Fig. 4.

Cubic spline regression graphs with chosen cut-off values. (NB: please note different scales on y axes).

Fig. 4a	Fig. 4b
1P KJC3	2P KJC3
Reader 1 (NKA): 178.0–182.5°	Reader 1 (NKA): 180.5–184.5°
Reader 2 (LMG): 177.5–182.5°	Reader 2 (LMG): 180.5–185.5°
Reader 3 (MTS): 178.0–182.0°	Reader 3 (MTS): 180.0–185.5°
Mean: 177.8–182.3°	Mean: 180.3–185.0°
Rounded to: 178.0–182.0°	Rounded to: 180.0–185.0°