  Using Web-of-Science data, portfolio analysis in terms of journal coverage
can be projected on a base map for units of analysis such as countries, cities,
universities, and firms. The units of analysis under study can be compared
statistically across the 10,000+ journals. The interdisciplinarity of the
portfolios is measured using Rao-Stirling diversity or Zhang et al.'s (in
press) improved measure 2D3. At the country level we find regional
differentiation (e.g., Latin-American or Asian countries), but also a major
divide between advanced and less-developed countries. Israel and Israeli cities
outperform other nations and cities in terms of diversity. Universities appear
to be specifically related to firms when a number of these units are
exploratively compared. The instrument is relatively simple and
straightforward, and one can generalize the application to any document set
retrieved from WoS. Further instruction is provided online at
http://www.leydesdorff.net/portfolio .
