We analyze subsamples of Abell and ACO cluster catalogs, in order to s
tudy the spatial properties of the large-scale matter distribution. Th
e subsamples analyzed are estimated to be nearly complete and are the
standard ones used in the correlation analysis by various authors. The
statistical analysis of cluster correlations is performed without any
assumptions on the nature of the distribution itself. The cluster sam
ples show fractal correlations up to sample limits (approximate to 70
h(-1) Mpc) with fractal dimension D approximate to 2, without any tend
ency towards homogenization. Our analysis shows that the standard corr
elation methods are incorrect, since they give a finite correlation le
ngth for a distribution that does not possess one. In particular, the
so-called correlation length r(0) is shown to be simply a fraction of
the sample size. Moreover we conclude that galaxies and clusters are t
wo different representations of the same self-similar structure and th
at the correlations of clusters are the continuation of those of galax
ies to larger scales.