Example with an interaction:
Table 2. Effect of two N rates of fertilizer on grain yield (Mg/ha) of two barley cultivars.
Fertilizer Rate (B)
Cultivar (A)
0 kg N/ha (b0)
60 kg N/ha (b1)
Larker (a0)
1.0 (a0b0)
1.0 (a0b1)
Morex (a1)
2.0 (a1b0)
4.0 (a1b1)
The simple effect of a factor is the difference between its two levels at a given level of the other factor.