Term tag: cross-validation

Cross-Validation (CV)

How cross-validation turns one lucky train/test split into a stable estimate, why 5 or 10 folds, and the leakage that quietly inflates every score.

Data Leakage

Data leakage is training a model on information it will not have at prediction time. It pushes scores up, not down, which is why review never catches it.

Feature Selection (FS)

Which columns to keep and how to decide: filter vs wrapper vs embedded, why 2^n subsets rules out brute force, and the CV mistake that fakes accuracy.