Concept drift occurs when production data changes over time, causing a deployed model’s accuracy to gradually decay. It is common in real-world systems, especially those using user-generated data. section 6.1.2
Changing reviews and fraud patterns
A sentiment model trained on IMDb reviews collected in 2011 may perform worse on reviews from 2020 because vocabulary, expressions, and movie genres evolve. Fraud detection can drift even faster because fraud patterns may change daily. section 6.1.2
Respond to fast-moving drift by:
- Collecting current production data. section 6.1.2
- Annotating new examples and retraining the model continually when necessary. section 6.1.2






