Bias Variance Tradeoff

y_noise = np.var(y_test, axis=1)

    y_bias = (f(X_test) - np.mean(y_predict, axis=1)) ** 2

    y_var = np.var(y_predict, axis=1)

MSE = y_noise + y_bias + y_var

Proof : http://en.wikipedia.org/wiki/Bias%E2%80%93variance_tradeoff