Question: A team is debugging a document-processing system with three stages: image cleanup, text detection, and final classification. They review the development set mistakes and assign each mistaken example to the single stage that most likely caused it. Explain why this kind of analysis is useful and how the resulting error shares help the team decide what to work on first.

Sample answer: By sorting development set mistakes into the pipeline stage most responsible for each one, the team can estimate how much of the total error comes from each stage. This makes it easier to see which part of the system is contributing the largest share of failures. The stage with the largest error share is the best place to direct improvement effort, because fixing it is likely to produce the biggest gain.

Key points:

• Assign each mistake to one responsible pipeline stage
• Measure the share of errors associated with each stage
• Use those shares to choose the highest-priority improvement target

Rubric: The answer should say that each error is assigned to one pipeline stage. It should explain that this allows the team to estimate the fraction of errors caused by each stage. Finally, it should describe how those fractions are used to decide where to focus improvement work.