Figure 3.

Didactic color-coded figure showing each possible situation when analyzing changes in measurements between 2 methods: uninterpretable (blue), noninterchangeable (red), in the gray zone of interpretation (orange), and interchangeable (green) (A). The last 3 points are shown with their interchangeability line and the limits of interchangeability lines. The same variations are depicted in the graphical representation for each situation in a 4-quadrant plot (B) and a polar plot (C). ΔRM = changes in reference method, ΔTM = changes in test method.