Getting Started

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

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VOSviewer manual

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

Open VOSviewer manual

 

VOSviewer book chapter

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

Open VOSviewer book chapter

VOSviewer paper

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

Open VOSviewer paper

AIDA bookletAIDA booklet

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

Open AIDA booklet

Comments

Mandatory fields
  • Fabiola Andrade February 13th, 2019 2:39 am
    Dear Ludo and Team,
    I tried to build an. xlsx file with the same basic items as the files generated by the WoS platform (publication type, authors, references, keywords, titles, etc.), so that you can later apply the. txt file to VOS. However, when I insert the latter, the software displays the following message (which prevents me from continuing the mapping): "Error while reading the Web of Science file (file name) (line 25): Incorrect number of columns". Is there anything that you or I can do to generate the maps?
    Reply
    • Ludo Waltman February 13th, 2019 7:54 am
      This error message means that your file doesn't properly follow the WoS file format. It is not so easy to create your own files in the WoS file format. This often causes problems for VOSviewer users. If you send your file to vosviewer@cwts.leidenuniv.nl, I could take a look at it to see if I can give any further advice.
      Reply
  • Pedro February 12th, 2019 4:25 pm
    Dear friends,
    In software, if I set the type of analysis as "Citation", and the unit of analysis as "Authors", and set up the "Overlay Visualization", I will have an authors' network. I can set, as example, the scale of circles as proportional to the number of documents as the weight and the Avg. pub. of year as the score. Thus, about the total link strength: it will indicate the frequency that the authors were cited together? Or it will be proportional to how they cite each other?
    Thanks!
    Reply
    • Ludo Waltman February 12th, 2019 7:01 pm
      For two authors A and B, the link strength equals the number of citatons given by A to B plus the number of citations given by B to A. The total link strength of an author A equals the sum of the link strengths of A with all other authors.
      Reply
      • Pedro February 12th, 2019 8:01 pm
        Thanks Ludo.
        Reply
  • Pablo Rodriguez February 12th, 2019 10:14 am
    Good morning, I'm trying to create a map following the steps:
    Create a map based on network data - Select files - Chose threshold -
    i have 250 items and in the Select items I choose all of them but when I create the map only about 10 items can be seen because they are all one above the other, I mean that all items are shown so close to each other that they supperimpose so I can see only about 10 of the 250.. and no clusters can be seen, only a lot of small circles of different colors all toguether one above the other only occuping about 5% of all the screen..
    I mean the screen all white and all the items colapsed toguether ocupping a very small part of the screen.. I've been trying to expand it somehow but can't find how to do it...
    Reply
    • Ludo Waltman February 12th, 2019 3:58 pm
      The best way to address this issue is by lowering the value of the repulsion parameter on the 'Analysis' tab. For most analyses, the default value of this parameter is 1. You could for instance lower the value to 0, -1, or -2.
      Reply
      • Pablo February 15th, 2019 10:59 am
        Thanks a lot Ludo it worked fine!!
        Reply
  • Pu Chen February 11th, 2019 7:57 am
    Dear inventor,
    Do you need to cite any specific article for freely using VOSviewer in a publication purpose?
    Sincerely,
    Pu
    Reply
    • Ludo Waltman February 12th, 2019 3:55 pm
      Thanks for asking. You don't need to cite anything. However, many researchers that use VOSviewer choose to cite the VOSviewer paper listed at the top of this page, or alternatively they cite the book chapter about VOSviewer that is also listed above.
      Reply
  • Mooyeon KIm February 5th, 2019 10:11 am
    Reply
  • Atefeh Zolfagharnasab February 2nd, 2019 7:33 am
    hello. I'm working on text mining project. data was exported from Mendeley on RIS format. I use "create a map based on text data". Before creating map step, when the list of words is displayed for selection, I need to have these words in a MS Word file to present them to expert to decide how to choose words. How can I do this?
    Reply
    • Ludo Waltman February 3rd, 2019 10:26 pm
      The list of terms can be exported by right-clicking on the list. A context menu will appear that offers an option to export the list of terms. Using this option, the terms will be exported in a text file that can be opened in for instance MS Word or MS Excel.
      Reply
      • Atefeh Zolfagharnasab February 4th, 2019 7:19 am
        Hello. Thank you all the same, I'll try with it.
        Reply
  • Andréia Anschau February 1st, 2019 4:24 pm
    Hi, I have doubts about the construction of the journal network map in which the scale in the “overlay visualization” in relation to the impact factor of the journal (as in Figure 3, page 11 of Manual for VOSviewer version 1.6.10). Until now I only obtain this map with the scale in relation to the year of publication. From what I understand, two documents are needed, for example the "journal_map.txt." and "journal_network_sparse.txt." templates. I get my data similar to the "journal_network_sparse.txt.", but I am doubtful about the data to be used for my "journal_map.txt." Is it necessary to use all the information contained in this template? I tried to use a "journal_map.txt." containing only the ID and score , however an error message appears in line 1 "error while reading VOSviewer network file (line 1): invalid ID”. The IDs I entered in my "journal_map.txt." were extracted from the last step of the 'Create Map' wizard, saving the links between terms and documents. Can you give me an orientation about this? Maybe send me a "journal map" model with only the information I need for this type of map or a spreadsheet data so I can visualize better
    Reply
    • Ludo Waltman February 3rd, 2019 11:33 pm
      Maps such as the one presented in the VOSviewer manual cannot easily be created. There is no easy way to create these maps based on data downloaded through the Web of Science online interface. The map presented in the manual was created based on data extracted from the in-house version of the Web of Science database available at CWTS. The impact factor data was obtained from this database. I am afraid this data cannot easily be obtained through the Web of Science online interface.
      Reply
  • Anton January 30th, 2019 9:50 am
    Hi Ludo,
    Really appreciate your wonderful work and the commitment to answering various queries.
    I have an unresolved issue in making the maps available online. I have followed the exact steps in the manual, however, when downloading and opening the files, i get an error: "Error ...: File cannot be found".
