12. Copyright 息 2015 Criteo
Performance Advertising Setup
12
Advertiser
Publisher
1. User visits a publisher webpage
2. Bidders recieve real-time auction
3. Winner displays ad for advertiser
4. User converts on advertiser website
(click / sale / lead)
CPA
CPM
Bidder
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Performance Advertising Metrics
13
Ideally: number of sales 束 generated 損 by advertising for a given
budget
But difficult/costly to measure and optimize
E.g. incrementality A/B test
(also sales amount, margin etc)
Practically: number of sales attributed to advertising
Commonly: last click attribution
(also multi-touch, data driven etc)
14. Real-time bidding for performance
advertising
Key question : how much should we bid in the auction ?
15. Copyright 息 2015 Criteo
A little bit of game theory: 2nd price auctions
Sealed, 1 turn auction, winner pays the second highest bid
Value = 1
bid= 0,75
bid= 1,1
Value = 1
bid= 0,75
bid= 1,1
Competition:
0,5
Competition:
1,5
Case 1
Case 2
Value = 1
bid= 0,75
bid= 1,1
Competition:
1,05
Case 3
Value = 1
bid= 0,75
bid= 1,1
Competition:
0,8
Case 4
16. Copyright 息 2015 Criteo
Auction games
Second-price auctions
Dominant strategy: bid the expected gain (束 truthful auction 損)
An overbid means you are losing money
An underbid means you are losing potential revenue
Also: non-second price
Floors (hard/soft/dynamic)
17. Copyright 息 2015 Criteo
Baseline Bidding Policy
17
Under 2nd price auction hypothesis, dominant strategy is to bid
expected value
= 駒
束 Probability of post-click
attributed conversion 損
束 Value of a conversion 損
18. Copyright 息 2015 Criteo
Baseline Bidding Policy
18
Under 2nd price auction hypothesis, dominant strategy is to bid
expected value
= 駒
束 Probability of post-click
attributed conversion 損
束 Value of a conversion 損
Model quality/calibration impacts
revenue
19. Copyright 息 2015 Criteo
則 What can we use to predict clicks & sales?
則 User behavior on advertizers website
則 time since last visit
則 engagement level
則 last product seen, etc..
則 user fatigue: nb displays in last x days
Data features
則 Publisher:
則 publisher_id
則 url
則 display format
則 Campaign:
則 vertical_id: travel, classified, cars, etc
則 average ctr
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Learn on huge volumes of data
10 000 displays
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Learn on huge volumes of data
10 000 displays
leads to
50 clicks
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Learn on huge volumes of data
10 000 displays
leads to
50 clicks
leads to
1 sale
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Sizing of our prediction problems
則 Class unbalance: 0.5 / 100
則 N samples: 109
則 N raw variables: 102
則 N encoded features: 107
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Which algo to solve our problems?
Structured data
Lots of info in the data
High predictability
Highly structured info
Unstructured data
Poor predictability
Signal dominated by noise
Highly unstructured info
25. Copyright 息 2015 Criteo
則 Predict: P(Sales) = P(Click) P(Sales | Click)
則 P(Sales) ~ Bernoulli
則 Use (regularized) logistic regression
P(Y=1 | X) = 1/ (1+e-wTx)
則 Outputs a score in [0,1], interpreted as a probability
則 Negative log likelihood:
NLLH (y, p) = y log p (1 y) log (1 p)
Convex Optimization, using (cheap) 1+st order methods (SGD, L-BFGS, SAG, )
Optimizing for sales
26. Copyright 息 2015 Criteo
則 Vanilla Logistic Regression uses binary features only
則 Standard representation of categorical features: one-hot encoding
For instance, site feature
則 Dimensionality equal to the number of different values -- can be very large
則 Hashing to reduce dimensionality (made popular by John Langford in VW)
Hashing trick
cnn.com news.yahoo.com
0 0 01 0 0 0
h : string ! [0 . . . 2b
1]
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則 Outer product between two features; similar to a polynomial kernel of degree 2
則 Large number of values hashing trick.
則 Example: between site and advertiser,
Feature is 1 site=finance.yahoo.com & advertiser=bank of america
Quadratic features
Publisher network
Publisher
Site
Url
Advertiser network
Ad
Campaign
Advertiser
,
28. Copyright 息 2015 Criteo
Part II : Attribution Model for Bidding Performance
Joint work with Julien Meynet, Pierre Galland, Damien Lefortier
published at AdKDD & TargetAd workshop (KDD 2017)
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Outline
The problem: bidding in display advertising
Model:
Attribution model
Attribution aware bidder
Impact on offline evaluation metrics
Experience & results
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束 Post-click attributed conversions 損?
30
Display ad
impression
Paid search
click
Display ad
click
Email
open $$$
Last-click is the de facto attribution model
but advertisers are moving towards better attribution models:
Rule-based, uniform, linear, etc..
Data driven: regression, shapley value, etc..
