11.07.2015 Views

Bayesian Linear Regression - CEDAR

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Machine Learning ! ! ! ! !SrihariSpecifying a Gaussian Process!• Key point about Gaussian Stochastic Processes!– Joint distribution over N variables y 1 ,.., y N is completelyspecified by the second-order statistics,!• i.e., mean and covariance!• With mean zero, it is completely specified bycovariance of y(x) evaluated at any two values of xwhich is given by a kernel function!E[y(x n ) y(x m )] = k(x n ,x m )• For the Gaussian Process defined by the linearregression model y(x,w)=w T φ (x) withprior p(w) = N(w|0,α -1 I) the kernel function is38K nm = k (x n ,x m ) = (1/α) φ(x n ) T φ (x m )!

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