Which cities' paper output and citation impact are above expectation in   information science? Some improvements of our previous mapping approaches
  Bornmann and Leydesdorff (in press) proposed methods based on Web-of-Science data to identify field-specific excellence in cities where highly-cited papers were published more frequently than can be expected. Top performers in output are cities in which authors are located who publish a number of highly-cited papers that is statistically significantly higher than can be expected for these cities. Using papers published between 1989 and 2009 in information science improvements to the methods of Bornmann and Leydesdorff (in press) are presented and an alternative mapping approach based on the indicator I3 is introduced here. The I3 indicator was introduced by Leydesdorff and Bornmann (in press). 
Lutz Bornmann and Loet Leydesdorff
cs.DL