Wide & Deep Architecture and Model Evolution

~45 min read

The evolution from logistic regression to GBDT+LR to Wide & Deep to attention-based models, with a deep dive on what each component contributes and why joint training matters.

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Key points

  • GBDT+LR's key insight: gradient boosted trees automatically discover feature transformations and interactions that manual feature engineering misses — then LR combines them
  • Wide & Deep formally separates memorization (wide: logistic regression on sparse cross-features) from generalization (deep: MLP on embeddings) — joint training allows each component to specialize while the combined model benefits from both
  • DIN's key advance over W&D: attention over user history weighted by relevance to the current ad gives a dynamic user representation instead of a static average of all past interactions