Interpretations of directed information in portfolio theory, data compression, and hypothesis testing

Haim H. Permuter, Young Han Kim, Tsachy Weissman

Research output: Contribution to journalArticlepeer-review

Abstract

We investigate the role of directed information in portfolio theory, data compression, and statistics with causality constraints. In particular, we show that directed information is an upper bound on the increment in growth rates of optimal portfolios in a stock market due to causal side information. This upper bound is tight for gambling in a horse race, which is an extreme case of stock markets. Directed information also characterizes the value of causal side information in instantaneous compression and quantifies the benefit of causal inference in joint compression of two stochastic processes. In hypothesis testing, directed information evaluates the best error exponent for testing whether a random process Y causally influences another process X or not. These results lead to a natural interpretation of directed information I(Yn to Xn) as the amount of information that a random sequence Y n = (Y1,Y2, Yn) causally provides about another random sequence Xn = (X1,X 2,Xn). A new measure, directed lautum information, is also introduced and interpreted in portfolio theory, data compression, and hypothesis testing.

Original languageAmerican English
Article number5773045
Pages (from-to)3248-3259
Number of pages12
JournalIEEE Transactions on Information Theory
Volume57
Issue number6
DOIs
StatePublished - 1 Jun 2011

Keywords

  • Causal conditioning
  • Kelly gambling
  • causal side information
  • directed information
  • hypothesis testing
  • instantaneous compression
  • lautum information
  • portfolio theory

All Science Journal Classification (ASJC) codes

  • Information Systems
  • Computer Science Applications
  • Library and Information Sciences

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