Correlation function from 1000 subcubes of the Millennium Simulation, computed using the LS estimator. The points and error bars show the correlation function ξ_n ≡ ξ(n·Δs) for Δs = 5 h^-1Mpc (see text for details) averaged over the 1000 subcubes of side length 50 h^-1Mpc, as well as the standard deviation. For the blue circles, the random catalog for each subcube contains 100 halos, as opposed to 10 000 halos for the red crosses.