  System modeling is a classical approach to ensure their reliability since it
is suitable both for a formal verification and for software testing techniques.
In the context of model-based testing an approach combining random testing and
coverage based testing has been recently introduced [9]. However, this approach
is not tractable on quite large models. In this paper we show how to use
statistical approximations to make the approach work on larger models.
Experimental results, on models of communicating protocols, are provided; they
are very promising, both for the computation time and for the quality of the
generated test suites.
