We love maps on Berkeleyside, particularly when they demonstrate something that we knew in our hearts even without the data. (We also like maps that show us our preconceptions were wildly wrong. We just like maps.) So it was exciting to come across the recent research of Lutz Bornmann of Munich and Loet Leydesdorff of Amsterdam.
Bornmann and Leydesdorff undertook a study in spatial bibliometrics to determine which cities around the world have more scientific excellence than expected (you can read the entire draft paper here). Using data from Thomson Reuters’ Web of Science, Bornmann and Leydesdorff compared how many research papers cities produce in three fields — physics, chemistry and psychology — and then looked at how many of those papers were in the top 10% of citations in the fields.
If excellence were evenly distributed, the expectation would be that all research centers would have 10% of their papers in the top category. But of course the distribution is not even. Bornmann and Leydesdorff ran the data based on papers published in 2008 and then mapped the results — which produces the pretty — and pretty revealing — map above. Green circles show cities that did better than expected, with the radius showing the deviation from the expected number. Red circles show cities that did worse than expected.
How did Berkeley do? With the university and Berkeley Lab, clearly lots of scientific papers originate here. But do we get more than our fair share of excellence?
In physics, only Cambridge, Massachusetts does better than Berkeley in the United States. Globally, London was a touch ahead of Berkeley, but to a statistically insignificant degree. The researchers calculated that Berkeley should have produced 11.8 top 10% papers in physics, but in fact produced 39. Stanford also shows up as a nice green circle, but much smaller than Berkeley, with 16 top 10% papers compared to an expected 6.2.
In chemistry as well, Berkeley is also clearly in the top couple of centers worldwide. Its ratio of top 10% papers over the expected number (34 versus 6.3) is stronger than Cambridge, but Cambridge had more top 10% papers (39 against 8.3 expected). Stanford isn’t really in the race, with 10 top 10% papers against an expected 2.8.
It’s only in psychology that Berkeley falls into the ranks of the merely excellent cities. There’s still a green circle, but the difference between top 10% papers and expected is slim: 16 to 10.4. Stanford does better — 32 to 13.3 — but the U.S. hotspots are Los Angeles (79 top 10% against 37.9 expected) and New York City (112 top 10% against 65.5 expected). London is the clear global leader with 140 top 10% papers against 68.9 expected.
If you look at the maps from a global perspective two things pop out. First, the preponderance of green circles in North America and western Europe. Second, the huge red circles in physics and chemistry in Russia and the significant scattering of red circles in China and India. Let’s hope that Bornmann and Leydesdorff do a time series with the data in future so we can see if there is a shift in disproportionate excellence geographically.