Table 1. Comparison of conventional studies and this study, with respect to the utilized features.

Authors	Feature Extraction	Subject	Window Size	Features
Stewart and Allen [2]	Fast Fourier Transform (absolute power)	67 depression 60 healthy	2 seconds	Five frequency bands: delta (1−4 Hz), theta (4−8 Hz), alpha (8−12 Hz), beta (12−30 Hz), and gamma (30−50 Hz) 64-channel setup
Roh et al. [5]	Fast Fourier Transform	111 early depression 526 healthy	4.096 seconds, 50% overlap	Absolute theta (4–7.5 Hz), alpha (7.5–14 Hz), and beta (14–20 Hz) power; each frequency band; grand average of power spectra
Grin-Yatsenko et al. [6]	Current-Source Density (CSD) and Fourier-transform	54 subjects (before-after study)	60 seconds, 1.5seconds overlap	Asymmetry score from total alpha power
This study (Proposed method)	Fast Fourier Transform	40 depression 40 healthy	Whole HAMD session (approx. 40 minutes)	Individual Frequencies from 1 to 30Hz (FP1)