers) with the cluster number. I export the result (save VOSViewer map file), visible with excel. Each reference has an ID.
    My question is: how can I generate a file that indicates ID, authors, journals... and abstract? (my goal is to perform a lexical analysis of abstracts while keeping the cluster number).
    Thanks again !
    Reply
    • Ludo Waltman July 13th, 2019 7:07 am
      I am afraid that abstracts are not available for the references in data downloaded from Web of Science. They are available only for the documents in data downloaded from Web of Science, not for the references in these documents. Perhaps you could do a bibliographic coupling analysis instead of a co-citation analysis, since a bibliographic coupling analysis is based on the documents in your data, not on the references in these documents.
      Reply
  • A.A. July 11th, 2019 10:37 am
    Dear all,
    How can I expand my map as in adding other items to my existing map?
    Thank you.
    Reply
    • Ludo Waltman July 12th, 2019 7:22 am
      VOSviewer does not have any functionality for expanding maps. However, you can do this manually by saving your map in a VOSviewer map file and by editing this file in a spreadsheet program such as MS Excel. In Excel, you can then manually add new items to your map.
      Reply
  • Lurdes July 7th, 2019 3:03 am
    Hello Ludo,
    It's possible, to know the articles with highest co-citation frequencies?
    Thank you,
    Lurdes
    Reply
    • Ludo Waltman July 7th, 2019 4:01 pm
      When you have created a co-citation map of documents, the total link strength of a document indicates the total number of co-citations the document has with other documents included in your map.
      Reply
    • Lurdes July 8th, 2019 12:41 am
      Thank you.
      Another subject, the authors' country calculation on VOSviewer (Citation/Countries) is different from that calculated by the Web of Science, for some countries.
      Reply
  • Cesar França June 28th, 2019 3:17 am
    Please,
    How can I use the text mining functionality of VOSviewer?
    Thank you!
    Cesar Franca
    Reply
  • Trang Pham June 26th, 2019 5:18 am
    Dear all,
    I am very interested in your VOS viewer.
    One issue I am concerned is that does your VOS viewer can run database fromWeb of Science- Thomson (all database) or only Web of Science (Core Collection)?
    Hope to hear from you soon.
    Reply
    • Ludo Waltman June 27th, 2019 10:29 am
      Both are supported, but data from the Core Collection offers additional possibilities. Using Core Collection data, it is possible to create citation-based maps. This is not possible using data from all databases.
      Reply
  • Jessica Bell June 19th, 2019 3:35 pm
    When creating a keyword thesaurus, I'm getting an error that there are the same terms in the label column as in the replace by column and there are not. I didn't receive this error yesterday, but am today. I have no idea what I'm doing incorrently!
    Reply
    • Ludo Waltman June 20th, 2019 11:39 pm
      Please send your file to vosviewer@cwts.leidenuniv.nl and I will take a look at your problem.
      Reply
  • Julea Shaw June 11th, 2019 8:40 pm
    When creating a keyword co-occurrence map, you are able to choose the minimum number of occurrences of a keyword in order to include it in the map. How do you know what the threshold should be to include a term?
    Reply
    • Ludo Waltman June 12th, 2019 7:41 am
      My recommendation is to try out different thresholds to explore the effects on the selection of keywords and on the map that is obtained. In general, it is recommended to create multiple maps based on different parameter choices in order to explore the sensitivity of the results to the parameter choices. In a map, you can see for each keyword how often it occurs. In this way, you know for each keyword whether it will be included or excluded for a specific choice of the minimum number of occurrences threshold.
      Reply
  • Andy Yeung June 6th, 2019 10:39 am
    Fractional counting of authorship: Does fractional counting affect the strength of "link" only, or can it adjust for the actual count when the map.txt is viewed in Excel? I want to check out the adjusted count, which is impossible from Web of Science's Analyze function. Thank you.
    Reply
    • Ludo Waltman June 8th, 2019 10:33 am
      Could you please clarify your question. What do you mean by 'actual count' and 'adjusted count'?
      Reply
      • Andy Yeung June 8th, 2019 3:52 pm
        Actual count is the count obtained by full counting. But I want to see a count that is adjusted by co-authorship. For example, if a paper is authored by both Chinese and USA authors. By full counting, China = 1 and USA = 1. By fractional counting, China = 0.5 and USA = 0.5. Can the values from the latter be found in the map.txt? I know that the link strength changes if I choose fractional counting instead of full counting, but link strength is not what I want.
        Reply
        • Ludo Waltman June 8th, 2019 5:31 pm
          VOSviewer does not provide this type of fractional counting statistics. Fractional counting is available only for the calculation of the link strengths, not for the calculation of the weights of the items.
