Upcoming Colloquia

All seminars will be held in the MBI Lecture Hall - Jennings Hall, Room 355 - unless otherwise noted.

September 21, 2015 3:00 - 3:50PM
Host: Greg Rempala

We develop a model-based empirical Bayes approach to variable selection problems where the number of predictors is very large, possibly much larger than the number of responses (the so-called “large p, small n” problem). Motivated by QTL (quantitative trait loci) studies, we consider the multiple linear regression setting, where the response is assumed to be a continuous variable, and it is a linear function of the predictors. The explanatory variables in the linear model can have a positive effect on the response, a negative effect, or no effect. Thus, we model the effects of the linear predictors as a three-component mixture, where each component follows a normal distribution with mean μ, −μ, or 0. A key assumption in our approach is that only a small fraction of the candidate predictors have a non-zero effect on the response variable. By treating the putative variables as random effects we get shrinkage estimation, which results in increased power. This approach is computationally efficient because the number of parameters that have to be estimated is small, and remains constant regardless of the number of explanatory variables in the linear regression model. The model parameters are estimated using the EM algorithm which leads to significantly faster convergence, compared with simulation-based methods. Furthermore, we employ computational tricks which allow us to increase the speed of our algorithm, to handle a very large number of putative variables, and to avoid multicollinearity in the regression model.

TBD
October 19, 2015 3:00 - 3:50PM
Host: Ching-Shan Chou

Abstract not submitted.

TBD
November 02, 2015 3:00 - 3:50PM
Host: Adriana Dawes

Abstract not submitted.

TBD
November 09, 2015 3:00 - 3:50PM
Host: TBD

Abstract not submitted.

TBD
March 07, 2016 3:00 - 3:50PM
Host: Greg Rempala

No abstract has been provided.

TBD
March 28, 2016 3:00 - 3:50PM
Host: Marty Golubitsky

Abstract not submitted.

TBD
April 04, 2016 3:00 - 3:50PM

No abstract has been provided.