EPFL Statistics Seminar

Dr. Finn Lindgren

Title: Quantifying the uncertainty of contour maps

Abstract

Contour maps are ubiquitous for visualising estimated spatial fields, but the uncertainty associated with such maps has been given a surprisingly small amount of attention. The question is closely connected with the dual problem of constructing credible regions for excursion sets, which leads to a more stringent formulation of the problem. With computational implementations, we can answer questions such as "How many or few contours levels is it reasonable to use, given the inherent uncertainty?". I will discuss these issues in particular in the context of Bayesian latent Gaussian random field models estimated with Integrated Nested Laplace Approximations.

Dr. David Kraus

Title: Regularized classification of functional data under incomplete observation

Abstract

Classification of functional data into two groups by linear classifiers is considered on the basis of one-dimensional projections of functions. Finding the best classifier is seen as an optimization problem that can be approximately solved by regularization methods, e.g., the conjugate gradient method with early stopping, the principal component method and the ridge method. We study the empirical version with finite training samples consisting of incomplete functions observed on different subsets of the domain and show that the optimal, possibly zero, misclassification probability can be achieved in the limit along a possibly non-convergent empirical regularization path. We propose a domain extension and selection procedure that finds the best domain beyond the common observation domain of all curves. In a simulation study we compare the different regularization methods and investigate the performance of domain selection. Our methodology is illustrated on a medical data set, where we observe a substantial improvement of classification accuracy due to domain extension.

The talk is based on joint work with Marco Stefanucci.

Dr. Phyllis Wan

Title: TBA

Abstract

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Dr. Guillaume Obozinski

Title: TBA

Abstract

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Prof. Rainer von Sachs

Title: TBA

Abstract

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