Ludo Waltman

Biographic Data

ID4972739
NAMELudo Waltman
GIVEN NAMESLudo
FAMILY NAMEWaltman
SIGNATUREWALTMAN L
AFFILIATIONSLeiden University
ORCID0000-0001-8249-1752
VERIFIEDYes
TOTAL WORKS30
TOTAL CITATIONS458
AUTHOR COUNT30
EDITOR COUNT0
FIRST PUBLICATION YEAR2009
LATEST PUBLICATION YEAR2025
H-INDEX1

  • Which topics are best represented by science maps? An analysis of clustering effectiveness for citation and text similarity networks

    Open AccessJuan Pablo Bascur, Suzan Verberne et al.ARTICLEScientometrics2025

    A science map of topics is a visualization that shows topics identified algorithmically based on the bibliographic metadata of scientific publications. In practice not all topics are well represented in a science map. We analyzed how effectively different topics are represented in science maps created by clustering biomedical publications. To achieve this, we investigated which topic categories, obtained from MeSH terms, are better represented in…

  • A comparison of citation-based clustering and topic modeling for science mapping

    Open AccessQianqian Xie, Ludo WaltmanARTICLEScientometrics2025

    Understanding the different ways in which different science mapping approaches capture the structure of scientific fields is critical. This paper presents a comparative analysis of two commonly used approaches, topic modeling (TM) and citation-based clustering (CC), to assess their respective strengths, weaknesses, and the characteristics of their results. We compare the two approaches using cluster-to-topic and topic-to-cluster mappings based on…

  • Guidance for the reporting of bibliometric analyses

    Open AccessJeremy Y Ng, Henry Liu et al.ARTICLEQuantitative Science Studies2025

    Despite the growth in the number of bibliometric analyses published in the peer-reviewed literature, few articles provide guidance on methods and reporting to ensure reliability, robustness, and reproducibility. Consequently, the quality of reporting in existing bibliometric studies varies greatly. In response, we are developing a preliminary Guidance List for the repOrting of Bibliometric AnaLyses (GLOBAL), a reporting guideline for bibliometric…

  • Incentivising, excluding, and enduring

    Open AccessEleonora Dagienė, Vincent Larivière et al.ARTICLEScience and Public Policy2025

    Performance-based funding systems (PBFSs) are widely used to steer national research, but their effects vary significantly, particularly in countries with emerging research ecosystems. Relatively little attention has been paid to PBFSs and their concomitant policy dynamics in these countries, where the pressure to internationalise creates unique challenges. This paper presents a detailed study of the development of the Lithuanian PBFS from 2005 t…

  • Multi-actor Policy Dynamics in Research Evaluation

    Open AccessEleonora Dagienė, Ludo Waltman et al.ARTICLEHigher Education Policy2025References: 5

  • Making problems

    Open AccessDavid Moats, Tjitske Holtrop et al.ARTICLEScience as Culture2025References: 18

    Effective Protection of Fundamental Rights in a pluralist world

  • Academic information retrieval using citation clusters

    Open AccessJuan Pablo Bascur, Suzan Verberne et al.ARTICLEScientometrics2023

    The field of science mapping has shown the power of citation-based clusters for literature analysis, yet this technique has barely been used for information retrieval tasks. This work evaluates the performance of citation-based clusters for information retrieval tasks. We simulated a search process with a tree hierarchy of clusters and a cluster selection algorithm. We evaluated the task of finding the relevant documents for 25 systematic reviews…

  • Funding Covid-19 research

    Open AccessAlexis-Michel Mugabushaka, Nees Jan van Eck et al.ARTICLEQuantitative Science Studies2022

    To analyze the outcomes of the funding they provide, it is essential for funding agencies to be able to trace the publications resulting from their funding. We study the open availability of funding data in Crossref, focusing on funding data for publications that report research related to COVID-19. We also present a comparison with the funding data available in two proprietary bibliometric databases: Scopus and Web of Science. Our analysis revea…

  • The challenges of scientometric studies of predatory publishing

    Open AccessLudo Waltman, Vincent LarivièreARTICLEQuantitative Science Studies2022

    This issue of Quantitative Science Studies features the article “Predatory publishing in Scopus: Evidence on cross-country differences,” coauthored by Vít Macháček and Martin Srholec. Based on the Scopus database, this article studies how likely different countries are to publish in so-called predatory journals. Journals suspected to be predatory are identified using the well-known (and controversial) list of potentially predatory publishers and …

  • Understanding gender differences in science requires a diversity of perspectives, including controversial ones

