What is the role of likelihood in Naïve Bayes classification?

Updated May 17, 2026

Short answer

Likelihood measures how probable observed features are given a class.

Deep explanation

Likelihood P(X|C) quantifies how likely features X are generated under class C. Naïve Bayes assumes conditional independence so likelihood becomes product of individual feature probabilities. This simplifies high-dimensional probability estimation.

Real-world example

Words like 'win', 'score' increase likelihood of sports category.

Common mistakes

  • Confusing likelihood with posterior probability.

Follow-up questions

  • Why multiply probabilities?
  • What is log-likelihood?

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