    I have made the map available to public via Google Drive as well as direct download. Neither require passwords. When clicking the link http://www.vosviewer.com/vosviewer.php?map=https://drive.google.com/uc?export=download&id=1OkIHGGHKpaRLxmNNqSnOE3e-a7dn3rp2&network=https://drive.google.com/uc?export=download&id=1z7KwAED28aO4qS-L5vYxMuC0OYZGOpsu the software says "Error ...: File cannot be found". However, the link (for the map) itself seems to work and download fine: https://drive.google.com/uc?export=download&id=1OkIHGGHKpaRLxmNNqSnOE3e-a7dn3rp2 (direct download link) or https://drive.google.com/open?id=1OkIHGGHKpaRLxmNNqSnOE3e-a7dn3rp2 to open with the browser. Alternatively, if i try to input the following address (without the direct download file): http://www.vosviewer.com/vosviewer.php?map=https://drive.google.com/open?id=1OkIHGGHKpaRLxmNNqSnOE3e-a7dn3rp2 it says: "Unable to create map: Incorrect use of quotes".
    I'm struggling with this issue for a while now, is there anything you could suggest, please?
    Kind regards,
    Anton
    Reply
    • Ludo Waltman February 3rd, 2019 11:38 pm
      This problem can be solved by replacing the ampersands after ‘download’ by the code ‘%26’.
      Reply
      • Anton February 4th, 2019 7:52 am
        Ludo, you are a legend. Thank you, so much!
        Reply
  • Andy Yeung January 24th, 2019 10:39 am
    Hi everyone, is it possible to select some bubbles not to be visualized, by altering the files of map.txt and network.txt. My computer spent a long time to digest the large dataset and generate the term map / keyword map, so I do not want to re-run the processes again just to remove bubbles that are not relevant for my visualization purpose.
    Reply
    • Ludo Waltman January 24th, 2019 6:20 pm
      Yes, this is possible. You simply need to remove the relevant lines from the map file. The lines in the network file that point to the items to be excluded from the visualization need to be removed as well.
      Reply
  • MURENDENI LIPHADZI January 16th, 2019 9:36 am
    I can seem to run vosviewer on my mac..i get a message saying unable to run java run time environment everytime i open the application. please help
    Reply
    • Rafael L February 15th, 2019 11:01 pm
      I'm getting the same error message. Have you found out the solution?
      Reply
  • Raquel Reis January 14th, 2019 1:29 pm
    I have a network database in pajek format, but I'm having trouble importing it into VOSviewer. The problem is that when I import the file containing the clusters, the error appears that there is no identification of the vertices. I would like to know how the base format should be (what it should contain in rows and columns) so that the program can read my base in pajek or excel format. I did not find this information in the manual.
    Reply
    • Ludo Waltman January 14th, 2019 4:22 pm
      Could you please send your files to vosviewer@cwts.leidenuniv.nl, so that we can take a further look at your problem?
      Reply
  • Philip December 24th, 2018 11:01 pm
    When I run citation analysis, the results seem to be unstable.
    Please advise:: Should the results with respect to citation totals differ depending on the thresholds?
    I would think that total citations should be a stable total if one is using the same database.
    Philip
    Reply
    • Ludo Waltman December 24th, 2018 11:45 pm
      Could you please provide a bit more details: Which type of citation analysis did you carry out (i.e., citations, bibliographic coupling, co-citation)? What is your unit of analysis (e.g., documents, sources, authors)? What do you mean by 'citation totals'?
      Reply
      • Philip December 24th, 2018 11:51 pm
        Sorry!
        Citation analysis of authors and citation of documents Total citations.
        When I rerun the anal.ysis at different times, I get slightly different rank order and some different citation results. I thought I was using the same settings, but I didnt thing the number of citations would change with the settings.
        Reply
        • Ludo Waltman December 24th, 2018 11:54 pm
          What do you mean by 'citation of documents Total citations'?
          Reply
          • Philip January 30th, 2019 7:45 am
            Sorry for the delay in responding. I am running "citations of documents" on a database of 1,842 documents. I am using a thesaurus file.
            Case 1: When I set the minimum citation threshold at 1 or 2 citations, I get a list in which the top cited docs are 250/189/181.
            Case 2: When I set the minimum citation threshold at 3, 4, 5, or 6, I get a list in which the top cited docs are 522, 250/189/181 (doc with 522 is a new doc which did not appear in Case 1).
            Case 3: When I set the minimum citation threshold at 7 citations and higher, I get a list in which the top cited docs are 522, 250/250/189/181 (2nd doc with 250 is a new doc which did not appear in Case 1 or 2).
            I have run into this kind of problem before. I used to assume it was my error and just kept changing my tables. However, it is something that seems to happen frequently.
            What am I missing here?
            Reply
            • Ludo Waltman January 30th, 2019 10:55 am
              There are two types of citation statistics in VOSviewer. On the one hand, there is the total number of citations a document has received in the entire Web of Science database (or whatever database is used). On the other hand, there is the number of citation links a document has within the current data set provided as input to VOSviewer. I think the distinction between these two concepts is causing confusion. When you set a threshold based on the number of citations of a document, this threshold applies to the total number of citations received in Web of Science. When you look at the number of citation links of a document, this is the number of links within the current data set.
              Reply
  • Marina December 24th, 2018 5:08 pm
    Hello, I tried to open my files but an error returned
    "Error while reading web of science file..... is not a valid column header" What I did wrong?
    Reply
  • Andy Yeung December 23rd, 2018 3:53 pm
    Thanks for developing the software and updating it from time to time. At times I opened the map.txt for term map, and did notice that the Occurrence count was smaller than the number returned by WoS on manual search. Same situation applied to map.txt for citation map of Organization or Country. Is it because VOSviewer would discard some records with missing info, e.g. those without abstract?
    On the other hand, would it be possible to add a function that can list the documents responsible for the specific terms displayed in the term map? Or at least to give 95% confidence intervals for the averaged citation count data. Because the colored bubble maps are very eye catching, but reviewers and readers may want to know if the colors are stable (with small 95% C.I.) or influenced by outliers. Thanks for your attention.
