Question: If you have a training error of 15% and an optimal error rate of ~0%, what does this suggest about the potential fruitfulness of bias-reducing changes?

Sample answer: It suggests that bias-reducing changes might be highly fruitful because the 15% gap leaves much room for improvement in the classifier's bias.

Key points:

• Much room for improvement.
• Bias-reducing changes might be fruitful.

Rubric: The answer should indicate that bias-reducing changes are likely to be fruitful due to the large amount of room for improvement.