A small gain.
A careful reading.
| Fold | Baseline AUC | Blend AUC |
|---|---|---|
| 2 | 0.961215 | 0.961287 |
| 3 | 0.960963 | 0.960997 |
Fixed 30% CatBoost blend. AUC is not accuracy. These are not untouched final-test estimates.
PROJECT 03 / COMPETITION MODELLING · PYTHON · CATBOOST
Saved validation and submission results · Exploratory competition study
Does a more complex model add a reliable improvement?
Can CatBoost add useful information to an existing airline-satisfaction model? I compared a fixed blend across validation folds, then checked whether the result carried through to a competition submission.
The input is Kaggle’s Playground Series S6E10 competition data. Its generated records are a modelling benchmark, not an airline’s operational customer survey. The task predicts satisfaction; it does not identify what would cause a passenger to become satisfied.
A fixed blend combines 70% of the existing tree/neural predictions with 30% CatBoost predictions. CatBoost uses native categorical inputs, additional rating categories and route-distance features. Competition target encodings are cross-fitted inside each outer training fold.
The retained confirmation code evaluates folds 2 and 3 after development on fold 1. Early stopping uses outer validation labels, and those folds have prior screening history. These are exploratory checks, not untouched final-test evidence.
SAVED EXPERIMENT 75 · ROC AUC
The saved three-fold mean blend AUC is 0.961105. The later submitted blend scored 0.96066 on the public leaderboard, below the previous own-model submission of 0.96071. The small validation gain did not translate into a public-score improvement. ROC AUC measures ranking discrimination, not percentage accuracy.
A model can add complementary predictions in validation without improving the submitted result. I kept the stronger existing submission rather than promoting the weaker candidate. Further work needs a fresh evaluation design and a meaningful gain against the exact retained best before spending more compute. A production decision would also need calibration, error analysis and a clear use case.
The saved account-best public AUC is 0.96188 from a separate community-assisted ensemble using published prediction inputs and my own model components. It is not the CatBoost result or an independently developed end-to-end model. Public leaderboard scores and cross-validation scores use different evaluation data; no current rank or final private-test result is claimed.
The code and saved review are retained evidence. The code depends on earlier feature preparation and model predictions from the original experiment environment; it is not a standalone training pipeline. The later submitted blend is documented in the saved submission review. Training was not rerun during this website review.
| Fold | Baseline AUC | Blend AUC |
|---|---|---|
| 2 | 0.961215 | 0.961287 |
| 3 | 0.960963 | 0.960997 |
Fixed 30% CatBoost blend. AUC is not accuracy. These are not untouched final-test estimates.