Correlation coefficient ρ between the measurements of the halo-matter power spectrum, P_hm(k), in different simulations for k ≤ 0.05 h Mpc⁻¹ as a function of halo mass bin and redshift. The red histograms show the distribution of the correlation coefficient between a simulation and its paired realization, while blue histograms are for the correlation coefficient between simulations with uncorrelated white-noise realizations.