Virtual Labs

Movie Review Sentiment Analysis using Naïve Bayes

What does the expression P(C|X) represent in the Naive Bayes classifier?

a: The probability of observing the words X in any document Explanation

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b: The probability of class C occurring in the dataset Explanation

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c: The probability that the review X belongs to class C Explanation

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d: The exact count of words in class C Explanation

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Which of the following best explains why Naive Bayes multiplies the probabilities of individual words?

a: Because each word increases the dataset size Explanation

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b: Because of the conditional independence assumption Explanation

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c: Because it improves vocabulary coverage Explanation

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d: Because multiplying probabilities improves accuracy automatically Explanation

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What problem does Laplace smoothing specifically solve in Naive Bayes?

a: Preventing underflow when multiplying many probabilities Explanation

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b: Assigning a non-zero probability to words not seen in the training data Explanation

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c: Ensuring all classes have equal probability Explanation

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d: Reducing the total number of features Explanation

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Why are log probabilities used instead of direct multiplication in Naive Bayes?

a: To simplify the model by removing all probabilities Explanation

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b: To convert classification into a clustering problem Explanation

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c: To avoid extremely small values that occur during probability multiplication Explanation

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d: To increase the overall classification speed Explanation

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Which preprocessing step most directly improves Naive Bayes’ ability to analyze sentiment?

a: Removing stopwords to reduce noisy, non-informative words Explanation

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b: Alphabetically sorting every sentence Explanation

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c: Using emojis to replace all punctuation Explanation

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d: Increasing the number of capital letters Explanation

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If the model predicts a negative review correctly, which term describes this outcome?

a: True Positive Explanation

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b: True Negative Explanation

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c: False Positive Explanation

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d: False Negative Explanation

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