          Reply
          • Andy Yeung June 9th, 2019 12:39 am
            Thank you for your clarifications!
            Reply
  • Andy Yeung June 6th, 2019 9:55 am
    Hi - Is it possible to search only for publications in WoS that have an PMID? I would like to present visualizations together with data of MeSH descriptors. Hence, I am not interested in publications not indexed in PubMed.
    Ultimately, I want to define a body of literature by MeSH descriptors, get their bibliometric data from WoS (or Scopus), and visualize by VOSviewer. Is that possible?
    Reply
  • Anne Zehoul June 5th, 2019 7:45 pm
    Hello
    I am a first time user of VosViewer, and got stuck in the first step : when I try to select the SCopus csv file it appears a message :
    Error while reading Scopus file 'xx': IOException reading next record: java.io. IOException : (line2) invalid char between encapsulated token and delimiter.
    Do you know how to fix it ?
    tks a lot !
    Reply
    • Ludo Waltman June 5th, 2019 8:23 pm
      This is a bug in the Scopus CSV export. We are in contact about this with the Scopus team at Elsevier. They are working on fixing the bug. As a temporary workaround, you could try to export only selected fields rather than all available fields. In particular, excluding abstracts from the CSV export might help.
      Reply
      • Anne Zehoul June 5th, 2019 11:52 pm
        Thank you Ludo !
        Reply
  • PJH June 4th, 2019 9:42 pm
    Is dimensions data downloaded and analyzed in VOSviewer or only in Dimensions.
    Philip
    Reply
    • Ludo Waltman June 4th, 2019 9:47 pm
      You need to download data in the Dimensions web interface. The data can then be provided as input to VOSviewer. We are exploring possibilities for a more convenient connection between Dimensions and VOSviewer.
      Reply
  • Alex June 4th, 2019 6:06 pm
    Hi - Is it possible to automate the uploading of multiple .csv files via the 'create files based on text data' option and the 'read data from bibliographic database files' specifically? And then confirming all the following options? I've consulted section 5.1 and can't see anything, but as I'm not really familiar with command line procedures I may be missing something. So any pointers would be much appreciated.
    Thanks,
    Alex.
    Reply
    • Ludo Waltman June 4th, 2019 9:50 pm
      This is indeed not possible at the moment. Perhaps we can add this feature in the future. However, I am afraid I cannot make any promises. There is a long list of features that we would like to add to the software, but unfortunately our resources are limited. Thanks for making this suggestion!
      Reply
      • Alex June 5th, 2019 9:11 am
        OK, thank you for confirming!
        Best of luck and kind regards,
        Alex.
        Reply
  • PJH June 4th, 2019 2:36 am
    We wrote a bibliometric paper using VOSviewer where the editor asked if we could confirm the results with a second database (we used Scopus). Given that in the field(s) being reviewed (management-education) Scopus coverage is much broader than WOS, I don't really see the point of this. I think it is a request from someone who doesn't really understand the relevant factors.
    In any case, if we can't convince the editor otherwise, am I correct that there is no way to combine databases from Scopus and WOS together into a single analysis? The best we could do would be to run a second search in WOS and then compare the results?
    Thanks.
    Philip
    Reply
    • Ludo Waltman June 4th, 2019 3:25 am
      Yes, you are right, there is no straightforward way in which data from different data sources can be combined.
      By the way, instead of, or in addition to, Web of Science, you could also consider the use of Dimensions.
      Reply
  • Treshani June 3rd, 2019 11:47 am
    Hi Ludo,
    Could you please tell me if there is any possible way to show two terms together when mapping based on text data (from title and abstract).
    For instance, I want 'virtual reality' as a single label on the map, but my map shows 'reality' separately.
    Thanks
    Treshani
    Reply
    • Ludo Waltman June 3rd, 2019 5:13 pm
      If you don't want 'reality' to be included in your map, you can use a thesaurus file to remove it. You can also use a thesaurus file to merge 'reality' and 'virtual reality', if this is what you want.
      When identifying terms in titles and abstracts, VOSviewer identifies the longest possible terms. Hence, if a sentence includes the phrase 'virtual reality', this is counted as an occurrence of the term 'virtual reality', not of the term 'reality'. However, if for whatever reason the term 'virtual reality' is not included in your map, occurrences of 'virtual reality' will be counted as occurrences of 'reality'.
