Feature scaling transforms numerical inputs into comparable ranges or scales. It commonly appears as a preprocessing step before a model, alongside feature engineering such as one-hot encoding. section 10.1.1 section 11.1.2
Use scaling with attention to the model and the surrounding pipeline:
- Include scaling consistently in the model pipeline so preprocessing forms part of the ordered path from input data to predictions. section 10.1.1
- Treat scaling as one option among numeric transformations, alongside normalization and mathematical functions such as logarithms. section 11.1.2
- Do not assume scaling improves every model: gradient boosting metrics may remain unchanged after monotonic transformations because decision trees are invariant to them. section 11.1.2
A simple classifier pipeline
A logistic regression classifier can be enhanced with a feature scaling step, producing a model pipeline that may also include one-hot encoding for categorical variables. section 10.1.1




