Introduction
Machine learning models can perform well during testing but start making worse predictions when used in real life. This happens because the environment or data changes after the model is deployed. Understanding why models degrade helps keep them accurate and useful.
When your model's accuracy drops after deployment even though it worked well during training
When new types of data appear that the model has never seen before
When the real-world environment changes, like customer behavior or sensor conditions
When you want to monitor and maintain your model's performance over time
When you need to plan retraining or updating your model to keep it reliable