    Best,
    Andy
    Reply
    • Ludo Waltman December 23rd, 2018 4:06 pm
      In the final step of the 'Create Map' wizard, a table is presented listing the items (e.g., terms, organizations, or countries) that will be included in your map. It is possible to right-click on this table. A context menu will then appear that offers an option to export the links between the items and the documents in which the items occur. By exporting these links, you know for each item the underlying documents, making it is possible to answer questions such as the ones you have.
      By the way, VOSviewer does not discard any documents. In the case of organizations and countries, I am not sure why statistics reported by WoS differ from those reported by VOSviewer. In the case of terms, this might be due to the way in which term occurrences are counted by VOSviewer. For instance, if a term 'neural network' occurs in a document, VOSviewer will count this as an occurrence of 'neural network', not as an occurrence of 'network'. This might explain the difference between statistics provided by WoS and VOSviewer.
      Reply
  • Pablo Rodriguez December 8th, 2018 11:40 am
    Thanks a lot for this incredible tool! I just wanted to ask if is possible to export the items after clusters are generated, in the Items tab we can see for each cluster the items that conform them, is possible to export such list of items?
    Also similarly, when we create the map for example "create a map based on network data" then I select the map file and the network file, then I have to chose the total link strength of an item and at last there is a list of all items and their respective strengths, is possible to export or select or copy that list of items with their strenghts?
    Because I think it is important to show the strenght of each item as a measure of the "quality" of the item, if I understand it right the larger the strength the more important is the selected item.
    Thanks again for your great work
    Best regards
    Pablo
    Reply
    • Ludo Waltman December 8th, 2018 12:28 pm
      When you save a map in a VOSviewer map file, the information that you are looking for can be found in this file. A map file is a plain text file with tab-delimited columns. It can best be opened using a spreadsheet program such as MS Excel.
      Reply
  • giuseppe vito November 19th, 2018 10:25 am
    Dear Ludo, dear Philip H., I had encountered the problem having already worked uncheking FOUNDING DETAILS and "Tradenames & manufacturers" and "Accession numbers & chemicals" in the section OTHER INFORMATION. Uncheking in BIBLIOGRAPHIC INFORMATION everything except "Affiliations" and "EID", "Access Type" and "Author (s) s ID" in the section CITATION INFORMATION, everything works for the purpose of my work. The consistency remains in the fact that with the same restrictions on the export of metadata, some subsets of a research on Scopus that is treated by Vosviewer without problems, are not read by the program. I hope to have contributed to the issue, also suggesting something to the Scopus team. Best regards
    Reply
  • giuseppe vito November 18th, 2018 6:05 pm
    Dear Ludo, here I am again:
    a csv file from Scopus obtained with the query (SRCTITLE (sustainability) AND AFFILCOUNTRY (italy)) AND (LIMIT-TO (DOCTYPE, "ar")) returns 900 refs. [of which 42 contain the keyword "climate change"] and Vosviewer treats it without problems.
    By limiting the search in these 900 docs to the exact keyword "climate change" with the query
    (SRCTITLE (sustainability) AND AFFILCOUNTRY (italy)) AND (LIMIT-TO (DOCTYPE, "ar")) AND (LIMIT-TO (EXACT KEYWORD, "Climate Change")) Scopus returns the csv file containing 42 refs but Vosviewer fails to read it by returning the error "... incorrect number of columns". The fact amazes me because this second file should be (is) a subset of the first. Can you kindly help me?
    Reply
    • Ludo Waltman November 18th, 2018 6:35 pm
      This is indeed very strange, but I am afraid I cannot help with this. There currently is a problem with the Scopus CSV export. The nature of the problem is not entirely clear to me. The problem needs to be fixed by Elsevier's Scopus team. Hopefully they will do so as soon as possible. There is not much I can do at the moment.
      Reply
      • giuseppe vito November 18th, 2018 6:48 pm
        Dear Ludo, thank you all the same, I'll try with Web of Science. Good Sunday evening
        Reply
        • Philip H. November 18th, 2018 11:24 pm
          Please that the workaround offered previously by another contributor here DOES WORK. In the selections under CSV Export UNCHECK the box next to FUNDING DETAILS. Then try to export and upload.
          It has worked for me even after I ran into the same exact problem.
          Reply
      • Maryam Mazaheri November 23rd, 2018 11:24 pm
        Ludo Waltman
        As i had the same problem with scopus, i try publish or perish software and the Csv. result File that the software get is shown in vosviewer.
        Reply
  • Nikhil November 16th, 2018 12:50 pm
    Hello everyone, Can someone please clarify?
    When I create a co-citation(cited references) map, a particular node has following information:
    Item: graham Jr, 2005, i account econ
    cluster: 3
    links: 215
    total link strength: 739
    citations: 47
    If I understood correct this node has 215 links with different nodes in the map and the sum of strengths of all links is 739. But what is do this 215 links actually show? is it no of co-citations? if not how can I find no of co-citations?
    Thank you in Advance
    Nikhil
    Reply
    • Ludo Waltman November 16th, 2018 10:58 pm
      When you move the mouse over a co-citation link, you can see the strength of the link in the status bar. The strength of the link equals the number of co-citations of two cited references.
      Reply
      • Philip H. November 17th, 2018 2:12 am
        Ludo
        Could you please clarify this point further concerning 'strength of links'.
        - I had thought that the lines 'linking' two nodes on a citation map (e.g., documents) were indications of the number of times a document had been CITED BY ANOTHER DOCUMENT.
        - I had thought that the proximity of two nodes were an indication of how frequently two documents had been co-cited.
        Based on these assumptions, I wrote in a ms. the following: "Density of 'links' connecting two scholars reflect the number of times a scholar has been co-cited by another scholar."
        I guess I am confused!
        Please reduce my confusion! :)
        Reply
        • Ludo Waltman November 17th, 2018 9:18 am
          The proximity of two documents indeed is an indication of how frequently the documents have been co-cited. A link also represents the frequency of co-citation of two documents. It does not represent the number a times a document has been cited by another document. The expression 'co-cited by another scholar' should have been 'co-cited with another scholar'. I hope this offers some clarification!
          Reply
