  We compare the impacts of uncertainties in both binary population synthesis
models and the cosmic star formation history on the predicted rates of
Gravitational Wave compact binary merger (GW) events. These uncertainties cause
the predicted rates of GW events to vary by up to an order of magnitude.
Varying the volume-averaged star formation rate density history of the Universe
causes the weakest change to our predictions, while varying the metallicity
evolution has the strongest effect. Double neutron-star merger rates are more
sensitive to assumed neutron-star kick velocity than the cosmic star formation
history. Varying certain parameters affects merger rates in different ways
depending on the mass of the merging compact objects; thus some of the
degeneracy may be broken by looking at all the event rates rather than
restricting ourselves to one class of mergers.
