A probabilistic view of Bayesian Nonparametrics – stickbreaking, Pitman-Yor Processes and the Poisson Calculus
INCEPTION OF IDEAS
NEW seminar series where innovation begins
Organized by Business Analytics Group of IIM
Prof. Lancelot James
Chair Professor of Business Statistics
Department of Information Systems, Business Statistics and Operations Management
HKUST Business School
At the heart of Bayesian statistics lies the concept of conditional probability. The notion of a posterior distribution enables us to probabilistically incorporate our prior beliefs about unknown quantities with informative data. This is fundamental in Bayesian machine learning, facilitating applications in topic models, recommendation systems, and natural language processing.
The Dirichlet multinomial framework serves as a classic and important example of a flexible Bayesian model. Bayesian nonparametric statistics elevates this from random vectors to the calculus of random measures, with the Dirichlet process (DP) as a seminal contribution. My work has focused on advancing modelling capabilities beyond the DP, enhancing practical applications and formal analyses.
In this talk, I will explore the origins of the Poisson Partition Calculus, a method I developed for analyzing a wide range of processes, beginning with a 2002 arXiv preprint and culminating in a series of papers. I will also highlight my highly influential collaborations with Hemant Ishwaran (2001 JASA) on topics we named and popularized: stick-breaking priors and Pitman-Yor processes, which have roots in more esoteric excursion theory.
Underlying this discussion is how I have been influenced by great and generous people throughout my career, starting with my advisor Albert Lo.
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I. 2002 ArXiv preprint on the Poisson Partition Calculus (hard read)
Some important papers related to that (in chronological order)
- Bayesian Poisson process partition calculus with an application to Bayesian Lévy moving averages (projecteuclid.org)
- Posterior Analysis for Normalized Random Measures with Independent Increments – JAMES – 2009 – Scandinavian Journal of Statistics – Wiley Online Library
- Bayesian Poisson calculus for latent feature modeling via generalized Indian Buffet Process priors (projecteuclid.org)
II. Joint work with Hemant Ishwaran -related to stickbreaking and Pitman Yor processes. JASA 2001