Predicted number n(z) of DLA systems per unit redshift for various cosmological models vs. observational data. The solid error crosses (1 σ) are reproduced from Storrie‐Lombardi et al. (1996), with the vertical dashed error bars indicating 2 σ error. The dotted error crosses (1 σ) are taken from Wolfe et al. (1995). The heavy curves connecting z = 2, 3, and 4 are values calculated for each model. The model names correspond to the names in Table 1, where their parameters are listed.