Association Rules Flashcards
What type of learning are association rules?
Unsupervised
What is the task [T] within arules?
T: the co-occurence of patterns
What is the experience [E] within arules?
Presence of items in a sparse binary matrix
What is the performance measure [P] within arules?
There is no P, it is an unsupervised technique
Define Lift
An estimate of the association between two itemsets.
Define Support
Probability that a randomly chosen transaction contains two (or more) specific itemsets.
Define Confidence
The probability that one itemset has been chosen, given that another itemset has been chosen.
What is the notation for lift?
Lift(A=>B) = Pr(A,B)/Pr(A)Pr(B) = Pr(B|A)/Pr(B)
What is the notation for confidence?
How can you estimate the probability of observing an itemset from the data?
Simply, divide the count of the itemset, from the total number of transactions.
Pr(A) = n(a)/N
What is the notation for support?
S(A=>B) = Pr(A,B) = n(A,B)/N
Define frechet upper bounds.
Lift measures the extent…
To which A and B are not independant.
Lift has a minimum bound of … meaning …
- A lift of zero implies independance.
What is the definition of standardized lift?
