Borrowing Strength with Nonexchangeable Priors over Subpopulations ATTENZIONE: il seminario avrà luogo presso AULA CONSIGLIO VII Piano Dipartimento Matematica Politecnico di MILANO

We introduce a nonparametric Bayesian model for a phase II clinical trial with patients presenting different subtypes of the disease under study. The objective is to estimate the success probability of an experimental therapy for
each subtype. We consider the case when small sample sizes require extensive borrowing of information across subtypes,but the subtypes are not a priori exchangeable. We introduce a variation of the product partition model that allows us to model a nonexchangeable prior structure.