      Reply
  • Pedro Silva May 28th, 2019 7:12 pm
    I have been playing around with VOSviewer and CItNet, trying to distill some insights from a search query which yielded >4900 hits in Web of Science. Among other things, I had VOSviewer generate a keyword map. Obviously, with such a large number of records I got a large interconnected map but only 5 major clusters. That is fine, but I wonder if there any simple way to modify the program so that one can retrieve (from VOSViewer) the identities of the papers which contribute to each cluster (or to a selected number of terms from a cluster. That would be tremendously helpful when preparing,e.g, a systematic review of the literature: using vosviewer to find broad subfiels, then zooming into a specific region of interest to obtain a manageable group of papers.
    Reply
    • Ludo Waltman May 29th, 2019 3:09 am
      There currently is no easy way to accomplish this. However, when you create a map, in the final step of the 'Create Map' wizard, a table is shown listing the keywords to be included in the map. By right-clicking on this table, it is possible to export the document-keyword relations. By combining the document-keyword relations with the keyword-cluster relations (which can be obtained by saving your map in a VOSviewer map file), it is possible to find out which documents contribute to which clusters. In principle, this offers a solution to your problem, but it is not a very easy one.
      Reply
      • Pedro Silva May 29th, 2019 8:04 pm
        I have followed your instructions and see how it can be done. Thanks! The "only" glitch is that papers are identified by number in the document-keyword file, and in a long list of documents it could be difficult to avoid mistakes when selecting them by hand afterwards.
        Do you think it would be possible to include (in a future update) a simpler way to do that?
        Reply
        • Ludo Waltman May 29th, 2019 10:41 pm
          I cannot promise anything, but I hope we will be able to simplify this in the future.
          Reply
  • PJH May 23rd, 2019 4:41 am
    Hi
    I'm looking at the feasibility of a review project and identified around 40,000 relevant documents in Scopus. Scopus would only allow export of 'citation information' for 20,000 documents at a time. So I tried that and got access to a csv file with 20K documents in it with basic info plus citations.
    However, when I ran it to see what kinds of analyses I'd be able to do in VOSviewer, the only analysis available was co-author of authors. Everything else was grayed out.
    What am I missing or doing wrong here? And, can you suggest a way to get this info from Scopus in a reasonably efficient way. Or would WOS be any better?
    Thanks.
    Philip
    Reply
    • PJH May 23rd, 2019 7:08 am
      With some more work I figured one way to deal with this in Scopus (not sure if it's the best).
      1. Identify documents (40,000 [plus)
      2. Save to independent lists (
      Reply
      • Ludo Waltman May 23rd, 2019 9:28 am
        Unfortunately, the functionality in Scopus for exporting up to 20,000 records is of limited use, since a lot of data will not be included in the resulting file. To get all relevant data, you need to use the regular export functionality of Scopus, which supports a maximum of 2,000 records. You may need to find ways to split up your search results in batches of at most 2,000 records (e.g., by making a breakdown by publication year).
        Reply
  • giuseppe vito May 22nd, 2019 7:21 pm
    Dear Ludo,
    I created an Author Keywords map with bibliographic data from Web of Science (limit: 2 occurrences).
    Many Keywords obtained with Vosviewer are not present in those mentioned by the Author in the full text of the paper.
    What can the explanation be?
    The format of the scores in the Vosviewer map files is not numerical, whether I open them with Excel (2019) or OpenOffice (2019).
    Can you help me?
    Thanks in advance
    Reply
    • Ludo Waltman May 22nd, 2019 8:17 pm
      You probably also included KeyWords Plus. These are keywords assigned algorithmically to publications by Web of Science. These keywords need not occur in the publications themselves.
      Reply
  • Atefeh Zolfagharnasab May 20th, 2019 9:02 am
    Hi dear Ludo
    You said in this article "Text mining and visualization using VOSviewer", VOSViewer can use for text mining.
    There was a function In data mining that called "associated rules". Can we call the co-occurrence a branch of associated rules?
    Reply
    • Ludo Waltman May 20th, 2019 9:05 am
      I don't think co-occurrences can be seen as a branch of association rules. Instead, I think co-occurrences provide the basis for deriving association rules.
      Reply
      • Atefeh Zolfagharnasab May 20th, 2019 9:08 am
        Thank you so much
        Reply
  • Joăo Pildervasser May 15th, 2019 3:37 am
    Hi Ludo,
    When creating a text map using data from WoS (journal: "New Phytologist", year: 2016-2019) and selecting the overlay visualization using "avg. pub. year" the year range automatically generated goes from 2017.2 to 2017.5. If I manually set it to 2016-2019 the map becomes monochromatic as if all publications are from mid-2017. What's the reason for that and is there a way to solve it? Thanks
    Reply
    • Ludo Waltman May 17th, 2019 9:18 am
      The color of a term reflects the average publication year of the publications in which the term occurs. For almost all terms, this average publication year will be somewhere in the middle of your period of analysis. This is why in your case the colors are concentrated between 2017.2 and 2017.5. You can click on the color bar to manually change the year range to 2016 and 2019. You will see that the terms then almost all have the same color, making the color coding of little use.
