When is accuracy a misleading metric?
PICTURE THIS: HOW TO EXPLAIN IT
Simple meaning
Accuracy looks strong on imbalanced data even if you always predict the majority class.
WHY — Metrics instead of guessing?
Why interviewers care about Metrics:
on Metrics.
the situation, the default choice, and one exception - that reads as experience.
Name the idea, why it exists, then one short example.
End with when you use it and one common pitfall.
STEPS — What happens step by step?
Before you speak the answer, walk the interviewer through these steps:
- 1Accuracy looks strong on
imbalanced data even if you always predict the majority class.
- 2It also hides whether
false positives or false negatives are more costly.
- 3Prefer precision, recall, F1,
ROC-AUC, PR-AUC, or a business cost.
- 4Give an example
One tiny concrete case you can say aloud.
- 5Common mistake
What juniors usually get wrong.
- 6Close
When you pick this over the alternative.
EXAMPLE — See it in action
Here's a short line you can speak, broken into clear beats:
Note: Adapt this scaffold to your own project — keep it under 60–90 seconds.
Key takeaway
Accuracy looks strong on imbalanced data even if you always predict the majority class. It also hides whether false positives or false negatives are more costly.