Question 180
At Westhaven Retail, the commerce ML platform team maintains customer churn and inventory recommendation models under requirements for stable online features and production rollback. The production acceptance reviewer checks a proposed fix for: A marketing propensity model has a class distribution of 98 percent negative examples and selection by accuracy alone hides poor positive detection. Which observed result BEST demonstrates that the correction works?
Explanation
Correct Answer
The final report records positive-class recall and precision on the original distribution, not only inflated aggregate accuracy. This is observable proof for correction of: A marketing propensity model has a class distribution of 98 percent negative examples and selection by accuracy alone hides poor positive detection. The approved design change is: Measure class balance and compare stratified resampling or class weighting on training data while preserving an untouched evaluation set. The Westhaven Retail acceptance test separates measured ML behavior from an unverified implementation claim.
Incorrect Answers
The training schema references the intended version and a sampled stored record matches its declared transformation lineage. This would verify a different operation: Use explicit versioned feature names and document producer-consumer contracts for the stored feature definitions. That separate action addresses: A SageMaker Feature Store group publishes a transformed feature but training continues to read an older raw column with the same business label. It cannot establish the required Westhaven Retail correction for: A marketing propensity model has a class distribution of 98 percent negative examples and selection by accuracy alone hides poor positive detection. The decisive acceptance check is instead: The final report records positive-class recall and precision on the original distribution, not only inflated aggregate accuracy.
A field-type regression is quarantined and a compatible schema revision remains queryable with the expected typed attributes. This would verify a different operation: Register and validate an explicit schema or compatible evolution policy before promoting events into the curated training zone. That separate action addresses: A newly deployed Glue ingestion job tries to infer the schema of evolving JSON events, and a changed field type silently becomes a null column. It cannot establish the required Westhaven Retail correction for: A marketing propensity model has a class distribution of 98 percent negative examples and selection by accuracy alone hides poor positive detection. The decisive acceptance check is instead: The final report records positive-class recall and precision on the original distribution, not only inflated aggregate accuracy.
An approved source update appears within the freshness objective and replayed change messages do not create duplicate feature rows. This would verify a different operation: Introduce an appropriate CDC or streaming ingestion design that preserves update ordering and deduplicates repeated change events. That separate action addresses: A team uses a daily full-table export for near-real-time ML fraud features even though the source produces frequent small changes. It cannot establish the required Westhaven Retail correction for: A marketing propensity model has a class distribution of 98 percent negative examples and selection by accuracy alone hides poor positive detection. The decisive acceptance check is instead: The final report records positive-class recall and precision on the original distribution, not only inflated aggregate accuracy.