Bias Variance Trade-Off: Overfitting and Underfitting

The inability of a machine learning model to truly capture the relationship in training data. As shown in the above models, M1 is unable to describe the relationship in training data, as well as M3, describe perfectly well. M2 describes in between them. It is nothing but the difference between the error in training data and testing data. As shown in the above models, M1, as well as M2, has low variance cause of the difference in errors and M3 has high variance.