Question: Explain how error analysis by parts can be used to decide which component of the Siamese cat detector pipeline, the cat detector or the cat breed classifier, deserves more engineering effort.

Sample answer: Because the pipeline has two stages, a wrong final output could stem from either the cat detector failing to properly detect and crop the cat, or the cat breed classifier misclassifying a correctly cropped image. Error analysis by parts involves examining individual pipeline mistakes and tracing each one back to the responsible component: checking whether the crop itself was accurate, and if so, whether the breed classification on that crop was correct. By tallying how many errors originate from each stage, a team can see which component is contributing more mistakes and prioritize improvement work there rather than splitting effort evenly or years working on both.

Key points:

• Pipeline has two stages: cat detector and cat breed classifier
• Either stage can be the source of a final mistake
• Error analysis by parts traces individual errors back to their originating component
• Counting errors per component reveals which one needs more focus
• Purpose is to avoid spending years improving the wrong component

Rubric: Full credit explains that the pipeline has two potential error sources, describes tracing individual errors to the detector or classifier stage, and connects this to prioritizing engineering effort on the higher-error component.