  The integrated properties of young star clusters are subject to large
cluster-to-cluster variations because they depend directly on small numbers of
bright stars. At ages at which red supergiants are expected to exist, these
luminous but rare stars can be blamed for most of the variations. If unresolved
clusters are to be used to constrain red supergiant models, methods must be
developed that take these stochastic fluctuations into account. We discuss
prospects and open issues in this field, based on recent work on high mass
clusters in M82, and on first experiments towards a Bayesian study of cluster
populations.
