  We propose a simple approach for studying systems of compressed matter based
on the Thomas-Fermi statistical model of single atom. The central point of our
work is the development of the concept of ``statistical ionization'' by
compression; in simple terms, we calculate the fraction of electrons within the
atom whose positive energy, due to the compression, exceeds the negative
binding energy electron-nucleus. Next we extend this concept from a single atom
to macroscopic systems and write the corresponding equation of state. Positive
aspects as well as limitations of the model are illustrated and discussed
through all the paper.
