  The Cosmological Principle states that the Universe is statistically
isotropic and homogeneous on large scales. In particular, this implies
statistical isotropy in the galaxy distribution, after removal of a dipole
anisotropy due to the observer's motion. We test this hypothesis with number
count maps from the NVSS radio catalogue. We use a local variance estimator
based on patches of different angular radii across the sky and compare the
source count variance between and within these patches. In order to assess the
statistical significance of our results, we simulate radio maps with the NVSS
specifications and mask. We conclude that the NVSS data is consistent with
statistical isotropy.
