  We use weighted mean and median statistics techniques to combine individual
estimates of Omega_m0, the present mean mass density in non-relativistic
matter, and determine the observed values and ranges of Omega_m0 from different
combinations of data. The derived weighted mean Omega_m0 values are not good
representatives of the individual measurements, under the assumptions of
Gaussianity and negligible correlation between the individual measurements.
This could mean that some observational error bars are under-estimated.
Discarding the most discrepant about 5% of the measurements generally
alleviates but does not completely resolve this problem. While the results
derived from the different combinations of data are not identical, they are
mostly consistent, and a reasonable summary of the median statistics analyses
is 0.2 <= Omega_m0 <= 0.35 at two standard deviations.
