In their letter to PNAS and a comprehensive set of notes on arXiv
[arXiv:0909.5673v2], Christian Robert, Kerrie Mengersen and Carla Chen (RMC)
represent our approach to model criticism in situations when the likelihood
cannot be computed as a way to "contrast several models with each other". In
addition, RMC argue that model assessment with Approximate Bayesian Computation
under model uncertainty (ABCmu) is unduly challenging and question its Bayesian
foundations. We disagree, and clarify that ABCmu is a probabilistically sound
and powerful too for criticizing a model against aspects of the observed data,
and discuss further the utility of ABCmu.Comment: Reply to [arXiv:0909.5673v2
