  The standard Bayesian model formalism comparison cannot be applied to most
cosmological models as they lack well-motivated parameter priors. However, if
the data-set being used is separable then it is possible to use some of the
data to obtain the necessary parameter distributions, the rest of the data
being retained for model comparison. While such methods are not fully
prescriptive, they provide a route to applying Bayesian model comparison in
cosmological situations where it could not otherwise be used.