      Reply
  • Dennis Lundberg May 13th, 2019 4:03 pm
    We are moving away from Oracle's Java because of the changed license terms. Instead we are deploying AdoptOpenJDK, which is a distribution of OpenJDK.
    We are unable to start the downloadable executable of VOSviewer on neither Windows 10 nor MacOS X. All we get is an error message saying "Unable to run the Java runtime environment.
    What can we do to run VOSviewer on OpenJDK? Is there a configuration option that we can use to tell VOSviewer which version of Java to use?
    Reply
    • Ludo Waltman May 13th, 2019 9:22 pm
      Perhaps you could try to run the VOSviewer JAR file, which can be downloaded from http://www.vosviewer.com/download as 'VOSviewer 1.6.11 for other systems'. Please let me know if this doesn't solve your problem.
      Reply
      • Dennis Lundberg May 14th, 2019 4:21 pm
        Thank you!
        That worked for me.
        Reply
  • Atefeh Zolfagharnasab May 12th, 2019 10:08 am
    Hi
    I had phrases that their characters were more than 20 and when map was created these phrases were not shown completely. How can I see them completely in the map?
    Reply
    • Ludo Waltman May 12th, 2019 10:26 pm
      I'm not sure whether I understand your question correctly, but perhaps your problem can be solved by increasing the value in the 'Max. length' text box in the options panel in the right part of the VOSviewer window.
      Reply
  • Pedro Silva May 8th, 2019 5:40 pm
    The manual states that when extrating terms from a bibliography VOSviewer by default only considers terms which appear in more than 10 documents. Is there a possibility for the user to change this? I have searched the maual and could not find anything on that
    Reply
    • Pedro Silva May 8th, 2019 6:00 pm
      I just discovered that those opions appear when I upload the bibliography bibliographic database format (like PubMed) but it is not available when using reference manager formats (like *ris). What is the technical reason for this?
      Reply
      • Ludo Waltman May 9th, 2019 12:24 pm
        The option is also available for RIS files. You've probably overlooked it. PubMed and RIS files are handled in the same way by VOSviewer.
        Reply
        • Pedro Silva May 9th, 2019 12:50 pm
          I see now that I clicked finish too soon and therefore overlloked that menu. Thanks for pointing out my error.
          I am also finding trouble with thesuaurus files: I have a pubmed_results file with 4500 abstracts and around 10200 authors. around 800 of the author names are different forms of the names of the same people and therefore I made a thesaurus file . When loading it, I got several error warnings claiming that I have the same name in the two columns, though those names look to me different (e.g. utesch , tillman and utesch , tillmann). I guess there are limitations when the replce by is a substring of the label column (or the other way around, I am not sure). ANyway, I got around all of those errors but when VOSviewers shows me the terms, it still claims it has found 10200 individual authors and when plotting I still find nodes corresponding to the individual names, just as if no thesaurus file had been read. What should I do? I am sure I am making a ver stupid newbie mistake, maybe in the formatting of the thesaurus file or whatever..... :-(
          Reply
  • Treshani May 8th, 2019 1:41 pm
    Hi Ludo,
    Is there a possible way to merge Scopus (csv) and Web of science (txt) files together to build a bibliographic network.
    Reply
    • Ludo Waltman May 8th, 2019 3:39 pm
      I'm afraid this is rather difficult. To the best of my knowledge, there is no straightforward way in which this can be done.
      Reply
  • Ying May 7th, 2019 6:56 pm
    Dear Dr. Ludo,
    I am interested in investigating the theme differences in research journals and practitioner-oriented journals/magazines in my discipline. However, the articles in non-refereed journals have no abstract.
    So my question is that can VOSviewer be used to analyze the keywords in non-referred journals/magazines?
    Reply
    • Ludo Waltman May 7th, 2019 9:15 pm
      If you have access to the data required for carrying out such an analysis, I believe this should be possible.
      Reply
      • Ying May 8th, 2019 1:55 am
        Dr. Ludo,
        Thank you so much for your quick response!
        I tested the keyword analysis with the magazine data (from the title and abstract field) and the results did show up like a normal term map.
        One question adding to that is which part of the content was used as the source for extracting the terms when there is no abstract in the data?