But what is the impact from a bidders perspective?
What is the optimal bidding strategy right after a click?
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Attribution Probability Through Time Matters
32
Attributionprobability
givenconversion
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Attribution Model
33
How can we model probability of getting the attribution given there
will be a conversion?
: Post click conversion
: Attributed conversion
: Contextual features
: Delay click/conversion
= 1 = 1, = , = 隆) = 9: ; <
,
0Tapez une 辿quation ici.
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Conversion Modeling
34
Baseline solution:
0/1 prediction problem Logistic Regression
Large scale / latency constraint Hashing trick
= 駒 束 Probability of post-click
attributed conversion 損
But what are positives / negatives?
35. Copyright 息 2015 Criteo
From Attribution Model to an Attribution Aware Bidder
35
PQ 0 0 1
RS 1 3 1 3 1 3
VQ 1 0 0
WPP 1 1 1
WX 0.6 0.1 0.3
Cast the problem
as an internal
attribution
problem
36. Copyright 息 2015 Criteo
Attribution Aware Bidder: An Intuitive View
36
AB: previous click gives us the
attribution, only bid 束 marginal value 損
LCB: user is engaged, go for last-clickbidvalue
t
New display opportunity
37. Copyright 息 2015 Criteo
Attribution Aware Bidder
37
Baseline Last-click Bidder (LCB)
Attribution-aware Bidder (AB):
[: time elapsed since last click
= 駒 PQ = 1 = ) Tapez une 辿quation ici.
= 駒 WPP = 1 = ) 1 9: ; <b , Tapez une 辿quatio
Bid proportionally to the marginal contribution of the display
39. Copyright 息 2015 Criteo
Offline Evaluation of Bidders
39
Utility metric on logged
feedbacks:
Expected Utility: add uncertainty
on the cost distribution:
~ = 署h + 1,
k
= l(h h h)(k
h
h > h)
hs
Tapez une 辿quation ici.
k
h
h
h
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Attribution Aware Expected Utility*
40
Inject attribution function in the Utility:
基 k
, = l((h)h h)(k
h
h > h)
hs
Tapez une 辿quation ici.
Internal attribution function:
can be last-click, first click, etc..
can be the proposed attribution
model
* Evaluation of the proposed metric would require a
proper offline / online correlation analysis
42. Copyright 息 2015 Criteo
Offline Evaluation - Dataset
42
Log sampled from 30 days of Criteo traffic
Anonymized
Each line is an impression with:
Timestamp
Price paid
Contextual features (user, advertiser, publisher)
Click*, click position*, click number*
Conversion*, conversion value*
Attribution label (conversion was attributed to Criteo)
16M displays, 5M clicks, 800k conversions
Will be available at http://research.criteo.com/ soon
43. Copyright 息 2015 Criteo
Attribution Rates vs Time
43
Decay of attribution rate after a click
> 40% of conversions have
more than one click in the
preceding 30d
44. Copyright 息 2015 Criteo
Offline Evaluation Impact on Bid Profiles
44
Post-click bid profiles for 3 bidders:
Last-Click Bidder (LCB)
First-Click Bidder (FCB)
Attribution Bidder (基)
All models are learn using
regularized logistic regression
+ hashing trick
45. Copyright 息 2015 Criteo
Offline Evaluation Bidders Comparision
45
Results for 3 bidders on the Attribution Aware Expected Utility
瑞駒 告駒 基
Win Rate 0.94 0.90 0.89
W
, = 1000 2852 賊 43 2888 賊 43 賊
We limit user over exposure after a click
We get closer to lift-based bidding
We can reinvest budget on more profitable campaigns / more
incremental ads
46. Copyright 息 2015 Criteo
Online result
46
We tested online a simple modification of baseline through A/B
testing:
乞
(long term)
Revenue
(short term)
Advertiser
ROI
User ad
exposure
+. %
world wide
negative positive lower
暗 = 高暗 1 巨9:<b Tapez une 辿quation ici.
48. Copyright 息 2015 Criteo
Work in progress & Next steps
Better attribution modeling
Exponential decay is naive: build a better model (e.g travel
partners have different attribution schemes)
Model both conversion lift and attribution lift
Delayed feedback in both cases
Derive a robust (counterfactual) offline metric
50. Copyright 息 2015 Criteo
Questions?
References
Simple and Scalable Response Prediction for
Display Advertising, O. Chapelle, E. Manavoglu,
and R. Rosales, ACM TIST, 2013.
Offline Evaluation of Response Prediction in
Online Advertising Auctions, O. Chapelle,
WWW15
Attribution Modeling Increases Efficiency of
Bidding in Display Advertising, E. Diemert, J.
Meynet, P. Galland, D; Lefortier KDD17 TargetAd
workshop best paper finalist
http://labs.criteo.com
Articles on dev & science at Criteo
http://research.criteo.com
Conference reports & cutting edge science ;)
e.diemert@criteo.com