  Comparing the gravitational acceleration induced on the Local Group of
galaxies by different tracers of the underline density field we estimate,
within the linear gravitational instability theory and the linear biasing
ansatz, their relative bias factors. Using optical SSRS2 galaxies, IRAS (PSCz)
galaxies and Abell/ACO clusters, we find b_{O,I} ~ 1.21 +- 0.06 and b_{C,I} ~
4.3 +- 0.8, in agreement with other recent studies. Finally, there is an
excellent one-to-one correspondence of the PSCz and Abell/ACO cluster dipole
profiles, once the latter is rescaled by b_{C,I}, out to at least ~150 h^{-1}
Mpc.
