Since the real Universe is clumpy and inhomogeneous even at rather large scale such as 100 Mpc, we may wonder whether the isotropic and homogeneous Friedmann model is valid when we compare some cosmological parameters with the observed values. The observed Hubble parameter H0 or the density parameter Ω0 might be deviated from the theoretically expected ones from the Friedmann model. In fact, the density parameter Ω0 seems to vary depending on the observational methods and the distance scales. Furthermore, our Universe seems to possess a fractal property in the galaxy distributions at least at scale up to 10 Mpc.