MSc L. (Ludo) Waltman
Person photo
Organisation: Centre for Science and Technology Studies
Phone: +31-(0)71-5275806
Fax: +31-(0)71-5273911
E-Mail: waltmanlr@cwts.leidenuniv.nl
Webpage: http://www.ludowaltman.nl
Description:
Researcher. MSc in Economics & Informatics from Erasmus University Rotterdam (2005). Currently working on a PhD thesis in economics at Erasmus University Rotterdam. Working at CWTS from June 2009. Involved in various science mapping projects. Main research interests are science mapping and bibliometric indicators.
  
Publications (24)
Activities (2)
Research programs (2)
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A Comparison of Two Techniques for Bibliometric Mapping: Multidimensional Scaling and VOS
JOURNAL OF THE AMERICAN SOCIETY FOR INFORMATION SCIENCE AND TECHNOLOGY; 2010: 2405 - 2416
VOS is a new mapping technique that can serve as an alternative to the well-known technique of multidimensional scaling (MDS). We present an extensive comparison between the use of MDS and the use of VOS for constructing bibliometric maps. In our theoretical analysis, we show the mathematical ...
A recursive field-normalized bibliometric performance indicator: an application to the field of library and information science
SCIENTOMETRICS; 2011: 301 - 314
Two commonly used ideas in the development of citation-based research performance indicators are the idea of normalizing citation counts based on a field classification scheme and the idea of recursive citation weighing (like in PageRank-inspired indicators). We combine these two ideas in a single ...
A simple alternative to the h-index
ISSI Newsletter; 2009: 46 - 48
A unified approach to mapping and clustering of bibliometric networks
JOURNAL OF INFORMETRICS; 2010: 629 - 635
In the analysis of bibliometric networks, researchers often use mapping and clustering techniques in a combined fashion. Typically, however, mapping and clustering techniques that are used together rely on very different ideas and assumptions. We propose a unified approach to mapping and clustering ...
Appropriate similarity measures for author co-citation analysis
JOURNAL OF THE AMERICAN SOCIETY FOR INFORMATION SCIENCE AND TECHNOLOGY; 2008: 1653 - 1661
We provide in this article a number of new insights into the methodological discussion about author co-citation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors' co-citation profiles is not very satisfactory. We then discuss what kind of ...
Automatic term identification for bibliometric mapping
SCIENTOMETRICS; 2010: 581 - 596
A term map is a map that visualizes the structure of a scientific field by showing the relations between important terms in the field. The terms shown in a term map are usually selected manually with the help of domain experts. Manual term selection has the disadvantages of being subjective and ...
Bibliometric mapping of the computational intelligence field
INTERNATIONAL JOURNAL OF UNCERTAINTY FUZZINESS AND KNOWLEDGE-BASED SYSTEMS; 2007: 625 - 645
In this paper, a bibliometric study of the computational intelligence field is presented. Bibliometric maps showing the associations between the main concepts in the field are provided for the periods 1996-2000 and 2001-2005. Both the current structure of the field and the evolution of the field ...
Collaborations span 1,553 kilometres
NATURE; 2011: 154 - 154
Generalizing the h- and g- indices
JOURNAL OF INFORMETRICS; 2008: 263 - 271
We introduce two new measures of the performance of a scientist. One measure, referred to as the h(alpha)-index, generalizes the well-known h-index or Hirsch index. The other measure, referred to as the g(alpha)-index, generalizes the closely related g-index. We analyze theoretically the ...
How to Normalize Cooccurrence Data? An Analysis of Some Well-Known Similarity Measures
JOURNAL OF THE AMERICAN SOCIETY FOR INFORMATION SCIENCE AND TECHNOLOGY; 2009: 1635 - 1651
In scientometric research, the use of cooccurrence data is very common. In many cases, a similarity measure is employed to normalize the data. However, there is no consensus among researchers on which similarity measure is most appropriate for normalization purposes. In this article, we ...