  For more than 40 years, the Institute for Scientific Information (ISI, now
part of Thomson Reuters) produced the only available bibliographic databases
from which bibliometricians could compile large-scale bibliometric indicators.
ISI's citation indexes, now regrouped under the Web of Science (WoS), were the
major sources of bibliometric data until 2004, when Scopus was launched by the
publisher Reed Elsevier. For those who perform bibliometric analyses and
comparisons of countries or institutions, the existence of these two major
databases raises the important question of the comparability and stability of
statistics obtained from different data sources. This paper uses macro-level
bibliometric indicators to compare results obtained from the WoS and Scopus. It
shows that the correlations between the measures obtained with both databases
for the number of papers and the number of citations received by countries, as
well as for their ranks, are extremely high (R2 > .99). There is also a very
high correlation when countries' papers are broken down by field. The paper
thus provides evidence that indicators of scientific production and citations
at the country level are stable and largely independent of the database.
