  In this article, which is based on the first part of my PhD thesis, I review
the statistics of the open string sector in T^6/(Z_2xZ_2) orientifold
compactifications of the type IIA string. After an introduction to the
orientifold setup, I discuss the two different techniques that have been
developed to analyse the gauge sector statistics, using either a saddle point
approximation or a direct computer based method. The two approaches are
explained and compared by means of eight- and six-dimensional toy models. In
the four-dimensional case the results are presented in detail. Special emphasis
is put on models containing phenomenologically interesting gauge groups and
chiral matter, in particular those containing a standard model or SU(5) part.

High Energy Physics - Theory