  Here we extract the geographical addresses of authors in the Citeseer
database of computer science papers. We show that the productivity of research
centres in the United States follows a power-law regime, apart from the most
productive centres for which we do not have enough data to reach definite
conclusions. To investigate the spatial distribution of computer science
research centres in the United States, we compute the two-point correlation
function of the spatial point process and show that the observed power-laws do
not disappear even when we change the physical representation from geographical
space to cartogram space. Our work suggests that the effect of physical
location poses a challenge to ongoing efforts to develop realistic models of
scientific productivity. We propose that the introduction of a fine scale
geography may lead to more sophisticated indicators of scientific output.
