  The methods presented in this paper allow for a statistical analysis
revealing centers of excellence around the world using programs that are freely
available. Based on Web of Science data, field-specific excellence can be
identified in cities where highly-cited papers were published significantly.
Compared to the mapping approaches published hitherto, our approach is more
analytically oriented by allowing the assessment of an observed number of
excellent papers for a city (in the sample) against the expected number. Using
this test, the approach cannot only identify the top performers in output but
the "true jewels." These are cities locating authors who publish significantly
more top cited papers than can be expected. As the examples in this paper show
for physics, chemistry, and psychology, these cities do not necessarily have a
high output of excellent papers.
