Table 2.

Differences in brain wave amplitude of several frequency bands between pain levels.

Pain levels to compare	Frequency(Hz)	P value
None vs Moderate	1 Hz	0.003
	2 Hz	0.002
None vs Severe	5 Hz	0.005
	6 Hz	0.008
	11 Hz	0.036
	12 Hz	0.016
	13 Hz	0.008
	14 Hz	0.007
	15 Hz	0.011
	16 Hz	0.031
	18 Hz	0.034
	24 Hz	0.050
Mild vs Moderate	1 Hz	0.001
	2 Hz	< 0.001
Mild vs Severe	12 Hz	0.030
	14 Hz	0.036
	15 Hz	0.039
Moderate vs Severe	2 Hz	< 0.001
	4 Hz	0.010
	11 Hz	0.041
	12 Hz	0.026
	13 Hz	0.035

Amplitude power in each frequency was compared among quartile pain levels.

The amplitude power of 10 frequency bands was significantly different between pain levels “None” and “Severe”. Similarly, 2 bands, 3 bands, 2 bands and 5 bands were significantly different between pain levels “None” and “Moderate”, “Mild” and “Severe”, “Mild” and “Moderate” and “Moderate” and “Severe”, respectively. There were no significant between “None” and “Mild”.

Statistical analysis was undertaken using Student’s t-test and the resultant p values were corrected by Bonferroni correction to evaluate the significance.