  We undertake a critical evaluation of recent observational information on
$\Omega_m$ and $\Omega_\Lambda$ in order to identify possible sources of
systematic errors and effects of simplified statistical analyses. We combine
observations for which the results have been published in the form of
likelihood contours in the $\Omega_m ,\Omega_\Lambda$ plane. We approximate the
contours by fifth order polynomials, and we then use the maximum likelihood
method to obtain joint likelihood contours for the combined data. In the choice
of statistical merits we aim at minimum loss of information rather than at
minimum variance. We find that $\Omega_0 = \Omega_m + \Omega_\Lambda = 0.99\pm
0.04 \pm 0.03$, where the first error is mainly statistical and the second
error is systematical. In a flat Universe we find $\Omega_m^{flat} = 0.31 \pm
0.04 \pm 0.04$.
