(1)The Bias-Variance Decomposition
[链接 1]http://chillyrain.is-programmer.com/posts/33766.html
[链接 2]https://github.com/lijin-THU/notes-machine-learning/blob/master/Pattern-Recognition-and-Machine-Learning/Chap-03-Linear-Models-for-Regression/03-02-The-Bias-Variance-Decomposition.ipynb
