  The new excellence indicator in the World Report of the SCImago Institutions
Rankings (SIR) makes it possible to test differences in the ranking in terms of
statistical significance. For example, at the 17th position of these rankings,
UCLA has an output of 37,994 papers with an excellence indicator of 28.9.
Stanford University follows at the 19th position with 37,885 papers and 29.1
excellence, and z = - 0.607. The difference between these two institution thus
is not statistically significant. We provide a calculator at
http://www.leydesdorff.net/scimago11/scimago11.xls in which one can fill out
this test for any two institutions and also for each institution on whether its
score is significantly above or below expectation (assuming that 10% of the
papers are for stochastic reasons in the top-10% set).