          • Philip H. November 17th, 2018 11:17 am
            Therefore, 'denser links' between two scholars would indicate higher co-citation of their work by other scholars. Your explanation leads to 2 follow-up questions.
            1. If proximity of authors and the number of links between two authors BOTH reflect the degree of co-citation, then why are some authors with many links far away from each other on the map?
            2. Does any info provided in the map offer an indication of 'which scholars' are frequently co-citing other scholars?
            Thanks. Your prompt and clear feedback is really appreciated by all of us users of VOSviewer.
            Reply
            • Ludo Waltman November 17th, 2018 12:30 pm
              1. There are two reasons for this. First, only two dimensions are available for the visualization. A high-dimensional data set therefore needs to be projected into two dimensions. This means that the data set cannot be represented in a perfectly accurate way. For this reason, strongly linked items are sometimes located far away from each other. Second, the distance between two items in fact indicates the strength of the relation between the items after normalizing for the fact that some items (e.g., authors with many publications) tend to have stronger relations than others (e.g., authors with just a few publications). The normalization is selected on the 'Analysis' tab in VOSviewer. The default normalization is the so-called association strength. It is also possible to turn off the normalization.
              2. No, this information is not provided. However, the map does show which authors are frequently co-cited with other authors. These are the authors with a high total link strength. They have a large size in the map, so they are prominently visible.
              Reply
      • Nikhil November 17th, 2018 12:36 pm
        Thank you for your reply.
        Reply
  • Pedro November 13th, 2018 6:22 pm
    Hey Waltman. How are you?
    I'm trying to use the VOSVIEWER for a survey paper. Nevertheless, I have a doubt about the Thesaurus file. Can you help me?
    So, as database papers, I send you this file from Scopus (it is a bit old and is not having problems as the recent files from Scopus database) . In this database, I have to replace some keywords, e.g. micro grids by microgrid; micro grid by microgrid, etc, as you can see in the file Thesaurus_1.
    On other hand, I have to standardize the name of an author: thorp, j by thorp, js, as you can see in the file thesaurus_authors.
    In both files, I think that I follow correctly your example of thesaurus files, however, when I try to generate the results, nothing happens. Can you point me where I'm wrong?
    Thank you in advance for your help, Mr. Waltman.
    I emailed you with my files.
    Reply
    • Ludo Waltman November 13th, 2018 6:57 pm
      You need to use the Scopus format for author names (rather than the Web of Science format). This for instance means that 'thorp, js' should be 'thorp j.s.'. This should solve your problem. If it doesn't, then please let me know.
      Reply
      • Pedro November 14th, 2018 1:22 am
        Thanks, Ludo!
        It is working now!!
        Reply
  • Ana Paula Ermel November 13th, 2018 12:46 pm
    I having a problem successfully uploading a Scopus data file. When I downloaded the data file of the Scopus (CSV), and upload in Voswier, gives an error message of an incorrect number of columns in row 276.
    Reply
    • Ludo Waltman November 13th, 2018 1:13 pm
      Unfortunately, there are currently problems with CSV files exported from Scopus. We are in contact with the Scopus team about this. They are investigating the issue. Hopefully, the problems will be fixed as soon as possible. As a workaround, you could consider using other data sources, such as Web of Science or Dimensions.
      Reply
      • Ana Paula Ermel November 13th, 2018 1:49 pm
        Thanks, Ludo!
        I'll be waiting.
        Reply
        • Ana Paula Ermel November 14th, 2018 12:56 am
          I just discovered that by unchecking the "Funding details" option when exporting the CSV file, VOSviewer runs it normally.
          Reply
  • Oloiva Sousa November 11th, 2018 9:36 pm
    Reply
  • Oloiva Sousa November 10th, 2018 8:38 pm
    i think that this application is excelent!
    Reply
  • Philip November 10th, 2018 10:49 am
    One of my doctoral students is having a problem successfully uploading a scopus data file. Although she did not have a problem in the past, when she updated the data file in scopus and downloaded again, VV gives an error message of an incorrect number of columns in row 276. her old file is still ok.
    We've tried exporting a fresh csv file, renaming the file, deleting a record and saving under a new name etc, but no luck. Any suggestions?
    Reply
    • Ludo Waltman November 10th, 2018 5:14 pm
      Could you please send your files to vosviewer@cwts.leidenuniv.nl? I will then take a look at your problem.
      Reply
  • Angel Bravo October 31st, 2018 8:09 pm
    Hi, would you tell me where I can find the thesaurus_authors.txt archive please
    Reply
    • Ludo Waltman November 1st, 2018 7:49 pm
      See the downloads available at www.vosviewer.com/download.
      Reply
  • Philip Hallinger October 30th, 2018 1:47 am
    Hi: I understand that the overlay visualization in co-word analysis will reveal the 'research front' in the particular literature. I would assume that the research front for the current literature would be the last five or six years.
    1. Therefore, I don't understand why the default for a temporal overal in a review that extends from 1960 to 2018 only shows the research front for 2006-2014.
    2. Also when I try to adjust the years in the legend bar to be 2010 to 2018, all of the topics change to a darker color.
    What am I missing here?
    Reply
    • Ludo Waltman October 30th, 2018 7:24 am
      The colors show the average publication year of the articles in which a particular term occurs. These averages typically are located somewhere in the middle of your time period. It is unlikely that a term occurs exclusively in early years or exclusively in very recent years. This is why there will be hardly any terms in your data that have for instance 1965 or 2016 as their average publication year. In the case of your data, most terms apparently have an average publication year between 2006 and 2014, and the color scale is automatically adjusted to this.
      Reply
  • Ngan Kim Nguyen October 29th, 2018 12:07 pm
    Hi,
    Thank you so much for the useful and powerful tool for researchers.
    I have read the manual as well as watched some videos for instruction. However, I cannot find Information Panel even though I imitated almost the same steps from downloading data from Scopus to creating map for co-occurrence between terms. Any thing is alright except no Information Panel. I checked data on cvs file from Scopus, there is information of journals name. However, when I saved the map created by VOSviewer as map file, and checked that file, there is no Description column. I googled this case, but no information.
