DEPARTMENT OF STATISTICS Statistics Colloquium University of Connecticut Storrs, Connecticut The Department of Statistics Cordially invites you to a Colloquium Yajuan Si Assistant Professor Department of Population Health Sciences Department of Biostatistics & Medical Informatics School of Medicine and Public Health University of Wisconsin-Madison Bayesian Latent Pattern Mixture Models for Handling Attrition in Panel Studies with Refreshment Samples ABSTRACT Many panel students collect refreshment samples---new, randomly sampled respondents who complete the questionnaire at the same time as a subsequent wave of the panel. With appropriate modeling, these samples can be leveraged to correct inferences for biases caused by non-ignorable attrition. We present such a model when the panel includes many categorical survey variables. The model relies on a Bayesian latent pattern mixture model, in which an indicator for attrition and the survey variables are modeled jointly via a latent class model. We allow the multinomial probabilities within classes to depend on the attrition indicator, which offers additional flexibility over standard applications of latent class models. We present results of simulation studies that illustrate the benefits of this flexibility. We apply the model to correct attrition bias in an analysis of data from the 2007-2008 Associated Press/Yahoo News election panel study. This is joint work with Jerry Reiter and Sunshine Hillygus at Duke University. DATE: Wednesday, April 1, 2015 TIME: 4:00 p.m. PLACE: AUST 105 Coffee at 3:30 in AUST 326