7.4 Practical Considerations

• Is it possible to identify all possible predictive interactions?

• Is it possible to evaluate all possible interactions?

• Should the interaction terms be created before or after the preprocessing part?

Only a fraction of all possible pairwise interactions contain relevant information.

With \(p\) predictors we have \((p)(p-1)/2\) pairwise interaction terms.

Here is the difference in interaction effects before and after preprocessing: