Simple effects, main effects, and interactions will be explained using the following data set:
Table 1. Effect of two N rates of fertilizer on grain yield (Mg/ha) of two barley cultivars.
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
= 1
Simple effect of A at b1 = a1b1 - a0b1
= 4 - 3
= 1
Simple effect of B at a0 = a0b1 - a0b0
= 3 - 1
= 2
Simple effect of B at a1 = a1b1 - a1b0
= 4 - 2
= 2