Bioinformatics Advance Access published online on March 4, 2009
Bioinformatics, doi:10.1093/bioinformatics/btp109
MIST: Maximum Information Spanning Trees for Dimension Reduction of Biological Data Sets
1Computer Science and Artificial Intelligence Laboratory, 2Department of Biological Engineering, 3Department of Electrical Engineering and Computer Science Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA
*To whom correspondence should be addressed. Dr. Bruce Tidor, E-mail: tidor{at}mit.edu
| Abstract |
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Motivation: The study of complex biological relationships is aided by large and high-dimensional data sets whose analysis often involves dimension reduction to highlight representative or informative directions of variation. In principle, information theory provides a general framework for quantifying complex statistical relationships for dimension reduction. Unfortunately, direct estimation of highdimensional information theoretic quantities, such as entropy and mutual information (MI), is often unreliable given the relatively small sample sizes available for biological problems. Here we develop and evaluate a hierarchy of approximations for high-dimensional information theoretic statistics from associated low-order terms, which can be more reliably estimated from limited samples. Due to a relationship between this metric and the minimum spanning tree over a graph representation of the system, we refer to these approximations as MIST (Maximum Information Spanning Trees).
Results: The MIST approximations are examined in the context of synthetic networks with analytically computable entropies and using experimental gene expression data as a basis for the classification of multiple cancer types. The approximations result in significantly more accurate estimates of entropy and MI, and also correlate better with biological classification error than direct estimation and another low-order approximation, minimum-redundancy-maximum-relevance (mRMR).
Availability: Software to compute the entropy approximations described here is available as Supplementary Material.
Contact: tidor{at}mit.edu
Associate Editor: Dr. Jonathan Wren
Received on October 5, 2008; revised on February 9, 2009; accepted on February 22, 2009