    Open AccessLudo WaltmanARTICLEQuantitative Science Studies2021

  • Large-scale comparison of bibliographic data sources

    Open AccessMartijn Visser, Nees Jan van Eck et al.ARTICLEQuantitative Science Studies2021

    We present a large-scale comparison of five multidisciplinary bibliographic data sources: Scopus, Web of Science, Dimensions, Crossref, and Microsoft Academic. The comparison considers scientific documents from the period 2008–2017 covered by these data sources. Scopus is compared in a pairwise manner with each of the other data sources. We first analyze differences between the data sources in the coverage of documents, focusing for instance on d…

  • A multidimensional framework for characterizing the citation impact of scientific publications

    Open AccessYi Bu, Ludo Waltman et al.ARTICLEQuantitative Science Studies2021

    The citation impact of a scientific publication is usually seen as a one-dimensional concept. We introduce a multidimensional framework for characterizing the citation impact of a publication. In addition to the level of citation impact, quantified by the number of citations received by a publication, we also conceptualize and operationalize the depth and breadth and the dependence and independence of the citation impact of a publication. The pro…

  • Special issue on bibliographic data sources

    Open AccessLudo Waltman, Vincent LarivièreARTICLEQuantitative Science Studies2020

    Research in quantitative science studies relies on an increasingly broad range of data sources, providing data on scholarly publications, social media activity, peer review, research funding, the scholarly workforce, scientific prizes, and so on. However, there is one type of data source that remains at the heart of research in quantitative science studies: bibliographic databases. These data sources have increasingly diversified over the last de…

  • Opening science

    Open AccessLudo Waltman, Vincent Larivière et al.ARTICLEQuantitative Science Studies2020

    Journal of Informetrics (JOI) was created in 2006 to serve the dynamic, interdisciplinary, and rapidly growing field of informetrics (Egghe, 2005, 2006a, 2006b, 2015). Leo Egghe, the founding Editor-in-Chief of JOI, attributed this growth to the increasing attraction of “scientists from fields such as mathematics, physics and computer sciences, thereby considerably increasing the number of researchers engaged in informetrics” (Egghe, 2006b, p. 4)…

  • A principled methodology for comparing relatedness measures for clustering publications

    Open AccessLudo Waltman, Kevin W Boyack et al.ARTICLEQuantitative Science Studies2020

    There are many different relatedness measures, based for instance on citation relations or textual similarity, that can be used to cluster scientific publications. We propose a principled methodology for evaluating the accuracy of clustering solutions obtained using these relatedness measures. We formally show that the proposed methodology has an important consistency property. The empirical analyses that we present are based on publications in t…

  • From Louvain to Leiden

    Open AccessVincent Traag, Ludo Waltman et al.ARTICLEScientific Reports2019

    Community detection is often used to understand the structure of large and complex networks. One of the most popular algorithms for uncovering community structure is the so-called Louvain algorithm. We show that this algorithm has a major defect that largely went unnoticed until now: the Louvain algorithm may yield arbitrarily badly connected communities. In the worst case, communities may even be disconnected, especially when running the algorit…

  • Science of science

    Open AccessSanto Fortunato, Carl T Bergstrom et al.ARTICLEScience2018

    The whys and wherefores of SciSci The science of science (SciSci) is based on a transdisciplinary approach that uses large data sets to study the mechanisms underlying the doing of science—from the choice of a research problem to career trajectories and progress within a field. In a Review, Fortunato et al. explain that the underlying rationale is that with a deeper understanding of the precursors of impactful science, it will be possible to deve…

  • A review of the literature on citation impact indicators

    Open AccessLudo WaltmanARTICLEJournal of Informetrics2016

  • Large-scale analysis of the accuracy of the journal classification systems of Web of Science and Scopus

    Open AccessQi Wang, Ludo WaltmanARTICLEJournal of Informetrics2016

  • Constructing bibliometric networks

    Open AccessAntonio Perianes‐Rodríguez, Antonio Perianes-Rodriguez et al.ARTICLEJournal of Informetrics2016

  • Field-normalized citation impact indicators and the choice of an appropriate counting method

    Open AccessLudo Waltman, Nees Jan van EckARTICLEJournal of Informetrics2015

  • Bibliometrics

    Open AccessDiana Hicks, Paul Wouters et al.ARTICLENature2015

  • Visualizing Bibliometric Networks

    Open AccessNees Jan van Eck, Ludo WaltmanCHAPTERMeasuring Scholarly Impact2014

  • CitNetExplorer

    Open AccessNees Jan van Eck, Ludo WaltmanARTICLEJournal of Informetrics2014

  • A smart local moving algorithm for large-scale modularity-based community detection

    Open AccessLudo Waltman, Nees Jan van EckARTICLEThe European Physical Journal B2013