[Statlist] Next talks: Friday, December 17, 2010

[Cecilia Rey]

ETH and University of Zurich

Proff. P. B�hlmann - L. Held - H.R. Kuensch - M. Maathuis - S. van de Geer

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We are glad to announce the following talks on
*
*

*Friday, December 17, 2010, *
*
- 14.15h *with *Mrs Caroline Uhler, University of California Berkeley and*


*- 15.15h *with *Mr Victor Panaretos, EPFL Lausanne*

*
**ETH Zurich HG G 19.1*
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1) Title and Abstract of *Caroline Uhler:

Geometry of maximum likelihood estimation in Gaussian graphical models

*We study maximum likelihood estimation in Gaussian graphical models 
from the perspective of convex algebraic geometry. It is well-known that 
the maximum likelihood estimator (MLE) exists with probability one if 
the number of observations is at least as large as the number of 
variables. We examine the situation with fewer samples for bipartite 
graphs and grids. Taking an algebraic approach we find the first example 
of a graph for which the MLE exists with probability one even when the 
number of observations equals the treewidth of the underlying graph.
*

*2)Title and Abstract of*Victor Panaretos:
*
*Second-Order Comparison of Random Functions and DNA Geometry*

Given two samples of continuous zero-mean iid Gaussian random functions 
on [0,1], we consider the problem of testing whether they share the same 
covariance operator. Our study is motivated by the problem of 
determining whether the mechanical properties of short strands of DNA 
are significantly affected by their base-pair sequence; though expected 
to be true, this effect had so far not been observed in 
three-dimensional electron microscopy data. The testing problem is seen 
to involve aspects of ill-posed inverse problems and a test based on a 
KarhunenLo�ve approximation of the HilbertSchmidt distance of the 
empirical covariance operators is proposed and investigated. When 
applied to a dataset of DNA minicircles obtained through the electron 
microscope, our test seems to suggest potential sequence effects on DNA 
shape.


Both abstracts are also to be found under the following link: 
http://stat.ethz.ch/events/research_seminar

--
ETH Z�rich
Seminar f�r Statistik
Cecilia Rey-Lutz, HG G10.3
R�mistrasse 101
CH-8092 Zurich
mail: rey using stat.math.ethz.ch
phone: +41 44 632 3438/fax: +41 44 632 1228


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