        Reply
      • Ying May 8th, 2019 4:09 am
        Dr. Ludo,
        Sorry for making confusion in the last question.
        I think I really want to ask is that which type of creating the map can analyze the whole text instead of the title and abstract (i.e. create a map on bibliographic data for keyword co-occurrence analysis, or create a map based on text data for term analysis)?
        Thank you in advance for reading the message.
        Reply
        • Ludo Waltman May 8th, 2019 7:11 am
          If you want to use full text data, not just titles and abstracts, you need to provide the full text data as input to VOSviewer in a so-called corpus file. In the 'Create Map' wizard, you first need to choose the option 'Create a map based on text data', followed by the option 'Read data from VOSviewer files'. Information about corpus files can be found in the VOSviewer manual.
          Reply
  • Oguzhan Alasehir May 4th, 2019 3:39 pm
    Dear Dr. Ludo,
    I need to convert thousands of txt files (containing abstracts of articles) to pure terms. Vosviewer can achieve it perfectly by applying "Create a map based on text data". However, the problem is about how to do it for thousands of times. Could you please provide a good solution for this requirement?
    Best regards,
    Reply
    • Ludo Waltman May 4th, 2019 4:11 pm
      Using the command-line parameters supported by VOSviewer (see Section 5.1 in the VOSviewer manual), it should be possible to automate this task. You will need to program a simple script for this.
      Reply
      • Oguzhan Alasehir May 4th, 2019 4:58 pm
        Thx for quick reply.
        I just tried this solution. It seems working partially. The missing part is how to export the list of terms and their occurences. The interface has an option "Export Selected Terms" when I right click. However, I couldn't find any parameter in command line.
        Btw, as an alternative solution, may I find open source codes for preprocessing of my text files where I can get the same results with VOSviewer.
        Best regards,
        Reply
        • Ludo Waltman May 4th, 2019 5:16 pm
          Yes, that part is indeed missing. I'm afraid I don't have an immediate solution for this. VOSviewer will be made open source later this year.
          Reply
  • Giuseppe Vito May 3rd, 2019 8:51 pm
    Dear Ludo, MY APOLOGIES
    Author Keywords map (network file *.csv or *.xlsx):
    We have: weight (Links), weight (Total link strength), weight (Occurrences), score (Avg. pub. Year), score (Avg. citations).
    How do you calculate score (Avg. norm. citations)?
    Many thanks, sorry for the mistakes in the two previous mail
    Reply
    • Ludo Waltman May 3rd, 2019 9:50 pm
      See p. 37 in the VOSviewer manual.
      Reply
  • Giuseppe Vito May 3rd, 2019 8:46 pm
    Dear Ludo,
    sorry, I clarify:
    Author Keywords map (network file *.csv or *.xlsx):
    We have: weight (Links), weight (Total link strength), weight (Occurrences), score (Avg. pub. Year), score (Avg. citations)
    How do you calculate score ?
    Many thanks
    Reply
  • Giuseppe Vito VITO May 3rd, 2019 8:42 pm
    Dear Ludo,
    Author Keywords map (network file *.csv or *.xlsx):
    We have weight, weight, weight, score, score
    How to calculate score ?
    Many thanks
    Reply
  • Joe Shmoe May 3rd, 2019 2:23 am
    How is the average publication year in the overlay map calculated?
    Reply
    • Ludo Waltman May 3rd, 2019 7:13 am
      This is explained on p. 37 in the VOSviewer manual. Please let me know if this explanation is insufficient.
      Reply
  • John Collis April 30th, 2019 3:08 pm
    Hello,
    I have a csv file delimited by commas. When I try to import it into VOSviewer I get an error message "error while reading VOS map file (line 1) : Total is not a valid column header@. I am running on Windows 10
    Reply
    • Ludo Waltman April 30th, 2019 4:30 pm
      A map file should follow the format described in the VOSviewer manual. Indeed 'total' is not a valid column header. Please see the VOSviewer manual for more details about the format of map files.
      Reply
  • Atefeh Zolfagharnasab April 30th, 2019 11:08 am
    Hello
    I have 2 questions:
    1. When a map is created based on text data, in my density visualization, I see some words apart from other words. For example, "herbal medicine" is close to "effect" and away from "alternative medicine." Does this distance have a special meaning?
    2. in first step, I created a map based on text data for "spiritual health" subject area, and in clusters I selected "traditional medicine" because there were a strong links between "alternative medicine" and "traditional medicine". then I searched for"traditional medicine" in databases and created a map for related terms about "traditional medicine" again but when map was created, "alternative medicine" had weak link with "traditional medicine". Do theses links have a special meaning?
