DATABASE FUNDAMENTALS
DATA WAREHOUSING AND DATA MINING
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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Support(A B) / Support (A)
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Support(A B) / Support (B)
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Support(A B) / Support (A)
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Support(A B) / Support (B)
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Detailed explanation-1: -Confidence(A→B) = Probability(A & B) / Support(A)Note, confidence is the same as what is also known as conditional probability in statistics: P(B|A) = P(A & B) / P(A) Please beware of the notation.
Detailed explanation-2: -Confidence in a rule is calculated by dividing the probability of the items occurring together by the probability of the occurrence of the antecedent.
Detailed explanation-3: -The confidence of an association rule is the support of (X U Y) divided by the support of X. Therefore, the confidence of the association rule is in this case the support of (2, 5, 3) divided by the support of (2, 5).
Detailed explanation-4: -In specific, support of a rule A → B is the support of the union of A and B, which is the proportion of transactions that contain both A and B. Confidence is the proportion of transactions containing A also contains B.