Table 2.

Specification of the four types of spatio-temporal interaction considered in terms of the Kronecker product of the two matrices representing the structure of the spatial and temporal effect, respectively

Type of spatio-temporal interaction	$R_{\delta }$
I	$I_s\otimes I_t$
II	$I_s\otimes R_t$
III	$R_s\otimes I_t$
IV	$R_s\otimes R_t$

The matrix $I_s$ ($I_t$) represents the identity matrix, which corresponds to the unstructured spatial (temporal) effect, whereas $R_s$ ($R_t$) represents a non-identity matrix that corresponds to a specific structured spatial (temporal) effect