The simple effect of a factor is the difference between its two levels at a given level
of the other factor.
Simple effect of A at b0 = a1b0 - a0b0
= 2 - 1
= 1Simple effect of A at b1 = a1b1 - a0b1
= 4 - 1
= 3
Simple effect of B at a0 = a0b1 - a0b0
= 1 - 1
= 0
Simple effect of B at a1 = a1b1 - a1b0
= 4 - 2
= 2