The paper by Ravi K. Sheth and Giuseppe Tormen explores the relationship between the abundance of dark matter haloes and their spatial distribution on large scales. They use a simple model to show that knowledge of the unconditional mass function alone is sufficient to accurately estimate the large-scale bias factor. The authors then apply this model to the mass functions measured in numerical simulations of different cosmological models (SCDM, OCDM, and ΛCDM) to compute the bias. The results indicate that this method is accurate for both less massive and more massive haloes. Specifically, they find that haloes that are less or more massive than typical $M_*$ haloes at the time of their formation are more or less clustered, respectively, compared to what the standard Press–Schechter mass function predicts. The paper also discusses the implications of these findings for galaxy formation models and the reionization history of the universe.The paper by Ravi K. Sheth and Giuseppe Tormen explores the relationship between the abundance of dark matter haloes and their spatial distribution on large scales. They use a simple model to show that knowledge of the unconditional mass function alone is sufficient to accurately estimate the large-scale bias factor. The authors then apply this model to the mass functions measured in numerical simulations of different cosmological models (SCDM, OCDM, and ΛCDM) to compute the bias. The results indicate that this method is accurate for both less massive and more massive haloes. Specifically, they find that haloes that are less or more massive than typical $M_*$ haloes at the time of their formation are more or less clustered, respectively, compared to what the standard Press–Schechter mass function predicts. The paper also discusses the implications of these findings for galaxy formation models and the reionization history of the universe.