  We use the StarTrack stellar population synthesis code to analyze properties
of double compact object binaries as sources of gravitational waves. Since the
distribution of lifetimes of these objects extends up to the Hubble time we
conclude that a proper calculation of the expected rate must include a full
cosmological model. We present such model, calculate the expected coalescence
rates, and analyze the intrinsic sensitivity of these rates to the model
assumptions. We find that the rate alone is a very poor estimator of the
underlying stellar evolution model. However we show that the distribution of
observed chirp masses is very sensitive to the underlying stellar evolution
model, while it is very insensitive to the underlying cosmology, star formation
rate history and variation of detector sensitivity.
