Essay

Explain why different training and evaluation distributions can be appropriate.

Question: In a concise analytical response, explain why a cat classifier might train on internet images plus mobile images while using only mobile images for dev and test sets.

Sample answer: The additional internet images can help train a data-hungry algorithm by providing a much larger training set. However, user-uploaded mobile images closely reflect the actual distribution on which the app must perform well. Dev and test sets should therefore contain mobile images so that evaluation measures the desired future performance. This creates different training and dev/test distributions by design.

Key points:

  • Internet images provide additional training data.
  • Mobile images represent the actual distribution of interest.
  • Dev and test sets should reflect expected future data.
  • Training and dev/test distributions can intentionally differ.

Rubric: A strong response identifies the value of auxiliary internet data, identifies mobile images as the target distribution, connects dev/test selection to future performance, and explains why the resulting distributions differ.

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Updated 2026-07-19

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Machine Learning

Deep Learning

Supervised Learning

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Data Science

Machine Learning Strategy

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