Biad-Variance trade-off


  • Bias: Error due to erroneous or overly simplistic assumptions, underfitting. The error rate on the training set.
  • Variance: Too much complexity, sensitive to high degrees of variation, overfitting. The error rate between the training and the validation set.

How can I act if I have different kinds of high/low bias/variance scenarios

High Bias:

  • Increase model size (usually with regularization to mitigate high variance)
  • Add more helpful features (which is another way of increasing again model size)
  • Remove (Worse) / reduce (Better) regulaization
  • Adding more training data wont help...the model is too "small"

High variance:

  • Add training data (usually with a big model to handle them)
  • Add/increase regularization
  • Early stopping for NN
  • Remove features (make the model simpler)
  • Decrease model size (prefer regularization)
  • Add more helpful features that are more useful to the problem at hand instead of the ones you have

Can I have both low variance-low bias or high bias-high variance?

Last updated on 20th Aug 2019