    I am very grateful if someone can instruct me what I should do to see the Information Panel.
    Best regards,
    Ngan
    Reply
    • Ludo Waltman October 29th, 2018 12:22 pm
      The information panel is available only when you have created a map of documents. Maps of other types of items do not make use of the information panel.
      Reply
  • Flavio October 20th, 2018 7:46 pm
    Dear all,
    I am performing on VOSviewer version 1.6.9 a co-authorship analysis of authors on Scopus bibliographic data. To avoid duplication of names (e.g., daly h. and daly he.), I created a thesaurus file following the example of the thesaurus_authors.txt file in the data folder, and then loaded it when the software asks me to.
    I created the thesaurus file on excel, saving it as a tab delimited file.
    Nonetheless, after running the analysis, results are the same to the analysis without the thesaurus file.
    Could you please give me some advice on how to make this work?
    Thank you very much for your help.
    Best,
    Flavio
    Reply
    • Ludo Waltman October 20th, 2018 8:42 pm
      Could you please send your files to vosviewer@cwts.leidenuniv.nl? I will then take a look at your problem.
      Reply
      • Flavio October 20th, 2018 8:55 pm
        I just sent the e-mail.
        Thank you very much!
        Best,
        Flavio
        Reply
  • PJH October 17th, 2018 1:17 am
    I am trying to understand the difference between the 'population of documents' on which citation and co-citation analysis are based.
    As I understand it, traditional citation analysis limits the population of citations to the database in which the citation analysis being conducted. Thus, we talk of Scopus citations or WoS citations etc.
    In contrast, co-citation analysis of documents is based of a 'broader reach' of documents. Thus, co-citation analysis conducted on a sample of studies drawn from SCOPUS will often yield documents that are not included in SCOPUS.
    MY QUESTION is what is the population of documents beyond Scopus (or Wos) that VOSviewer examines in order to generate co-citations?
    Co-citation analysis is new in my field and the journal reviewers are rightfully asking for detailed elaboration of the methodology.
    Thanks.
    Reply
    • Ludo Waltman October 17th, 2018 7:21 am
      You are right. Co-citation analysis considers a broader universe of documents than (direct) citation analysis and bibliographic coupling analysis. Co-citation analysis takes into account the references of documents indexed in databases such as Web of Science and Scopus. Hence, unlike citation analysis and bibliographic coupling analysis, co-citation analysis takes into account documents that are not themselves indexed in one's database but that are cited by documents that are indexed in the database.
      Reply
  • Antoine October 15th, 2018 10:52 am
    Amazing software! Thanks for the hard work!
    Is it possible to extract and export the publications belonging to each item and cluster?
    Antoine
    Reply
    • Ludo Waltman October 15th, 2018 3:16 pm
      What kind of map do you have? For instance, do you have a term map, a co-authorship map, or a citation-based map, and what is the unit of analysis in your map (e.g., authors, journals, etc.)?
      Reply
  • Anton October 4th, 2018 8:02 am
    Dear developers,
    Thank you for your wonderful software, it makes life much easier for researchers! I have a small query in regards to making the maps available online, section 5.2. I have followed the exact steps, however, when downloading and opening the files, i get an error: "Error while reading VOSviewer map file (line 1): Column header is empty". I used Google Drive, Box, free online file sharing websites, with the same error. This is a map example that i have: https://ecu.box.com/s/q6l9syr9s6l4rswjt4jydi18qy3w1ztr
    This is one of the ways i tried to make it available online (without the network map, which i also tried with the same error) to no avail.
    http://www.vosviewer.com/vosviewer.php?map=https://ecu.box.com/s/q6l9syr9s6l4rswjt4jydi18qy3w1ztr
    Please let me know what i have done wrong.
    Kind regards,
    Anton
    Reply
    • Ludo Waltman October 4th, 2018 11:46 am
      I have tried out the URL. I am unable to access the map file. It turns out that a log in is required. This is why VOSviewer is unable to read the map file and why you get an error.
      Reply
      • Anton December 4th, 2018 6:20 am
        Hi Ludo,
        I have tried different options to no avail. For example, I have made the map available to public via Google Drive as well as direct download. Neither require passwords. When clicking the link http://www.vosviewer.com/vosviewer.php?map=https://drive.google.com/uc?export=download&id=13hry4xag9tPG2Y_BMfxMaH7uvnKJS1pQ&network=https://drive.google.com/uc?export=download&id=1zPr10A2ajwPD_seuhAeBbHcGKVAxvBJL the software says "Error ...: File cannot be found". However, the link (for the map) itself seems to work and download fine: https://drive.google.com/open?id=13hry4xag9tPG2Y_BMfxMaH7uvnKJS1pQ (direct download link) or https://drive.google.com/uc?export=download&id=13hry4xag9tPG2Y_BMfxMaH7uvnKJS1pQ. Any comments are greatly appreciated.
        Kind regards,
        Anton
        Reply
  • Peter LR September 28th, 2018 9:42 am
    Hi! Congratulations for your work.
    I wonder if it is possible to export a list of the items by cluster.
    Thank you so much!
    Reply
    • Peter LR September 28th, 2018 10:48 am
      I've just realized I can find the information in map files.
      Thank you!
      Reply
  • John Paul SanGio September 20th, 2018 4:55 pm
    Thank you for offering this excellent resource.
    I am constructing a co-authorship map.
    I would like to display all authors with whom I have ever published.
    My current map (generated by default settings) contains only those authors with whom I have published a number of times.
    I would appreciate guidance on how to display all co-authors.
    John Paul
    Reply
    • John Paul SanGio September 20th, 2018 8:34 pm
      VOSviewer Staff:
      I solved the problem (found the options with the Web of Science input format).
      There is no need to respond.
      John Paul
      Reply
  • Ana September 11th, 2018 12:42 am
    Good night,
    Could you please explain me the meaning of "total link strength"?
    I am using VosViewer to do a co-citation analysis (cited references) and a column named "total link strength" appears (next to citation) ???
    Thank you very much!
    Best regards.
    Reply
    • Ludo Waltman September 11th, 2018 7:30 am
      This is explained in Chapter 2 of the VOSviewer manual. If this explanation is insufficient, then please let me know.
      Reply
      • Ana September 11th, 2018 10:40 am
        Hello Ludo,
        Thank you for your answer!
        I already had the Vosviewer manual, but I was asking because in the manual it refers to:
        bibliographic coupling links
        co-authorship links, and
        co-occurrence links

