Table 1.

EEG reference model, unified estimator and schemes.

General reference model	vr = Hφ + e, e = Hε
Unified reference estimator	$\widehat{\phi }={\Sigma }_{\phi \phi }{\text{H}}^{\text{T}}{(\text{H}{\Sigma }_{\phi \phi }{\text{H}}^{\text{T}}+{\Sigma }_{\text{e}\text{e}})}^{+}{\text{v}}_r$
Prior of φ	${\Sigma }_{\phi \phi }={\alpha }^2{\text{I}}_{N_e}$		${\Sigma }_{\phi \phi }={\text{K}}_{\infty }{\Sigma }_{\text{j}\text{j}}{\text{K}}_{\infty }^{\text{T}}$
Solutions	$\widehat{\phi }={\text{H}}_{ar}\text{v}/(1+ns{r}_1)$		$\widehat{\phi }={\text{K}}_{\infty }·{\Sigma }_{\text{j}\text{j}}{\text{K}}_r^{\text{T}}{({\text{K}}_r{\Sigma }_{\text{j}\text{j}}{\text{K}}_r^{\text{T}}+{\Sigma }_{\text{e}\text{e}})}^{+}{\text{v}}_r$
Prior of j			${\Sigma }_{\text{j}\text{j}}={\beta }^2{\text{I}}_{N_s}$		${\Sigma }_{\text{j}\text{j}}\ne {\beta }^2{\text{I}}_{N_s}$
Sensor noise	zero	nonzero	zero	nonzero	nonzero
Reference schemes	AR	rAR	REST	rREST