**************************************************************** STATISTICS SEMINARS @ COLLEGIO CARLO ALBERTO ****************************************************************
Venerdi' 4 Luglio 2014 alle ore 12:00, presso la sala rossa del Collegio Carlo Alberto, Moncalieri (TO), si terra' il seguente seminario:
Michael J. DANIELS (University of Texas at Austin) A FLEXIBLE BAYESIAN APPROACH TO MONOTONE MISSING DATA IN LONGITUDINAL STUDIES WITH INFORMATIVE MISSINGNESS WITH APPLICATION TO AN ACUTE SCHIZOPHRENIA CLINICAL TRIAL
Abstract: We develop a Bayesian nonparametric model for a longitudinal response in the presence of nonignorable missing data. Our general approach is to first specify a {\em working model} that flexibly models the missingness and full outcome processes jointly. We specify a Dirichlet process mixture of missing at random (MAR) models as a prior on the joint distribution of the working model. This aspect of the model governs the fit of the observed data by modeling the observed data distribution as the marginalization over the missing data in the working model. We then separately specify the conditional distribution of the missing data given the observed data and dropout. This approach allows us to identify the distribution of the missing data using identifying restrictions as a starting point. We propose a framework for introducing sensitivity parameters, allowing us to vary the untestable assumptions about the missing data mechanism smoothly. Informative priors on the space of missing data assumptions can be specified to combine inferences under many different assumptions into a final inference and accurately characterize uncertainty. These methods are motivated by, and applied to, data from a clinical trial assessing the efficacy of a new treatment for acute Schizophrenia.
Joint work with Antonio Linero at the University of Florida
Tutti gli interessati sono invitati a partecipare.
Il seminario e' organizzato dalla "de Castro" Statistics Initiative (http://www.carloalberto.org/stats) in collaborazione con il Collegio Carlo Alberto.
Cordiali saluti, Matteo Ruggiero
--- Matteo Ruggiero University of Torino & Collegio Carlo Alberto http://web.econ.unito.it/ruggiero