  Observations of large scale structure (LSS) and the Cosmic Microwave
Background (CMB) each place separate constraints on the values of cosmological
parameters. We calculate a joint likelihood based on various CMB experiments
and the IRAS 1.2Jy galaxy redshift survey and use this to find an overall
optimum with respect to the free parameters. Our formulation self-consistently
takes account of the underlying mass distribution, which affects both the CMB
potential fluctuations and the IRAS redshift distortion. This not only allows
more accurate parameter estimation, but also removes the parameter degeneracy
which handicaps calculations based on either approach alone. The family of Cold
Dark Matter (CDM) models analysed corresponds to a spatially-flat universe with
an initially scale-invariant spectrum and a cosmological constant. Free
parameters in the joint model are the mass density due to all matter (Omega_m),
Hubble's parameter (h = H_0 / 100km/s Mpc^-1), the quadrupole normalisation of
the CMB power spectrum (Q) in uK, and the IRAS light-to-mass bias (b_i).
Throughout the analysis, the baryonic density (Omega_b) is required is to
satisfy the nucleosynthesis constraint Omega_b h^2 = 0.024. Results from the
two data sets show good agreement, and the joint optimum lies at Omega_m=0.39,
h=0.53, Q=16.96uK, and b_i=1.21. The 68 per cent confidence intervals are:
0.29<Omega_m<0.53, 0.39<h<0.58, 15.34<Q<17.60, and 0.98<b_i<1.56. For the above
parameters the normalisation and shape of the mass power-spectrum are
sigma_8=0.67 and Gamma=0.15, and the age of the Universe is 16.5Gyr.
