Difference between Novelty Detection and Outlier Detection?

Updated May 5, 2026

Short answer

Outlier detection includes anomalies in training; novelty does not[cite: 1].

Deep explanation

Outlier detection assumes training data is 'dirty'. Novelty detection assumes training data is 'pure' (normal only)[cite: 1].

Real-world example

Detecting a new animal species in a forest (novelty)[cite: 1].

Common mistakes

  • Training a novelty detector on data containing anomalies[cite: 1].

Follow-up questions

  • Which is harder?

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