SPE Plot (DModX)

🕵️‍♂️ What is this?

This is the external "monitor" of the model.

It measures how far a sample point is from the model plane (residual). If a point has a large SPE, it means it doesn't belong to this model at all (ghost data).

🧐 How to read?

• Red Line (Limit): This is the warning line (95% or 99% confidence limit).
• Points:
  • Below red line: Normal, everyone stays close to the plane.
  • Above red line: Abnormal, floating in the air, completely unpredictable.

🛠️ How to use?

Note: This chart has a lasso function for selecting abnormal parameters.

• Catch model outliers: If a point has a very high SPE, it means this sample is very strange, possibly a new pattern (such as a process change).
• Combine with T²: If T² is normal but SPE is high, it's a new anomaly.