  We discuss the large scale properties of standard cold dark matter
cosmological models characterizing the main features of the power-spectrum, of
the two-point correlation function and of the mass variance. Both the
real-space statistics have a very well defined behavior on large enough scales,
where their amplitudes become smaller than unity. The correlation function, in
the range 0<\xi(r)<1, is characterized by a typical length-scale r_c, at which
\xi(r_c)=0, which is fixed by the physics of the early universe: beyond this
scale it becomes negative, going to zero with a tail proportional to -(r^{-4}).
These anti-correlations represent thus an important observational challenge to
verify models in real space. The same length scale r_c characterizes the
behavior of the mass variance which decays, for r>r_c, as r^{-4}, the fastest
decay for any mass distribution. The length-scale r_c defines the maximum
extension of (positively correlated) structures in these models. These are the
features expected for the dark matter field: galaxies, which represent a biased
field, however may have differences with respect to these behaviors, which we
analyze. We then discuss the detectability of these real space features by
considering several estimators of the two-point correlation function. By making
tests on numerical simulations we emphasize the important role of finite size
effects which should always be controlled for careful measurements.