        But it is not clear to me in the case of co-citations (refrerences), whats the meaning of "total link strenght"

        Hoping you me can help me.

        Thanks a lot!
        Regards.
        Reply
        • Ana September 11th, 2018 6:49 pm
          Thanks for everything. I found the information!
          Greetings.
          Reply
      • Maurício November 11th, 2018 3:55 pm
        Hello!
        But how the total link strength is calculated? I research in the manual but I didn't found this information!
        Best regards
        Reply
        • Ludo Waltman November 11th, 2018 7:20 pm
          A brief explanation is provided on p. 5 in the VOSviewer manual:
          "There are two standard weight attributes, referred to as the Links attribute and the Total link strength attribute. For a given item, the Links and Total link strength attributes indicate, respectively, the number of links of an item with other items and the total strength of the links of an item with other items. For example, in the case of co-authorship links between researchers, the Links attribute indicates the number of co-authorship links of a given researcher with other researchers. The Total link strength attribute indicates the total strength of the co-authorship links of a given researcher with other researchers."
          In other words, in the case of co-authorship links, the Links attribute of a given researcher equals the number of researchers with whom the focal researcher has co-authored one or more publications. The Total link strength attribute of a given researcher equals the sum over all other researchers of the number of publications co-authored with the focal researcher. Definitions for other types of links (citation, bibliographic coupling, co-citation, co-occurrence) are analogous.
          Reply
          • Mauricio November 18th, 2018 9:38 pm
            Thanks Ludo
            Now I understand. In the manual it wasn't so clear.
            Best Regards!!
            Reply
  • Breno Prata September 9th, 2018 4:31 am
    Good night,
    I am trying to create a web integration between VOSViewer and Gephi, I want it all to work as simple as possible, I want to import a csv file from scopus into VOSViewer and generate a map, after that export that map to a supported Gephi format. But I can't quite find that code on the JAR source file, is that any way to help me find those specific code, it would really make a diference if I managed to unite these two tools :)
    Reply
    • Ludo Waltman September 9th, 2018 9:03 am
      The source code of VOSviewer currently is not available. The software is not open source. We plan to release the source code within the coming months.
      Reply
  • Hai Giang Ha September 7th, 2018 9:44 am
    Dear Mr. Ludo Waltman,
    Could you please tell me how I can explain the relationship of items in a cluster? How was the color of a cluster assigned? And Is there anyway if I want to change the position of one item?
    I need that information to explain in my report.
    Thank you so much and I am looking forward to hearing from you.
    Best regards,
    Hai Giang Ha
    Reply
    • Ludo Waltman September 7th, 2018 7:25 pm
      Your question is a bit general. Some answers are provided in the VOSviewer manual and in the book chapter available above. If these answers are insufficient, then please let me know.
      Reply
  • Philip Hallinger August 28th, 2018 5:32 pm
    Great program.
    I have not had any issues up to now. However when I upload a scopus file, I keep getting an error message that there is an incorrect number of rows in record 367. I went and deleted record 367 in scopus. Now it says the error is in record 368.
    What's the problem and the solution, please.
    Reply
    • Ludo Waltman August 29th, 2018 7:43 am
      Could you please send me your file (vosviewer@cwts.leidenuniv.nl)? I will then take a look at it and offer advice on this issue.
      Reply
      • Philip August 29th, 2018 8:19 am
        Ludo
        Thanks for the prompt response. Although I am an absolute newbie at this I found a workaround for the problem.
        The database was only 700+ documents, so I exported 200 at a time to 4 files and uploaded the four files. it worked. So although I don't know what the 'problem' actually was, I don't have it anymore and I'm a happy guy.
        So thanks again.
        Reply
  • Alberto August 23rd, 2018 10:22 am
    Hi! Thank you for your work on VOSviewer.
    I'm wondering if it is possible to create a co-citation keyword map based on a personal library of papers.... I mean, not taken from scopus or wos, but, for example, from a .bib file. Keywords are there, so I'm wondering if a way to do that actually exists.
    Thanks!!
    Alberto
    Reply
    • Alberto August 23rd, 2018 10:39 am
      I did it with .RIS file very easily from Endnote! Thanks!
      Reply
  • Robyn August 22nd, 2018 6:43 pm
    Hello, I'm working on cleaning up a small set of citations using a thesaurus file. I've reviewed the sample thesaurus files provided, and taken the suggestions in the comments made previously of creating a tab delimited file using Excel. However, when I create my visualization, instead of replacing the terms outlined in the thesaurus file, it simply removes them from the visualization altogether.
    It was my understanding that the "replace by" column would allow me to collect together the alternate spellings/ plurals into on term - not remove the terms entirely. Have I misinterpreted the purpose? Is there a strategy you would suggest to resolve this issue?
    Many thanks!
    Reply
    • Ludo Waltman August 22nd, 2018 9:59 pm
      Your interpretation is fully correct. Could you please send your thesaurus file to vosviewer@cwts.leidenuniv.nl? I will then take a look at the file and try to offer some advice.
      Reply
    • Alberto September 9th, 2018 9:50 pm
      Hi Robyn,
      could you please tell me where I can find the thesaurus samples?
      Thanks!
      Reply
    • Diana October 18th, 2018 4:46 pm
      Hello, Robyn. Would you succeed with your thesaurus? I am working with the same task. Could you share your Excel file to look how it is created?
      Thank you.
      Diana
      Reply
  • Giuseppe Vito August 19th, 2018 5:37 pm
    Dear Ludo,
    Thanks for the reply.
    The txt files I intend to make available on-line are those generated by Vosviewer in the analysis of bibliographic coupling, cocitation, etc. (... map.txt and ... net.txt) of publications of the department I belong (exactly as discussed in section 5.2 of the manual). Currently the aim is to divulge bibliometric maps to colleagues of the department, subsequently I intend to integrate some of my publications with links to the related Vosviewer maps.
    In the meantime I solved the problems with github, which constantly flagged my account by mistake: I'm sorry for the request made to you.
    On this occasion:
    using excel to read a file ... map.txt (eg. bibliocouplingmap.txt), the format of the individual cells of the columns weight and score is not unique and I cannot transform them into one numerical format as I would like to perform further reflections.
    is it possible to generate a network file in full format (pages 38-39 of the manual version 1.6.8) instead of sparse format?
    Thank you very much for the attention you will dedicate to me.
    Reply
    • Ludo Waltman August 19th, 2018 5:47 pm
      Your Excel problem probably relates to the regional settings of your operating system. The easiest way to solve the problem then is to change the regional settings. You need to make sure that a period, not a comma, is used as the decimal separator.
      Saving a network file in the full format is not supported by VOSviewer. VOSviewer can open network files in two formats, both the sparse and the full format, but it always saves these files in the sparse format.
      Reply
      • Giuseppe Vito August 19th, 2018 5:55 pm
        Thanks for the immediate reply, I will try to change the settings in Excel and I will let you know
        Reply
  • Giuseppe Vito August 16th, 2018 5:43 pm
    Dear Ludo and Nees Jan, first of all my congratulations for your work and my best wishes for future developments. I encounter problems in making txt files available online. I have used github but I am not fully satisfied with this software. Could you kindly suggest alternative ways of doing this? Best Regards. Giuseppe Vito, Parthenope University, Naples, Italy
    Reply
    • Ludo Waltman August 19th, 2018 1:23 pm
      I think I need a bit more information to answer your question: What kind of text files do you want to make available online, and for what purpose? Do you mean that you are trying to make a map available online, as discussed in Section 5.2 of the VOSviewer manual? And why exactly are you 'not fully satisfied' with GitHub?
