The Dyer-Roeder distance-redshift relation in inhomogeneous universes

Using Monte-Carlo methods, we determine the best-fit value of the homogeneity parameter alpha in the Dyer-Roeder distance-redshift relation for a variety of redshifts, inhomogeneity models and cosmological parameter values. The relation between alpha and the fraction of compact objects, f_p, is found to be approximately linear. This relation can be parametrized with reasonable accuracy for all cases treated in this paper by alpha = a*f_p, where a = 0.6.