REMINDER: THIRD JOINT WARWICK-OXFORD STATISTICS SEMINAR
The third joint Warwick-Oxford Statistics seminar will take place
Thursday 23 October 2008 (this week Thursday).
The programme is as follows.
2:30 Julian Besag (University of Bath, and University of Washington, Seattle):
Continuum limits of Gaussian Markov random fields: resolving the conflict with
geostatistics
Abstract: For more than 30 years, Markov random fields (equivalently,
graphical models with undirected edges) have been used with some success to
account for spatial variation in data. Applications include agricultural crop
trials, geographical epidemiology, medical imaging, remote sensing, astronomy,
and microarrays. Almost all of the examples involve (hidden) Gaussian MRF
formulations.
MRFs refer to fixed regular or irregular discrete lattices or arrays and questions
arise regarding inconsistencies between MRFs specified at differing scales,
especially for regional data. Ideally, one would often prefer an underlying
continuum formulation, as in geostatistics, which can then be integrated to
the regions of interest. However, limiting continuum versions of MRFs, as
lattice spacing decreases, proved elusive until recently.
This talk briefly presents some motivating examples and shows that limiting
processes indeed exist but are defined on arbitrary regions of the plane rather
than pointwise. Especially common is the conformally invariant de Wijs
process, which coincidentally was used originally by mining engineers but
which became unfashionable as geostatistics developed. Convergence is
generally very fast. The de Wijs process is also shown to be a natural
extension of Brownian motion to the plane. Other processes, including the thin-
plate spline, can be derived as limits of MRFs. The talk closes by briefly
discussing data analysis.
3:30 - 4:00 Tea break
4:00 Susan Lewis (University of Southampton): Screening experiments
Abstract: Discovery and development in science and industry often involves
investigation of many features or factors that could potentially affect the
performance of a product or process. In factor screening, designed
experiments are used to identify efficiently the few features that influence key
properties of the system under study. A brief overview of this broad area will
be presented. This will be followed by discussion of a variety of methods with
particular emphasis on industrial screening. Ideas will be motivated and
illustrated through examples, including a case study from the automotive
industry.
5:00 Reception.
The event takes place at the
Mary Ogilvie Lecture Theatre, St Anne's College, Woodstock Road, Oxford.
For directions see http://www.stannes.ox.ac.uk/about/how_to_find_us.html.
All welcome!
Gesine Reinert
David Cox
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