      Reply
      • Giuseppe Vito August 19th, 2018 5:33 pm
        Dear Ludo,
        Thanks for the reply.
        The txt files I intend to make available on-line are those generated by Vosviewer in the analysis of bibliographic coupling, cocitation, etc. (... map.txt and ... net.txt) of publications of the department I belong (exactly as discussed in section 5.2 of the manual). Currently the aim is to divulge bibliometric maps to colleagues of the department, subsequently I intend to integrate some of my publications with links to the related Vosviewer maps.
        In the meantime I solved the problems with github, which constantly flagged my account by mistake: I'm sorry for the request made to you.
        On this occasion:
        1) using excel to read a file ... map.txt (eg. bibliocouplingmap.txt), the format of the individual cells of the columns "weight " and "score " is not unique and I cannot transform them into one numerical format as I would like to perform further reflections.
        2) is it possible to generate a network file in full format (pages 38-39 of the manual version 1.6.8) instead of sparse format?
        Thank you very much for the attention you will dedicate to me.
        Reply
  • Fernanda August 13th, 2018 5:18 am
    I am trying to download the VOSviewer for windows at this site. Althoug, my computer detected a virus
    The name is Trojan:Win32/Vigorf.A
    Is it safe to make the download here?
    Is there any problem with the website?
    Tkx
    Reply
    • Ludo Waltman August 13th, 2018 1:24 pm
      A number of VOSviewer users have reported this problem. We have investigated the problem in detail. The software is safe, and the threat warning given by Windows Defender is incorrect. We have added a brief explanation on the Home page and also on the Download page.
      Reply
      • Ludo Waltman August 19th, 2018 1:24 pm
        We have been in contact with Microsoft's Windows Defender team and the problem has now been solved.
        Reply
  • Ranbir August 10th, 2018 11:58 am
    Dear Friends
    If anybody can help me to answer
    Out of ---first author co-citation data and all-author co-citation data, which one is used by VOSviewer ?
    Your advice can very helpful for me
    Reply
    • Ludo Waltman August 10th, 2018 12:11 pm
      In the case of Web of Science data, only the first author is considered (since information on other authors is not available in Web of Science data). In the case of Scopus data, all authors are considered.
      Reply
      • Ranbir August 10th, 2018 12:39 pm
        Thanks a lot Dear Ludo Waltman
        Thanks again
        Reply
  • Anthony Molisani July 26th, 2018 5:45 pm
    Hi Dr Waltman,
    I really appreciate the text mining features of VOSviewer, In doing the analysis, I would like to further explore the publication metrics associated with the clusters of words. To do this, I need to know which publications are associated with each term. I'm having trouble finding such a way to identify/export theses relationships between publications-mapped terms. Any advice would be incredibly helpful!
    Reply
    • Ludo Waltman July 26th, 2018 6:16 pm
      In the last step of the 'Create Map' wizard, a table is presented that shows the terms that will be included in your term map. It is possible to right-click on this table. A context menu will then appear that offers the possibility to save the links between terms and documents. This seems to be exactly what you are looking for. Let me know if you need further information.
      Reply
      • Anthony Molisani July 26th, 2018 7:50 pm
        Hi Dr Waltman,
        That is perfect. Thank you!
        Regarding document id numbers, I imagine they are assigned based on the row within the upload document. How are they assigned when using multiple files when uploading records into VOSviewer?
        Thanks, again. This is extremely helpful!
        Reply
        • Ludo Waltman July 26th, 2018 8:00 pm
          When you have multiple input files, the document IDs are dependent on the order in which your files are processed by VOSviewer, and this order is not visible to the user. In this case, it is therefore best to manually merge your files into a single input file. The document IDs then correspond in an unambiguous way to rows within your input file. Note that, if your input file includes a header line (as is the case for Web of Science and Scopus files), the first document is located on the second line in your file and the ID of this document is 1. The document on the third line has ID 2, and so on.
          Reply
          • Anthony Molisani July 26th, 2018 9:06 pm
            Excellent. Thank you very much!
            Reply
  • Hai Giang Ha July 15th, 2018 12:17 pm
    Dear Mr. Waltman,
    I am now using this wonderful tool for bibliometric analysis. The records download from the Web of Science are quite large, about 250,000 records. When I insert the records, the system informed that I need to extend the memory. I have read the manual, yet, I could not find VOSviewer JAR file as well as the command line.
    Could you please tell me where I can download the VOSviewer JAR file and the command line?
    I am looking forward to hearing from you.
    Thank you so much.
    Hai-Giang Ha
    Reply
    • Ludo Waltman July 15th, 2018 1:39 pm
      The JAR file can be downloaded from the VOSviewer website. It is referred to as the VOSviewer version for other systems (i.e., not for Windows or for Mac systems). In principle, the Windows and Mac versions of VOSviewer should already make use of most of the internal memory available on your system, so I am not sure whether the use of the JAR file will solve your problem. I am wondering what kind of map you would like to create based on your 250,000 records. If you could provide me with some more details, I may be able to offer some further advice. It would also be helpful for me to know you much internal memory you have available on your system. (By the way, the amount of internal memory that is made available to VOSviewer can be found in the bottom part of the 'About' dialog box in VOSviewer.)
      Reply
      • Hai Giang Ha July 15th, 2018 5:24 pm
        Thank you so much for your quick reply.
        The amount of internal memory that I found in the 'About" dialog box is 'Memory usage: 37/ 746 MB'.
        I want to create an (author) keywords co-occurrence and countries co-authorship network.
        Reply
        • Ludo Waltman July 15th, 2018 7:17 pm
          746 MB is a small amount of memory. This may cause problems even for data sets much smaller than yours. How much internal memory does your computer have in total? Do you have many other programs that are running simultaneously with VOSviewer?
          Reply
          • Hai Giang Ha July 16th, 2018 5:17 am
            I have installed VOSviewer on my other computer, driver D. Its volume is 537 GB, and it has 515 GB free. The system information: RAM 8GB. Memory usage this time somehow is better '44/ 989 MB'. However, I still can not create the maps with that 250,000 records. When I used VOSviewer, I closed almost programs but MS Word, MS Excel, and Chrome.
            Thank you
            Reply
            • Ludo Waltman July 16th, 2018 9:34 am
              Thanks for the additional information. Based on this information, it seems that you are probably working with a 32-bit version of Java. In order to get access to more internal memory, you need to use a 64-bit version of Java. This means that you need to update Java on your system,. My recommendation is to update to the most recent 64-bit version of Java 8. (Do not use Java 9 or 10.)
              Reply
              • Hai Giang Ha July 19th, 2018 10:57 am
                Thank you so much for your suggestion.
                After reinstalling Java 8 64-bit for Window, it really worked. When I checked "About", it stated "Memory usage: 109/4132MB". I uploaded the 250,000 records, it loaded 99% and then stopped (before it was only 32%).
                Do you have any solution for me?
                Reply
                • Ludo Waltman July 19th, 2018 11:49 am
                  I am glad to hear that 64-bit Java works better. It seems that you still don't have enough memory to process such a large data set. I think you need to either reduce the size of your data set or find a computer with more internal memory. I hope this is possible for you.
                  Reply
                  • Hai Giang Ha July 22nd, 2018 8:08 pm
                    Thank you for spending your precious time to help me.
