A wide variety of numerical models of gravitational clustering are used to assess error in estimates of the mass density of the Universe from Virgo infall. The mean estimate of density is too low in both critical-density and low-density models, and it has a large dispersion in all models. Biased cold-dark-matter models produce an estimate of mass density in good agreement with observational estimates from infall.

• Received 28 March 1986

DOI:https://doi.org/10.1103/PhysRevLett.57.257