Journal maps on the basis of Scopus data: a comparison with the Journal Citation Reports of the ISI

Using the Scopus dataset (1996-2007) a grand matrix
of aggregated journal-journal citations was constructed.
This matrix can be compared in terms of the network
structures with the matrix contained in the Journal
Citation Reports (JCR) of the Institute of Scientific Information
(ISI). Because the Scopus database contains a
larger number of journals and covers the humanities,
one would expect richer maps. However, the matrix is in
this case sparser than in the case of the ISI data. This
is because of (a) the larger number of journals covered
by Scopus and (b) the historical record of citations older
than 10 years contained in the ISI database. When the
data is highly structured, as in the case of large journals,
the maps are comparable, although one may have to vary
a threshold (because of the differences in densities). In
the case of interdisciplinary journals and journals in the
social sciences and humanities, the new database does
not add a lot to what is possible with the ISI databases