                    I install VOSviewer on other computer and it worked.
                    I do appreciate what you and your team have done for the global scientific research.
                    Reply
  • Fatima Noora July 6th, 2018 8:55 pm
    Dear Mr Waltman,
    Could you kindly advise on the way to create Thesaurus file? (the simplest possible, please)
    I am stuck because of the many synonyms, spelling differences and abbreviated terms I've in my Scopus data base.
    Thanks in advance,
    Fatima
    Reply
    • Ludo Waltman July 6th, 2018 11:07 pm
      When you download VOSviewer, you will obtain a ZIP file that includes two examples of thesaurus files. Please take a look at these examples. Let me know if you have any questions based on these examples.
      Reply
      • Fatima Noora July 6th, 2018 11:12 pm
        I already did! they are terms and authors.
        My question is how to create a file like this?
        Reply
        • Ludo Waltman July 6th, 2018 11:22 pm
          It is easiest to create such a file using a spreadsheet program, for instance MS Excel. Make sure to save your thesaurus as a tab-delimited text file.
          Reply
          • Fatima Noora July 6th, 2018 11:48 pm
            Well noted!
            Thank you so much.
            Reply
  • William Sanger July 5th, 2018 7:23 pm
    Hi M. Waltman,
    First of all, thanks for such amazing tool VOSviewer is. I've been using it for the past 2 years to visualize batchs of academic papers, which was great.
    I have a question. I cannot do usual visualizations with VOSviewer using Web of Science exportation tool (5K). Now, when I export papers, it only shows the title, the author and the source. I do not have access to the keywords anymore. The same goes with "save to other file formats".
    Do you have any insight about such situation? If so, do you know any alternative?
    Best regards, and thanks a lot again,
    William
    Reply
    • Ludo Waltman July 5th, 2018 7:35 pm
      Using the 5K option, files exported from Web of Science do not provide full publication records. To obtain full publication records, you need to use the ordinary export feature of Web of Science, where downloads need to be done in batches of at most 500 records. I am afraid this is the only solution. When you use the ordinary export feature of Web of Science, it is possible to download full publication records. VOsviewer will then be able to create keyword co-occurrence maps and other types of maps that cannot be created based on incomplete publication records.
      Reply
      • William Sanger July 9th, 2018 2:53 pm
        Thanks a lot,
        Have a great day,
        W.
        Reply
  • Shivam June 28th, 2018 8:59 pm
    Dear Sir,
    can a VOS viewer be done for the Data downloaded from google scholar using publish and perish tool in csv format ?
    or what other methods can be used to do an analysis for google scholar data ?
    Reply
    • Ludo Waltman June 28th, 2018 10:06 pm
      Yes, it is possible to work with Google Scholar data in VOSviewer. This can be done by downloading data from Google Scholar using Publish or Perish and by saving the data in a RIS file. Unfortunately, the possibilities for analyzing Google Scholar data in VOSviewer are limited. In particular, it is not possible to create citation-based maps based on Google Scholar data.
      Reply
  • Ilenia June 26th, 2018 7:25 pm
    Hello,
    I would like to use VosViewer for my research, however I am having issues in uploading files from Scopus.
    I did my research on scopus and I exported in a CSV file all information that Scopus allows me to export i.e. citation, bibliographic information, etc. When I open the downloaded file I can see all the details of the papers I selected in my search. When I upload the file in VosViewer and I try to create a term map VosViewer displays this message: "Error while reading Scopus file: file is empty". I do not understand what is the problem since I have not changed anything in the downloaded file. Could you please help me with this issue?
    I thank you in advance.
    Best regards,
    Ilenia
    Reply
    • Ludo Waltman June 26th, 2018 10:20 pm
      Could you please send your file to vosviewer@cwts.leidenuniv.nl? I will then take a look at your problem.
      Reply
      • Ilenia June 27th, 2018 1:10 am
        Hi Ludo,
        I thank you for your reply but it seems that I sorted out the problem. I had to make sure that the content in the first cell of the first row was split in different colomns. Once that I did this, the software is now working.
        Best regards,
        Ilenia
        Reply
  • Jasmijn June 25th, 2018 1:55 pm
    Hi there,
    Could you give me some advice on the following?
    I learned about VOSviewer through a colleague and wonder whether the software is suitable for a literature review I'm currently conducting:
    After a systematic search I've ended up with a small dataset of 45 suitable references. I notice an immense range of operationalizations for the same concept that are used by these references and want to delve further into this issue. I want to visualize the different measurements, group them and show how many references use the same measurement. I think there are several islands of measurements that are used by the same authors and I would like to map this. I then would like to see whether the references cite each other and how many references build bridges to other islands of measurements.
    Would it be possible to create the network maps I'm looking for in VOSviewer or does the software only produce maps based on references as data? I guess that my research interests would require me to create and import data (measurements) that I would have to construct myself. Based on what I read on VOSviewer so far, I am not certain whether the software is suitable for this specific literature review.
    Thank you very much for considering my request.
    Best wishes, Jasmijn
    Reply
    • Ludo Waltman June 25th, 2018 6:38 pm
      Although I don't fully understand what kind of visualization you would like to create, I do think it is possible to create such a visualization using VOSviewer. However, this will require an in-depth knowledge of VOSviewer, since you will need to do considerable preprocessing of your data to provide the data to VOSviewer in the right way. If you do not yet have a substantial experience in working with VOSviewer, then I think creating the visualization you have in mind will be quite challenging.
      Reply
      • Jasmijn June 26th, 2018 10:23 am
        Thank you very much for your swift reply! This is helpful in deciding what to do. Best wishes, Jasmijn
        Reply
  • Lara June 23rd, 2018 12:32 am
    Hi there,
    I've been using VOSViewer for a couple of years now, and I really like what you can do with it. However, I find myself unable to use it for graphic analyses of co-citations (i.e., nb of times specific papers get cited in a series of references). I've tried to upload databases with .RIS and .CSV extensions but I can't seem to get it right: I never get the option to analyse co-citations (only co-authorship and co-occurences). What is the right format to run a bibliomeric analysis of co-citations? If the source should be .CSV, what should my table look like?
    Thanks for your advice,
    Lara
    Reply
    • Ludo Waltman June 23rd, 2018 12:42 am
      Citation-based analyses indeed are not supported for RIS files. This is because RIS files do not contain reference data in a standardized format. Citation-based analyses are supported only for Web of Science files, Scopus CSV files, and Crossref JSON files.
      Reply
      • Lara June 23rd, 2018 12:51 am
        Thanks a lot for your prompt response! Ok, it makes sense. However, none of these research databases (WoS, Scopus and Crossref) provides the exact list of refs. Is it possible to build the file manually? Is there a sample I can follow?
        Reply
        • Ludo Waltman June 23rd, 2018 7:43 am
          I am not entirely sure what you mean by "none of these research databases (WoS, Scopus and Crossref) provides the exact list of refs". What do you mean by "the exact list of refs"? Anyway, in order to have an example, just download a file from Web of Science or Scopus and use that file as an example. Please keep in mind that you need to follow exactly the file format used by Web of Science or Scopus, including the format used for specifying references. Otherwise VOSviewer will not be able to process your data.
          Reply
          • Lara June 23rd, 2018 4:13 pm
            Ok, noted. Thank you for your help!
            Reply
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