Editing Machine learning (section)

=== Overfitting ===
{{Main|Overfitting}}

[[File: Overfitted Data.png|thumb|The blue line could be an example of overfitting a linear function due to random noise.]]
Settling on a bad, overly complex theory gerrymandered to fit all the past training data is known as overfitting. Many systems attempt to reduce overfitting by rewarding a theory in accordance with how well it fits the data but penalising the theory in accordance with how complex the theory is.{{sfn|Domingos|2015|loc=Chapter 6, Chapter 7}}