7.2 Method to Calculate Net Interaction Effects

Three step process:

1. Compute additive contribution of each variable (i.e., deviation from global mean)
   
2. Calculate net effect of interaction for each pairwise combination:
   • Determine the contribution for each pair of explanatory variables, PC (paired contribution)
   • Compute additive contribution for single variable 1, SC1 (single contribution 1)
     
   • Calculate additive contribution for single variable 2, SC2 (single contribution 2)
     
   • Putting together, net interaction effect = PC - SC1 - SC2
3. Rank contributions for both individual variables and pairwise interactions using the absolute value of the contribution effects. Use ranking for ordering variable importance calculations.