    Reply
    • Ludo Waltman April 30th, 2019 1:12 pm
      Regarding your first question, the distance between two terms approximately indicates their relatedness, where the relatedness of terms is measured by co-occurrences in publications. In general, the smaller the distance between two terms, the more strongly the terms are related.
      I don't fully understand your second question, so I'm afraid I cannot answer that one.
      Reply
  • Jordan Wrigley April 29th, 2019 7:32 pm
    Hello!
    I'm trying to create a citation, bibliographic coupling, or co-citation map based on data from Scopus and/or Web of Science. But, the options for those mapping types are grayed-out and can not be selected no matter which file type I use. Any idea what I need to do? Is there maybe a column I should rename?
    Cheers!
    Jordan
    Reply
    • Ludo Waltman April 29th, 2019 8:10 pm
      Make sure to download all data elements provided by Scopus and Web of Science. This is essential to create citation-based maps. See p. 27 in the VOSviewer manual for more detailed instructions.
      Reply
  • Lin Jo April 28th, 2019 4:38 pm
    Hi, after importing the csv file to vosviewer for making a bibliographical coupling I noticed that there is not the right number of documents. I have 6 csv's do upload and in the each of them there are one or two documents absent after importing. When I open the csv with exell there are all documents included. Can you please tell me how to solve it so that I have all document included?
    Reply
    • Ludo Waltman April 28th, 2019 10:50 pm
      Could you give a bit more details? For instance, how many documents do you have in each of your CSV files? How do you determine the absence of specific documents in VOSviewer? If you could provide some further information, I'll hopefully be able to provide some helpful advice.
      Reply
      • Lin Jo April 29th, 2019 12:21 pm
        It is a csv from scopus export , which has 871 documents, after import this one file vosviewer shows a window „of the 870 documents, 870 meet threshold.“ so that means there is 1 document lost. But why? And this happens with other csv‘s too.
        Reply
        • Ludo Waltman April 29th, 2019 3:27 pm
          Thanks for the additional explanation. Could you send your CSV file to vosviewer@cwts.leidenuniv.nl? We'll then investigate your problem in more detail.
          Reply
  • Lurdes Simao April 27th, 2019 8:38 pm
    Dear Dr. Ludo,
    I exported the Mendeley articles from format RIS.
    But when I try to "Create a map", I don´t have all options. For example, I have only two "Type of analysis": "Co-authorship" and "Co-occurrence", therefore, are missing "Bibliographic coupling" and "Co-citation".
    Concerning "Unit of analysis" I have only "Authors" and "Keywords".
    I sent a e-mail to vosviewer@cwts.leidenuniv.nl with RIS file and a VOSviewer image.
    Have you any suggestion, please?
    Thank you.
    Reply
    • Lurdes Simao April 27th, 2019 8:47 pm
      now I saw the answer:)
      "data in a RIS file cannot be used for identifying citation, bibliographic coupling, and co-citation links between items."
      Reply
  • Syed Asif Raza April 20th, 2019 6:48 pm
    Dear Dr. Ludo,
    Thank you for comments.
    Regarding the co-citation matrix. Is there any video based (or document) tutorial for co-citation matrix creation.
    I noticed that while, I created co-citation matrix with Bibexcel, I got duplication references (paper) and many of these in the co-citation matrix. Is there any way to avoid this problem while using the VosViewer.
    Kind Regards,
    Syed A. Raza, PhD
    Reply
    • Ludo Waltman April 21st, 2019 10:17 am
      In the case of a co-citation analysis, there may indeed be problems with multiple references that point to the same cited work but that differ in minor ways (e.g., in the way the source title is written). Using Web of Science, these problems tend to be relatively minor, but in the case of Scopus, these problems can be large. VOSviewer doesn't solve these problems, but it does offer the possibility of providing a thesaurus file as input. A thesaurus file can be used to solve the problem by manually specifying that certain references should be merged.
      Reply
  • Mayo April 18th, 2019 12:53 pm
    Please how do i resolve this error.
    "Error while reading VOSviewer network file(line 2): Incorrect number of columns"
    Thank you.
    Reply
    • Ludo Waltman April 20th, 2019 6:04 am
      Apparently the number of columns in line 2 in your network file is not correct, or at least it is not consistent with the number of columns in line 1 in your network file. Each line in a network file should have the same number of columns, either 2 or 3.
      Reply
      • Mayo April 20th, 2019 7:16 am
        while i understand your explanation, this is a .csv downloaded directly from web of science. how do i troubleshoot it without tampering with the other data in the sheet.
        however, i have used the .txt and that worked perfectly fine for me.
        thank you.
