http://yury.name

1. Economics
of Web-Design
Yury Lifshits
Caltech
http://yury.name
CS Club, Steklov Institute, 2008
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2. A camel is a horse designed by
a committee
Vogue’1958
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3. A camel is a horse designed by
a committee
Vogue’1958
Less is more
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4. A camel is a horse designed by
a committee
Vogue’1958
Less is more
1855, Robert Browning
(English poet)
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5. Outline
1 Anti-AdWords Theorem
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6. Outline
1 Anti-AdWords Theorem
2 Dynamic Design
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7. Outline
1 Anti-AdWords Theorem
2 Dynamic Design
3 Hit Counter Project Proposal
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8. 1
Anti-AdWords Theorem
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9. Problem Statement
Given 10 organic search results
and 5 sponsored results
place them on 15 slots on a webpage
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10. Math model (1/2)
Every link i:
Price pi
Relevance ri
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11. Math model (1/2)
Every link i:
Price pi
Relevance ri
Attractiveness ai
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12. Math model (1/2)
Every link i:
Price pi
Relevance ri
Attractiveness ai
Every slot j:
Attention share sj
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13. Math Model (2/2)
Matching M:
Place every link i to slot j = M(i)
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14. Math Model (2/2)
Matching M:
Place every link i to slot j = M(i)
User clicks on link i
with probability proportional to
sM(i) + ai
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15. Payoffs
Expected relevance:
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16. Payoffs
Expected relevance:
15
Rel(M) = (sM(i) + ai) · ri
i=1
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17. Payoffs
Expected relevance:
15
Rel(M) = (sM(i) + ai) · ri
i=1
Expected revenue:
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18. Payoffs
Expected relevance:
15
Rel(M) = (sM(i) + ai) · ri
i=1
Expected revenue:
15
Rev(M) = (sM(i) + ai) · pi
i=1
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19. Payoffs
Expected relevance:
15
Rel(M) = (sM(i) + ai) · ri
i=1
Expected revenue:
15
Rev(M) = (sM(i) + ai) · pi
i=1
Attractiveness is not important 8 / 35

20. Pareto-Optimal Matching
M is Pareto-Optimal iff there is no M such that
Rel(M) < Rel(M ), Rev(M) < Rev(M )
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21. Pareto-Optimal Matching
M is Pareto-Optimal iff there is no M such that
Rel(M) < Rel(M ), Rev(M) < Rev(M )
Otherwise M is stupid
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22. Example (1/2)
Attention Link Relevance Price
50% O1 2 -
40% A1 0 25$
10% A2 1 20$
1.1 12$
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23. Example (2/2)
Attention Link Relevance Price
50% A2 1 20$
40% O1 2 -
10% A1 0 25$
1.3 12.5$
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24. Anti-AdWords
Left — organic, right —
advertising
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25. Anti-AdWords
Left — organic, right —
advertising
Under presented model
AdWords design can be stupid
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26. Anti-AdWords
Left — organic, right —
advertising
Under presented model
AdWords design can be stupid
That is, another presentation
can improve both relevance
and revenue
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27. Notation
Page attention structure P:
20% 18% 15% . . . 4% 2%
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28. Notation
Page attention structure P:
20% 18% 15% . . . 4% 2%
Fixed design D:
Ad slots, organic slots
20% 18% 15% . . . 4% 2%
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29. Anti-AdWords Theorem
∀P ∀∗ D
∃ links L such that
any matching M ∈ D
is stupid for L
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30. Alternative to AdWords
Single list for sponsored and
organic results
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31. Alternative to AdWords
Single list for sponsored and
organic results
Tradeoff ranking
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32. Further questions
Do we need to keep 10 Organic
guarantee?
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33. Further questions
Do we need to keep 10 Organic
guarantee?
Adwords redundancy?
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34. Further questions
Do we need to keep 10 Organic
guarantee?
Adwords redundancy?
Quantify possible Adwords
inprovements
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35. Further questions
Do we need to keep 10 Organic
guarantee?
Adwords redundancy?
Quantify possible Adwords
inprovements
Find all rankings on a trade-off
curve
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36. 2
Dynamic Design
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37. Increase Key Numbers
Owners utility
User utility
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38. Key Numbers for Owner
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39. Key Numbers for Owner
Ad revenue
Number of users
Volume of content
Amount of feedback
User time online
Brand recognition
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40. Key Numbers for User
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41. Key Numbers for User
# of matches (dating)
# of job offers
# of answers (QA)
# interesting stories (news)
# of compliments (social
networks)
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42. Design
=
tool for increasing
key numbers
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43. Main Challenge
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44. Main Challenge
Quantify Design
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45. Design Decisions
What to display
With what priorities?
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46. Quantify Internal Priorities
Attention budgets and auctions
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47. Dynamic Design
Choices based on opportunity
(user, action, time) knowledge
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48. Design Mechanisms
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49. Design Mechanisms
Chosen by owner
Fresh
User voted
Random
Personalized
Paid
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50. Minimalism?
Design complexity = # of links
Links with CTR < .001 are worse
than ads
One random big instead many
static small
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51. Links to kill
Amazon: “Add to wedding registry”
Google: “Report yourself”
Yahoo: “Horoscopes”
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52. Django MTV Tricks
Template inheritance
If/for loops in templates
Exceptions
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53. 3
Hit Counter Project Proposal
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54. Hit Analysis
Easy: incoming hits
Hard: outgoing hits
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55. Outgoing Hits
Ajax solution
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56. Outgoing Hits
Ajax solution
Can be blocked
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57. Outgoing Hits
Ajax solution
Can be blocked
Inverted index
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58. Outgoing Hits
Ajax solution
Can be blocked
Inverted index
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59. Outgoing Hits
Ajax solution
Can be blocked
Inverted index
Internal hits only
Goto
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60. Outgoing Hits
Ajax solution
Can be blocked
Inverted index
Internal hits only
Goto
Bad for SEO
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61. Call for Feedback
Volunteers for hit counter
project?
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62. Links
http://yury.name
Homepage
http://yury.name/newweb.html
Tutorial “The New Web”
http://yury.name/reputation.html
Tutorial “Reputation Systems”
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63. Thanks for your attention!
Questions?
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