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Module 3: Classification and Prediction

20242m

Which of the following classifiers uses a probabilistic approach to classification?

(i) Decision tree
(ii) Support vector machine
(iii) Naive Bayes
(iv) KNN

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Answer: (iii) Naive Bayes

Naive Bayes is explicitly probabilistic: it applies Bayes' theorem, P(C∣X)=P(X∣C) P(C)P(X)P(C \mid X) = \dfrac{P(X \mid C)\,P(C)}{P(X)}, assuming naively that features are conditionally independent given the class, and predicts the class with the maximum posterior probability. Its output can be read directly as class probabilities.

A decision tree chooses splits by information gain or Gini impurity — a deterministic, rule-based model — and an SVM finds a maximum-margin hyperplane by convex optimisation, not by a probability model. KNN does give a rough frequency estimate through neighbour voting, but it has no underlying probabilistic model; the unambiguously probabilistic classifier here is Naive Bayes.

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