PASCAL - Pattern Analysis, Statistical Modelling and Computational Learning

Practical Approaches to Principal Component Analysis in the Presence of Missing Values
Alexander Ilin and Tapani Raiko
(2008) Technical Report. Helsinki University of Technology, Espoo, Finland.


Principal component analysis (PCA) is a classical data analysis technique that finds linear transformations of data that retain maximal amount of variance. We study a case where some of the data values are missing, and show that this problem has many features which are usually associated with nonlinear models, such as overfitting and bad locally optimal solutions. Probabilistic formulation of PCA provides a good foundation for handling missing values, and we introduce formulas for doing that. In case of high dimensional and very sparse data, overfitting becomes a severe problem and traditional algorithms for PCA are very slow. We introduce a novel fast al- gorithm and extend it to variational Bayesian learning. Different versions of PCA are compared in artificial experiments, demonstrating the effects of regularization and modeling of posterior variance. The scalability of the pro- posed algorithm is demonstrated by applying it to the Netflix problem.

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EPrint Type:Monograph (Technical Report)
Project Keyword:Project Keyword UNSPECIFIED
Subjects:Computational, Information-Theoretic Learning with Statistics
Learning/Statistics & Optimisation
Theory & Algorithms
ID Code:4445
Deposited By:Tapani Raiko
Deposited On:13 March 2009