Comparisons of those statistics measured in redshift space with the truth for 100 mock realizations of the ORS sample drawn from a hydrodynamic simulation of galaxies in a standard CDM universe. Upper left panel: Comparison between Δv_p, the true peculiar velocity difference of pairs of galaxies with projected separation less than 1 h⁻¹ Mpc, with their redshift‐space difference, π. Upper right panel: Difference π − Δv_p as a function of local density, as determined from a 400 km s⁻¹ Gaussian smoothing. Lower left panel: Comparison between the scale length α of the redshift‐space difference of pairs of galaxies with the standard deviation σ of their true peculiar velocity difference. For each realization, results are shown at a variety of local densities. Lower right panel: Fractional difference between these two quantities as a function of local density. A small scatter has been added to the ordinate in this plot to make it easier to read. The running mean is given by the thin solid line.