Cosmological Bayesian model selection

Bayesian model comparison can be used to decide whether the introduction of a new parameter is warranted by data. I focus on the Savage-Dickey density ratio as a method to compute the Bayes factor of nested models without carrying out a computationally demanding multi-dimensional integration. I present a new procedure (called "PPOD") to forecast the Bayes factor of a future observation. As an illustration, I consider a few central quantities in the current cosmological concordance model. Copyright © 2006 by Imperial College Press.