        Reply
        • Ludo Waltman April 20th, 2019 1:26 pm
          To my knowledge, CSV files cannot be downloaded from Web of Science, only text files. More importantly, the error message in your original message is about a network file, not about a Web of Science file. It therefore seems that you have chosen an incorrect option in the 'Create Map' wizard.
          Reply
  • Howard Ramirez-Malule April 11th, 2019 8:26 pm
    Dear all,
    I have troubles uploading the CSV files exported from scopus. Do you have any suggestion for solving the problem?.
    Error:
    IOException reading next record: java.io.IOException: (line 593) invalid char between encapsulated token and delimiter.
    Thank you very much in advance.
    Best regards,
    Reply
  • Howard Ramirez-Malule April 11th, 2019 8:24 pm
    Dear all,
    I have troubles uploading the CSV files exported from scopus. Do you have any suggestion for solving the problem.
    IOException reading next record: java.io.IOException: (line 593) invalid char between encapsulated token and delimiter.
    Thank you very much in advance.
    Best regards,
    Howard
    Reply
    • Ludo Waltman April 13th, 2019 7:15 am
      Could you send your Scopus CSV file to vosviewer@cwts.leidenuniv.nl? We will then investigate your problem. Thanks!
      Reply
  • Raysa Rocha April 11th, 2019 6:08 pm
    Good afternoon,
    I would like to know what the definition criteria are for choosing the 10 repetitions of the words in the full screen of a co-occurrence network map.
    I have 67 articles, the result with the default was totally different from when we decreased the amount of articles to 6.
    I would like an orientation on the length or lack of a co-occurrence amount.
    Sincerely
    Reply
    • Ludo Waltman April 13th, 2019 2:54 am
      Could you clarify your question? I don't fully understand your message.
      Reply
  • Bárbara Cartagena da Silva Matos April 11th, 2019 3:09 pm
    Hi!
    Is it possible to import data from Excel spreedsheet to VosViewer? If yes, how?
    Thank you,
    Barbara
    Reply
    • Ludo Waltman April 13th, 2019 2:48 am
      I am afraid this is not possible.
      Reply
  • PJH April 4th, 2019 1:55 am
    Could you please provide a concise definition that could be used in an article to clarify the meaning of 'total link strength' as used in citation and co-citation analysis in VOSviewer. If the operational definition differs for the two types of citation analysis, please clarify that as well.
    Thanks.
    Reply
    • Ludo Waltman April 20th, 2019 3:49 pm
      Some definitions are provided in Chapter 2 in the VOSviewer manual. I'm happy to provide specific definitions for citation and co-citation analysis, but I then need to know your unit of analysis (e.g., documents, authors, or sources). Could you let me know your unit of analysis?
      Reply
  • Alisa Mujkic March 31st, 2019 9:51 pm
    Dear dr. Ludo,
    please help us. :)
    We downloaded the collected papers available in Scopus for the journal we are interested in. However, there are additional 400 papers that are not available in Scopus, but in Science Direct, since the journal was not included in Scopus all the time.
    Is there any option to add those 400 papers in VOSviewer automatically or we have to go through this process manually? And please let us know which options we have to choose to do that in context of application itself?
    Best regards and thank you in advance,
    Alisa
    Reply
    • Ludo Waltman March 31st, 2019 11:02 pm
      I'm afraid there is no easy way to add these 400 publications. I don't think it can be done automatically. I'm not sure how you want to do it manually. Manually adding publications to a CSV file exported from Scopus often causes problems.
      Perhaps there's an other data source (e.g., Web of Science or Dimensions) that indexes the 400 publications that you're interested in?
      Reply
      • Alisa April 1st, 2019 9:04 am
        Dear dr. Ludo,
        thank you for your swift response and suggestion. However, other sources such as WoS or D do not have these papers - seems like the databases are “younger” then Scopus : S
        Finally, it turns out that the best possible solution for us is to change a topic.. :)
        Best,
        Alisa
        Reply
  • Sana March 30th, 2019 8:05 pm
    How to increase the memory? I cannot find JAR file as its not in download folder?
    Reply
    • Ludo Waltman March 31st, 2019 9:46 am
      To obtain the JAR file, use the link 'Download VOSviewer 1.6.10 for other systems' on the 'Download' page on the VOSviewer website.
      Reply
  • PJH March 29th, 2019 12:47 am
    A colleague asked me a question and I'd like to confirm if my response was accurate and complete. She asked"why do some authors shift between 2 clusters depending on the threshold I set?"
