1. Diagnosing bias vs variance with cost vs degree of polynome degree plot

1) “The training error will tend to decrease as we increase the degree d of the polynomial. At the same time, the cross validation error will tend to decrease as we increase d up to a point, and then it will increase as d is increased, forming a convex curve.”

1) [ https://www.coursera.org/learn/machine-learning/supplement/81vp0/diagnosing-bias-vs-variance ]