preprint version now available

Loet Leydesdorff loet at LEYDESDORFF.NET
Sat Nov 20 05:51:56 EST 2004

** apologies for cross-postings

Can the Sciences  <> be
Classified in terms of Aggregated Journal-Journal Citation Relations

using the  <> Journal Citation

 <> <pdf>

The aggregated citation relations among journals included in the Science
Citation Index provide us with a huge matrix which can be analyzed in
various ways. Using principal component analysis or factor analysis, the
factor scores can be used as indicators of the position of the cited
journals in the citing dimensions of the database. Unrotated factor scores
are exact, and the extraction of principal components can be made stepwise
since the principal components are independent. Rotation is necessary for
the designation, but a model is then necessarily assumed. This assumption
can be legitimated on pragmatic or theoretical grounds, but the resulting
outcomes remain sensitive to the assumptions in the model. This is
elaborated for the case of 'biochemistry'. The analytic solutions allow us
to test classifications in terms of the quality of the representation
against the structures contained in the database.


Loet Leydesdorff
Amsterdam School of Communications Research (ASCoR)
Kloveniersburgwal 48, 1012 CX Amsterdam
Tel.: +31-20- 525 6598; fax: +31-20- 525 3681
 <mailto:loet at> loet at ;

 <> The Challenge of
Scientometrics ;  <> The
Self-Organization of the Knowledge-Based Society

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