    I said, "Any author's co-cited publications will contain a distribution of documents, each of which has a different number of co-citations. Moreover, an author's publications may reflect different topical emphases. When you change the threshold, a different set of publications will be analyzed and the displayed clusters may shift. In these cases, however its likely that these shifts will be to an adjacent cluster. Since this isn't a case of 'right or wrong' select the cluster display that makes more sense in terms of the full set of relevant interpretation criteria "
    Is that explanation correct?
    Reply
    • Ludo Waltman March 29th, 2019 6:45 am
      This explanation seems correct to me. In addition, when your colleague follows your advice, in her report I believe she should briefly explain the approach that she has taken, so she should explain that multiple thresholds have been considered and that the one that seems to give the most easily interpretable results has been chosen.
      Reply
  • JK March 28th, 2019 2:01 pm
    Hi Ludo,
    I have a dillema in relation to author co-citation analysis in those cases when a paper is written by multiple authors.
    In VOSViewer manual I have found a following statement: „At the level of cited authors, author names extracted from the raw reference strings are used as the unit of analysis. When working with Web of Science or Crossref JSON files, only first authors are taken into account.“
    Does this mean that if I extract the data from SCOPUS in .csv format, names of all authors working on a paper will be taken into account in author co-citation analysis?
    Thank you.
    Reply
    • Ludo Waltman March 28th, 2019 11:19 pm
      Yes, correct, in the case of a Scopus CSV file, all authors of a publication will be included in an author co-citation analysis.
      Reply
  • Riffat March 25th, 2019 6:59 am
    i am working on VOS viewer by using web of science data while i run bibliometric analysis i use to run commend of open to vos map but it give me error that 100 line header is invalid how can i remove this?
    Reply
    • Ludo Waltman March 25th, 2019 7:50 am
      Could you send your Web of Science file to vosviewer@cwts.leidenuniv.nl? I'll then take a look at your problem.
      Reply
  • Syed A. Raza March 19th, 2019 10:41 am
    Dear Support staff,
    I like to ask about the co-citation analysis in VOSviewer. How we can export the citations (references) that are classified into clusters by software into exportable files (or we can copy them) such as txt, excel, file formats etc. for our analysis?
    Looking forward to hearing from you soon.
    kind Regards,
    Syd A. Raza, PhD
    razasyedasif1@gmail.com
    Reply
    • Ludo Waltman March 19th, 2019 5:07 pm
      You can use the 'Save' button on the 'File' tab for this purpose. Save your map in a VOSviewer map file. This is a tab-delimited plain text file that can for instance be opened in a spreadsheet program such as MS Excel. The information that you are interested in can be found in the map file.
      Reply
      • Syed Asif raza March 23rd, 2019 7:14 am
        Dear Dr. Ludo,
        Many thanks for your assistance.
        Can you please also guide us, how to get the co-citation matrix from VOSviewer?
        Kind Regards,
        Syed
        Reply
        • Ludo Waltman March 23rd, 2019 10:56 pm
          In addition to a VOSviewer map file, you can also save a VOSviewer network file. The latter file includes the co-citation matrix.
          Reply
  • Katie Hoemann March 15th, 2019 11:06 pm
    I am wondering if someone can help me understand how number of links and number of citations are determined for a document-level citation network. We're working with a list of 476 documents, one of which is cited by roughly 60-70 of the others (as determined by a string search through the input WoS file for the author, year, journal, and starting page). However, this document has only 6 links in the network. The same document has 491 citations, which exceeds the number of documents in the input data, but is far fewer than the number of citations given on WoS.
    Reply
    • Ludo Waltman March 16th, 2019 7:28 am
      If you send your input file to vosviewer@cwts.leidenuniv.nl, I will take a look at this issue.
      Reply
  • Pedro March 12th, 2019 1:52 pm
    Dear Ludo,
    In a bibliometric network of countries, the diameter of circles are proportional to the number of publications. Their color represents which community that country has a major interaction with? How this interaction can be expressed/calculated? Based on the number of times they cite each other? Articles together? On other hand, the thickness of the lines is equal to the authors network (i.e., the thickness are proportional of the number of times they cite each other)?
    Thanks a lot for your answers!!!
    Reply
    • Ludo Waltman March 12th, 2019 11:05 pm
      The answer to your question depends on the type of map your have created. Countries are clustered based on their relatedness. In the case of a co-authorship map, relatedness is determined by co-authored publications. In the case of a citation-based map, relatedness is determined by citation links.
      Reply
      • Pedro March 13th, 2019 2:11 pm
        Dear Ludo,
        I have created a citation-based map. Then, the relatedness is determined by citation links (number of times they cite each other). Thanks a lot!!
        Reply
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