MSc L. (Ludo) Waltman
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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 (14)
Activities (2)
Research programs (2)
12>>
A simple alternative to the h-index
ISSI Newsletter; 2009: 46 - 48
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 ...
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 ...
On the proper understanding of the limiting behavior of generalizations of the h- and g-indices
JOURNAL OF INFORMETRICS; 2009: 369 - 370
Q-learning agents in a Cournot oligopoly model
JOURNAL OF ECONOMIC DYNAMICS & CONTROL; 2008: 3275 - 3293
Q-learning is a reinforcement learning model from the field of artificial intelligence. We study the use of Q-learning for modeling the learning behavior of firms in repeated Cournot oligopoly games. Based on computer simulations, we show that Q-learning firms generally learn to collude with each ...
Robust Evolutionary Algorithm Design for Socio-Economic Simulation: Some Comments
COMPUTATIONAL ECONOMICS; 2009: 103 - 105
Some comments on Egghe's derivation of the impact factor distribution
JOURNAL OF INFORMETRICS; 2009: 363 - 366
In a recent paper, Egghe [Egghe, L. (in press). Mathematical derivation of the impact factor distribution. Journal of Informetrics] presents a mathematical analysis of the rank-order distribution of journal impact factors. The analysis is based on the central limit theorem. We criticize the ...