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April 2014
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Welcome to the
School of Mathematical Sciences

The University of Adelaide has a proud tradition of excellence in both teaching and research across the disciplines of Applied Mathematics, Pure Mathematics and Statistics.

Gary Glonek
Head of School
Nigel Bean
Director of Research
Deputy Head of School
Finnur Larusson
Director of Teaching

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Outlier removal using the Bayesian information criterion for group-based trajectory modelling
12:10 Mon 28 Apr, 2014 :: B.19 Ingkarni Wardli :: Chris Davies :: University of Adelaide

Attributes measured longitudinally can be used to define discrete paths of measurements, or trajectories, for each individual in a given population. Group-based trajectory modelling methods can be used to identify subgroups of trajectories within a population, such that trajectories that are grouped together are more similar to each other than to trajectories in distinct groups. Existing methods generally allocate every individual trajectory into one of the estimated groups. However this does not allow for the possibility that some individuals may be following trajectories so different from the rest of the population that they should not be included in a group-based trajectory model. This results in these outlying trajectories being treated as though they belong to one of the groups, distorting the estimated trajectory groups and any subsequent analyses that use them. We have developed an algorithm for removing outlying trajectories based on the maximum change in Bayesian information criterion (BIC) due to removing a single trajectory. As well as deciding which trajectory to remove, the number of groups in the model can also change. The decision to remove an outlying trajectory is made by comparing the log-likelihood contributions of the observations to those of simulated samples from the estimated group-based trajectory model. In this talk the algorithm will be detailed and an application of its use will be demonstrated.
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School of
Mathematical Sciences

Levels 6 and 7
Ingkarni Wardli Building
North Terrace Campus
The University of Adelaide
SA 5005 Australia

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Telephone: +61 8 8313 5407
Facsimile: +61 8 8313 3696