Data drift is a change in incoming data that can make an ML model perform worse while it keeps running. For example, fake reviews can distort a recommendation system over time. Monitoring helps teams detect poor performance and adjust the model or retrain it. section 3.4.6
Text data makes drift especially difficult to assess: language representations are approximations, and correctness and data cleanliness can be hard to define. section 3.2.5
Monitor data entering and leaving the model, and consider signals such as:
- Missing values, uniqueness, and shifts in standard deviation. section 3.4.6
- Differences by segment, such as region or A/B test group. section 3.4.6











