 In factorial designs, thus two levels each of factor A and B in a factorial design, the main effects of two factors say A and B be can be calculated.The main effect of A is given by

formula_1

The main effect of B is given by

formula_2

Where n is total number of replicates.The letter "a" represent the factor combination of level 1 of A and level 2 of B and "b" represents the factor combination of A level 2 of A and level 1 of B.