Market Basket analysis terminology In 1,000 video rental transactions with items A, B, C, and D, the probability that Video D is rented given that Video C is rented (P(D | C)) is called:

Difficulty: Easy

Correct Answer: Confidence.

Explanation:


Introduction / Context:
Association rule mining (Market Basket analysis) uses three core measures—support, confidence, and lift—to quantify relationships like “if C then D.” Understanding the difference between these measures is essential for evaluating cross-sell opportunities and designing promotions.


Given Data / Assumptions:

  • A dataset of 1,000 transactions includes videos C and D among other items.
  • We are interested in the conditional probability P(D | C).
  • We assume standard definitions used in association rule mining.


Concept / Approach:

Support measures how often items occur together: support(C ∧ D) = count(C and D) / total_transactions. Confidence measures the rule strength when the antecedent occurs: confidence(C → D) = support(C ∧ D) / support(C) = P(D | C). Lift normalizes confidence by the base rate of D: lift(C → D) = confidence(C → D) / support(D).


Step-by-Step Solution:

1) Translate the phrase “probability that D is rented given C is rented” into notation: P(D | C).2) Recall definitions: support = P(C ∧ D), confidence = P(D | C), lift = P(D | C) / P(D).3) Match the term to the definition: P(D | C) is confidence.4) Therefore, select “Confidence.”


Verification / Alternative check:

Any text on association rules (Apriori, FP-Growth) defines confidence as a conditional probability given the antecedent, aligning with P(D | C).


Why Other Options Are Wrong:

  • Basic probability: vague and not a standard metric here.
  • Support: joint occurrence frequency, P(C ∧ D), not conditional.
  • Lift: a ratio that compares confidence to the baseline frequency of D.
  • Conviction: another quality metric, not P(D | C).


Common Pitfalls:

  • Confusing support with confidence because both use counts.
  • Using high confidence rules with low support, leading to unstable insights.


Final Answer:

Confidence.

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