Table 3.

The summary of the FFT-based features used in EEG-based DDD.

Features	Mathematic Expression	References
Pure Band Equation (PBE)	θ/β	[44,50,56]
	θ/(α + β)	[51]
	(θ + α)/β	[44,51]
	(θ + α)/(α + β)	[44,51]
	θ/α	[73,79]
	δ/α	[73]
	α/β	[44,58,85]
	(0.6 * θ + 0.4 * α)/(0.5 * β)	[52,69]
	(α + β)/δ	[45]
	(δ + θ)/(α + β)	[48]
Relative Band Power (RBP)	$RBP\left(z_i\right)=\frac{Power\left(z_i\right)}{{{\displaystyle \sum }}_{i=1}^{5}Power\left(z_i\right)}\times 100\%$, where, zi = {δ, θ, α, β, γ}.	[19,61,66,82]
Log Band Power	$\mathrm{Log}M, \mathrm{where} M\in$ {8, 9, 10, 11, 12 Hz} or {10, 11, 12, 13, 14 Hz}	[26]
	Log(α − θ)	[71]