  We compare different approximations for the wait time in distribution
networks, in which all warehouses use an (R,Q)-order policy. Reporting on the
results of extensive computational experiments, we evaluate the quality of
several approximations presented in the literature. In these experiments, we
used a simulation framework that was set-up to replicate the behavior of the
material flow in a real distribution network rather than to comply with the
assumptions made in the literature for the different approximation. First, we
used random demand data to analyze which approximation works best under which
conditions. In a second step, we then checked if the results obtained for
random data can be confirmed also for real-world demand data from our
industrial partner. Eventually, we derive some guidelines which shall help
practitioners to select approximations which are suited well for their
application. Still, our results recommend further testing with the actual
application's data to verify if a chosen wait time approximation is indeed
appropriate in a specific application setting.
