Evidence from Behavior INST 734 Doug Oard Module
Evidence from Behavior INST 734 Doug Oard Module 7
Agenda • Explicit feedback • Implicit Feedback Ø Link analysis • Clickstreams
Estimating Authority from Links Hub Authority
Simplified Page. Rank Algorithm (no teleportation) R(u): R(v): Bu: N V: Page. Rank score of page u Page. Rank score of page v set of pages that link to u number of links from page v
Page. Rank Algorithm Example 1/2 A 1/2 1 C B 1/2 1 1/2 D
R 2(A) = ½ x 2 + 1 x 2 = 5 R 1(A) = 2 1/2 A 1/2 1 C R 1(C) = 2 R 2(C) = ½ x 2 = 1 R 2(B) = ½ x 2 = 1 R 1(B) = 2 B 1/2 1 1/2 D R 1(D) = 2 R 2(D) = ½ x 2 = 1
R 3(A) = ½ x 1 + 1 x 1 = 2. 5 R 2(A) = 5 1/2 A 1/2 1 C R 2(C) = 1 R 3(C) = ½ x 5 = 2. 5 R 3(B) = ½ x 5 = 2. 5 R 2(B) = 1 B 1/2 1 1/2 D R 2(D) = 1 R 3(D) = ½ x 1 = 0. 5
Convergence R(A)’ = ½ x 2 + 1 x 1 = 4 R(A) = 4 1/2 A 1/2 1 C R(C) = 2 R(C)’ = ½ x 4 = 2 R(B) = 2 B 1/2 1 1/2 D R(D) = 1 R(D)’ = ½ x 2 = 1
Full Page. Rank Algorithm R(u): R(v): Bu: N V: N: c: Page. Rank score of page u Page. Rank score of page v set of pages that link to u number of links from page v total number of pages teleportation probability
“Link Farm” Spam 1 R(C) = 1 C 1 A R(A) = 1 2 2 3 3 … B 1 R(B) = 1 1 2 2 3 …
Agenda • Explicit feedback • Implicit Feedback • Link analysis Ø Clickstreams
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