Exploring the depth of dependency on particular industrial clusters would be a better measure of where diversification is most lacking.

ECONOMIST: One-firm economies: The Nokia effect | The

Michael Porter (see article), a professor at Harvard Business School, has looked recently at this seemingly paradoxical revival of industrial clusters.

ECONOMIST: Idea: Clustering | The

Industrial clusters have formed in health, transport and green technology.

ECONOMIST: To stay sexy, must the German capital remain poor?

The country recruited Brazilians and Peruvians of Japanese descent to work in the industrial clusters around Tokyo and Nagoya in Aichi prefecture that serve the country's giant carmakers and electronics firms.

ECONOMIST: Japanese immigration

In some cases, the ancillary services that grew up to service industrial clusters have remained in position and developed into vibrant new industries long after their original client industry has faded.

ECONOMIST: Idea: Clustering | The

Whereas in previous decades these traits gave clusters advantages over the big industrial sprawl of competing western economies, these days the processes are too inefficient to be competitive in all but the highest-value segments.

ECONOMIST: Italian textiles and China