Anomaly Detective: T² & SPE

🕵️‍♂️ What are T² and SPE?

These are two "monitors" specifically responsible for catching "bad apples" in the data.

• Hotelling's T² (Internal Model Anomaly):

  • Imagine an ellipsoidal room (model space) where normal data plays.
  • T² anomaly: Points that run to the corners or even outside the wall. Although they are still within the model rules, they are isolated and strange.

• SPE (DModX) (External Model Anomaly):

  • Still that room, SPE measures the height of the point from the floor (residual).
  • SPE anomaly: Points floating in the air that completely violate the model rules, like ghosts.

📊 How to read?

Open the T² & SPE chart, and you will see:

1. Red Line (Limit): This is the warning line (95% or 99% confidence limit).
2. Points: Each point represents a sample.

• Any point exceeding the red line is a suspect! 🚨
• If points are in the top-right corner (both T² and SPE exceed limits), they are serious criminals and must be prioritized!

🛠️ How to use?

1. Quick location: Directly look at points outside the red line.
2. Lasso capture: Use the mouse to circle them.
3. View details: After selection, you can go to the "Data Removal" interface to see who they are (e.g., which row, what time the data is).