Redshift-space distortions in the PSCz galaxy catalogue

results from the cosmic microwave background (CMB), with a small degree of tilt, it disagrees with the amplitude of matter perturbations estimated from the abundance of clusters by a factor of 2, independent of cosmology. A preliminary model fitting analysis combining the CMB with either the PSCz or cluster abundances shows that the cosmological matter density parameter Vma 0:29 ^ 0:09, and the IRAS bias parameter ba 1:22 ^ 0:28. However, the cluster abundances suggest that Dm;0:1a 0:60 ^ 0:09 and nsa 0:96 ^ 0:03, while the PSCz requires Dm;0:1a 0:34 ^ 0:05 and nsa 0:81 ^ 0:05. Given the physics of galaxy formation is poorly constrained, we conclude that IRAS galaxies and mass are only partially correlated.