UNIVERSITY OF GLASGOW
STATISTICS SEMINAR PROGRAMME
Wednesday, 11th October, 3 pm
Fractal and aggregate tessellations
Sergei ZUYEV (University of Strathclyde)
Wednesday, 25th October 2000, 3 pm (Glasgow-Strathclyde Partnership Seminar)
Perfect simulation and stochastic geometry
Jesper M{\O}LLER (Aalborg University, Denmark)
Wednesday, 22nd November, 3 pm
Cost-effectiveness of new drugs
Tony O'HAGAN (University of Sheffield)
Wednesday, 6th December, 3 pm
Statistical aspects of BSE and nvCJD: implications for the public
health
Sheila BIRD (MRC Biostatistics Unit, Cambridge)
Seminars take place in Room 1f(203), Mathematics Building,
University of Glasgow
For further information please contact the seminar organiser:
Ilya Molchanov
University of Glasgow : e-mail: [log in to unmask]
Department of Statistics : Ph.: + 44 141 330 5141
Glasgow G12 8QW : Fax: + 44 141 330 4814
Scotland, U.K. : http://www.stats.gla.ac.uk/~ilya/
ABSTRACTS
FRACTAL AND AGGREGATE TESSELLATIONS
Voronoi tessellation is one of the simplest model for many systems
employing subdivisions of space. Quite often, however, more realistic
modelling calls for more complex tessellations that could take into
consideration the observed irregularity of cells. Let T_0, T_1,... be
a sequence of tessellations which cells are associated with
nuclei. For each T_0-cell C(x) with nucleus x the aggregate cell
C_0^1(x) of level 1 is the union of those cells of T_1 which nuclei
lie in C(x). The second level aggregate cell C_0^2(x) is the union of
those T_2-cells which nuclei lie in C_0^1(x), etc. Such aggregate
tessellations appear naturally, for instance, in modelling of
hierarchical telecommunications networks, where the the cells C_0^n
represent the service zones of switches (n+1)-levels above in the
hierarchical chain. Even if all T_i are Voronoi tessellations, the
aggregate tessellations' cells may be empty, they are not, in general,
convex nor connected nor contain their nuclei. We present results for
aggregate tessellations that are based on stationary random
tessellations, mainly Poisson-Voronoi ones. We find expressions for a
typical aggregate cell's coverage probability, give bounds on
variation of its boundary and study conditions assuring existence of
the limit fractal tessellation as n grows to infinity. The talk will
(hopefully) be assisted by a computer program PVAT downloadable from
the author's web-page, enabling construction and visualisation of
aggregate tessellations.
PERFECT SIMULATION AND STOCHASTIC GEOMETRY
Ordinary MCMC methods are only correct in the limit where an infinite
number of steps in the simulations have been performed. A recent
topic, which has drawn great attention after the seminal work of Propp
and Wilson (1996), is perfect simulation where one is assured that
equilibrium has been attained. Perfect simulation seems particular
useful for models used in stochastic geometry. In the talk I'll review
recent developments on perfect simulation and stochastic geometry
based on my own and others research.
COST-EFFECTIVENESS OF NEW DRUGS
Whereas regulation of new drugs has concentrated in the past on their
effectiveness, there is increasing interest in looking at
cost-effectiveness. In the UK, for instance, the National Institute
for Clinical Excellence has been created to advise the NHS on the
best and most cost-effective treatments and procedures.
This talk will outline some Bayesian methods for analysing both cost
and efficacy data from a clinical trial. I will focus on one example
where the importance of prior information is clear, and where I will
argue that conventional methods cannot handle 'outliers' in the cost
data properly.
STATISTICAL ASPECTS OF BSE AND NVCJD: IMPLICATIONS FOR THE PUBLIC
HEALTH
After a brief historical account which includes statistical
aspects of quality control at abattoirs, three current
statistical issues of public health importance are addressed:
1. maternal transmission, such as from BSE-dam to calf;
2. whether age-related consumption of bovine meat products is
sufficient to explain the younger age of nvCJD cases;
3. design considerations in estimating prevalence of
pre-clinical nvCJD.
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