  The preparation procedure, an undefined notion in quantum theory, has not had
the relevance that it deserves in the interpretation of quantum mechanical
formalism. Here we utilize the concepts of identical and similar preparation
procedures to show the conceptual differences and mutual interconnections
between the statistical and the conventional interpretation of quantum
formalism. Although the statistical understanding, and its final logical
consequence, hidden variables theories (this connexion being explained in the
text), have a great intuitive appeal due to its fewer ontological difficulties,
both recent experimental results and some theoretical developments seem to
support an epistemic alternative closer to the conventional one. Nevertheless,
we must not rule out the possibility that new theorems or new explanatory
principles may modify the reigning supremacy of this interpretation.
