The UNIVERSITY OF EDINBURGH
SCHOOL OF MATHEMATICS
Date: Friday 30 March 2012 at 3pm
Location: 6301 JCMB
Colin Aitken (The University of Edinburgh)
* The evaluation of evidence in forensic science for discrete data *
In forensic science the value of evidence is determined with the
likelihood ratio. This compares the likelihood of the evidence if the
prosecution proposition is true with the likelihood of the evidence if
the defence proposition is true. When the evidence is in the form of
measurements, methods are well-developed for multivariate, hierarchical
Bayesian multivariate random effects models. Methods are not so well
developed for discrete data.
Possible models for such data will be discussed. These models include a
beta-binomial model and its generalisation to a Dirichlet-multinomial
model, a Poisson-gamma model, an empirical model based on relative
frequencies. The seminar will be more of an introduction to a problem
and a discussion of possible approaches to a solution than an actual
The problem is motivated by data from a project in forensic phonetics at
the University of York in which the number of clicks per minute are
recorded for each of 100 speakers, over a period of time ranging from
four to six minutes. The evidence may be considered to be the number of
clicks from a piece of speech from an unknown source and the number of
clicks from a piece of speech from a known source, such as a suspect.
The prosecution proposition would be that these two pieces of speech
were made by the same speaker and the defence proposition would be that
they were made by different speakers.
Tea and coffee will be available after the seminar in the Mathematics
Common Room (5212).
This seminar series is a part of Maxwell Institute seminar series.
The seminar website:
There will also be a seminar on Friday 21 June, at 11am, by Prof Samuel
Oman (Hebrew University, Jerusalem), title to be confirmed
Dr Natalia Bochkina
Lecturer in Statistics
School of Mathematics
University of Edinburgh
Edinburgh, EH9 3JZ
Tel: 0131 650 8597
Email: [log in to unmask]
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