Table 3.

Correlation coefficients (P values) between the angle metrics and flashback quality metrics from 51 participants

Angle Metrics on Three Segments		Flashback Quality Metrics
		num_infil	FR	FE
$\overline{\alpha }$	${\overline{\alpha }}_S$	0.054 (0.18)	−0.192 (<0.001)	−0.238 (<0.001)
	${\overline{\alpha }}_{s1}$	0.152 (<0.001)	−0.118 (0.003)	−0.004 (0.91)
	${\overline{\alpha }}_{s2}$	0.044 (0.27)	−0.090 (0.024)	−0.173 (<0.001)
The number of angle changes (#angle_changes)	#angle_changess	0.473 (<0.001)	−0.528 (<0.001)	−0.440 (<0.001)
	#angle_changess1	0.110 (0.006)	−0.185 (<0.001)	−0.389 (<0.001)
	#angle_changess2	0.589 (<0.001)	−0.556 (<0.001)	−0.102 (0.01)
LDLJ(α)	LDLJ(α)s	−0.447 (<0.001)	0.463 (<0.001)	0.371 (<0.001)
	LDLJ(α)s1	−0.095 (0.018)	0.186 (<0.001)	0.580 (<0.001)
	LDLJ(α)s2	−0.513 (<0.001)	0.463 (<0.001)	−0.065 (0.11)

$\overline{\alpha }$, average insertion angle; #angle_changes, number of times the needle angle is changed; LDLJ(α), log dimensionless jerk of insertion angle.