EMS SSA I- A E SS EMS E B 2 B b-1 b-1 SS EMS=E 2 (a-1)(b-1) MSA MS B 1 MS MS( )( ) eB 2 eA 1 e 2 e j 2 2 j B B i 2 2 i A A MS MS F MS MS F a 1 b 1 SS EMS E b 1 a b 1 SS EMS E a 1 b a 1 SS EMS E  = =  =       − − = +  −   =      − = +  −   =      − =  