When should you manually engineer interaction features?
mediumAnswer
- For linear / logistic models, always — they can't discover interactions by themselves.
- For deep nets and gradient boosting, only in cases where you know a specific multiplicative or ratio structure matters .
- If a domain expert says 'this feature only matters when X is high', build the interaction explicitly.
- Trees find interactions automatically but they may need very many trees to capture them cleanly.
Check yourself — multiple choice
- Never — every model discovers interactions automatically
- Always for linear models; for GBM/NN when domain knowledge suggests a specific multiplicative/ratio form
- Only for text data
- Only for time series
Interactions: mandatory for linear, useful for GBM/NN when domain knowledge specifies structure.
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