Theoretical expectation vs. numerical simulation of the statistical distribution of v_z ∕v, where v_z is the radial velocity difference between galaxies in randomly oriented pairs and v the true velocity difference. The number of simulated pairs is here N ≈ 10 000. Apart from statistical fluctuations, the obtained probability distribution of the radial velocity is constant in the range [0, v], in agreement with the theoretical expectation (given by the constant red line).