  Numerical simulations of variants of the CDM~model with different
cosmological parameters are used to compare statistical measures such as mass
spectra, merger processes, and autocorrelation functions, for different models
with relevant observations. The degree of virialisation of the halos is
checked, and also which properties distinguish recent mergers. Mergers occur
mostly in deep potential wells and mark the most important structure formation
processes. As consequence, the autocorrelation function of merged halos has a
higher amplitude and is steeper than that of the virialized clusters. This
effect can also be seen for ultraluminous IRAS galaxies which are thought to be
results from ongoing merging events.
