Conference – 2018 Equation (14)

( π t π t e )=( c 1 c 2 )+( a( L ) b( L ) c( L ) d( L ) )( π t1 π t1 e )+( ε 1t ε 2t ) ( ε 1t ε 2t )~iid( ( 0 0 ),( σ 11 σ 21 σ 12 σ 22 ) )