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Greedy Model Averaging
Dong Dai · Tong Zhang

Mon Dec 12 10:00 AM -- 02:59 PM (PST) @
This paper considers the problem of combining multiple models to achieve a prediction accuracy not much worse than that of the best single model for least squares regression. It is known that if the models are mis-specified, model averaging is superior to model selection. Specifically, let $n$ be the sample size, then the worst case regret of the former decays at the rate of $O(1/n)$ while the worst case regret of the latter decays at the rate of $O(1/\sqrt{n})$. In the literature, the most important and widely studied model averaging method that achieves the optimal $O(1/n)$ average regret is the exponential weighted model averaging (EWMA) algorithm. However this method suffers from several limitations. The purpose of this paper is to present a new greedy model averaging procedure that improves EWMA. We prove strong theoretical guarantees for the new procedure and illustrate our theoretical results with empirical examples.

Author Information

Dong Dai (Rutgers University)
Tong Zhang (The Hong Kong University of Science and Technology)

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