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A Consistent Estimator of the Expected Gradient Outerproduct
Proceedings of the 30th Conference on Uncertainty in Artificial Intelligence, PMLR R12:872-881, 2014.
Abstract
In high-dimensional classification or regression problems, the expected gradient outerproduct (EGOP) of the unknown regression function f, namely EX $\nabla$f(X) \cdot $\nabla$f(X)$\top$ , is known to recover those directions v $\in$Rd most relevant to predicting the output Y . However, just as in gradient estimation, opti- mal estimators of the EGOP can be expensive in practice. We show that a simple rough estima- tor, much cheaper in practice, suffices to obtain significant improvements on real-world nonpara- metric classification and regression tasks. Fur- thermore, we prove that, despite its simplicity, this rough estimator remains statistically consis- tent under mild conditions.