Leydesdorff, L On the normalization and visualization of author co-citation data: Salton's cosine versus the Jaccard index JOURNAL OF THE AMERICAN SOCIETY FOR INFORMATION SCIENCE AND TECHNOLOGY, 59 (1): 77-85 JAN 1 2008

[Eugene Garfield]

E-mail Address: loet at leydesdorff.net 

Author(s): Leydesdorff, L (Leydesdorff, Loet) 

Title: On the normalization and visualization of author co-citation data: 
Salton's cosine versus the Jaccard index 

Source: JOURNAL OF THE AMERICAN SOCIETY FOR INFORMATION SCIENCE AND 
TECHNOLOGY, 59 (1): 77-85 JAN 1 2008 

Language: English 

Document Type: Article 

Keywords Plus: SIMILARITY MEASURES; PEARSONS-R; COLLABORATION; SCIENCE
 
Abstract: The debate about which similarity measure one should use for the 
normalization in the case of Author Co-citation Analysis (ACA) is further 
complicated when one distinguishes between the symmetrical co-citation-or, 
more generally, co-occurrence-matrix and the underlying asymmetrical 
citation-occurrence-matrix. In the Web environment, the approach of 
retrieving original citation data is often not feasible. In that case, one 
should use the Jaccard index, but preferentially after adding the number 
of total citations (i.e., occurrences) on the main diagonal. Unlike 
Salton's cosine and the Pearson correlation, the Jaccard index abstracts 
from the shape of the distributions and focuses only on the intersection 
and the sum of the two sets. Since the correlations in the co-occurrence 
matrix may be spurious, this property of the Jaccard index can be 
considered as an advantage in this case. 

Addresses: Amsterdam Sch Commun Res, NL-1012 CX Amsterdam, Netherlands 

Reprint Address: Leydesdorff, L, Amsterdam Sch Commun Res, 
Kloveniersbrugwal 48, NL-1012 CX Amsterdam, Netherlands.
 
E-mail Address: loet at leydesdorff.net 

Cited Reference Count: 29 

Times Cited: 0 

Publisher: JOHN WILEY & SONS INC 

Publisher Address: 111 RIVER ST, HOBOKEN, NJ 07030 USA 

ISSN: 1532-2882 

29-char Source Abbrev.: J AM SOC INF SCI TECHNOL 

ISO Source Abbrev.: J. Am. Soc. Inf. Sci. Technol. 

Source Item Page Count: 9 

Subject Category: Computer Science, Information Systems; Information 
Science & Library Science 

ISI Document Delivery No.: 252CR 

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