Online social network advertising platforms, such as that provided by LinkedIn, generally allow marketers to specify targeting options so that their ads appear to a desired de- mographic. Audience Expansion is a technique developed at LinkedIn to simplify targeting and identify new audi- ences with similar attributes to the original target audi- ence. We developed two methods to achieve Audience Ex- pansion: campaign-agnostic expansion and campaign-aware expansion. In this paper, we describe the details of these methods, present in-depth analysis of their trade-offs, and demonstrate a hybrid strategy that possesses the combined strength of both methods. Through large scale online exper- iments, we show the effectiveness of the proposed approach, and as a result, the benefits it brings to the whole market- place including both LinkedIn and advertisers. The achieved benefits can be characterized as: 1) simplified targeting pro- cess and increased reach for advertisers, and 2) better uti- lization of LinkedIn’s ads inventory and higher and more efficient market participation.

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Audience Expansion for Online Social Network
Advertising
Haishan Liu, David Pardoe, Kun Liu, Manoj Thakur,
Frank Cao, Chongzhe Li

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Ad Targeting Overview
User / Ad
Matching
Ad campaign
geo = na.us || na.ca
&& title = software engineer
&& skill = java || C++
&& comp != LinkedIn
...
Member profile
geo: na.us.ny
title: data scientist
skill: java, hadoop
company: LinkedIn
...
Ad Campaign Member Profile

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What is Audience Expansion?
Increase the reach of ad campaigns

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Why Audience Expansion
▪ Enumerating targeting options
is hard
▪ Order of magnitude
of
common targeting attributes
▪ Title: 10k
▪ Skill: 100k
▪ Group: 1 million
▪ Company: 10 million

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Goal of Audience Expansion
▪ For advertisers
▪ Increased reach
▪ Simplified targeting
▪ For LinkedIn
▪ Increased utilization of inventory
▪ Higher marketplace participation
▪ For members
▪ Minimal impact on experience

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More targeting options (groups, skills, schools, etc.)

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Audience Expansion Methodology Overview
● Two types of expansion work simultaneously
○ Campaign-agnostic expansion
■ Matches targeting criteria with expanded member profile
attributes
■ Takes effect immediately after the campaign launch
○ Campaign-aware expansion
■ Matches a campaign to members similar to the targeted audience
■ The expanded audience is calculated offline, which takes a few
hours

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Audience
EXACT MATCH BROADENED MATCH
- Company: Nationwide Children's Hospital
- Title: Research Associate
- Skill: Comparative genomics, BioStats
Standard Profile Expanded Profile
- Company: St. Jude Children's Hospital
- Title: Research Scientist
- Skill: Bioinformatics
Campaign-Agnostic Expansion

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Audience
EXACT MATCH LOOK-ALIKE AUDIENCE
- Profile similarity
- Behavior similarity
Campaign-Aware Expansion

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Audience Expansion in the Ads Serving Flow

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Profile Attribute Expansion by Similar-X
Profile company: LinkedIn Profile group
… Other profile attribute
expansionsFor each member
Campaign-agnostic expansion
Similar companies Similar groups
Facebook
Twitter
Google
Pinterest
Netflix
Amazon
Amazon
Salesforce
Expanded profile:

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Modeling Overview for Similar-X
Entity similarity
Field similarity

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Feature Extraction (E.g., LinkedIn)
▪ N-grams/phrases
▪ headline: Internet, professional, Social Network
▪ description: connection, productive, Talent Solution
▪ Standardized
▪ industry: Internet
▪ type: public company
▪ size: 5001-10000 employees

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Feature Extraction (E.g., LinkedIn)
▪ Derived
▪ skills: Software Engineering, Management, Marketing
▪ interests: professional identity, software development
▪ Network proximities
▪ view-browsemap: Facebook, Twitter, Pinterest
▪ occupation-browsemap: Google, Yahoo, Facebook

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Lookalike Expansion by Similar-Profiles
originally targeted members
For each campaign
Campaign-aware expansion
SWE at LinkedIn
with a Machine
Learning skill
Data Scientist at
Amazon with a
Data Mining skill

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Similar Profiles
▪ Problem size the square of
LinkedIn users
▪ Serves as an independent
product in LinkedIn Recruiter
▪ Enables Search By Ideal
Candidate as part of Next-Gen
Recruiter
▪ Powers Lead
Recommendations in Sales
Navigator

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Other Considerations - Campaign Selection
▪ A set of heuristics to identify campaigns that would likely to benefit
from campaign-aware expansion
▪ Must target a relatively specific audience using fine-grained attributes
▪ The size of the audience should not be extremely large
▪ The budget should be enough to afford additional impressions from
the expanded audience

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Other Considerations - Offline Matching
▪ Offline pipeline to emulate online ad/member matching
▪ Matches all active campaigns against all members (~460 million)
▪ Implemented as a massive map-reduce job with following
optimizations
▪ Use inverted campaign index as opposed to forward campaign index
used in online matching
▪ Use distributed cache to replicate campaign inverted index across all
mappers for matching
▪ Reduce the number of campaigns selected for matching by
considering only active campaigns

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Other Considerations - Post-Expansion Filters
▪ Remove following members from the expanded audience
▪ Negatively targeted
▪ Those violate the location, gender, or language criteria
▪ In addition, remove most expensive members
▪ Estimate member eCPC
▪ Regress historical bid distribution on profile attributes

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Other Considerations - Online-Offline Sync
Tc = -1
Tg = t1
campaign-aware
pipeline run
campaign
targeting
change
Tc = t2
Tg = t1
Tc > Tg
t1 t2 t3
Tc = t3
Tg = t1
Tc > Tg
Campaign targeting could change after the offline computation
time
campaign-aware
pipeline run
Offline results generated before t2 will be
invalidated until new results are generated after t3

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Effectiveness of Similar Profiles
▪ Compare network density
between original and expanded
audiences
▪ Baseline -- expand to active ads
clickers
▪ Expansion by Similar Profiles
achieves much higher network
density than baseline
denseraudience
more expansion

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Campaign-Member Fitness Score
▪ Campaign-member score
▪ The more similar members there
are in the targeted audience to an
untargeted member, the more fit
the untargeted member is to be
included in the expanded
audience.

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Evaluation and Results
Tuning a number of hyper-parameters through multiple A/B tests on a
fraction of members

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Online Evaluation
Relative changes in metrics compared to control. Statistically significant differences are in bold.
Relative changes in metrics when only considering impressions won by expansion-enabled campaigns.

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Impact of Audience Expansion to the Marketplace
Coverage: the number of delivered impressions as a percentage of the number of available
impressions, which measures how effective the ads inventory is utilized
Coverage increases in response to the Audience Expansion ramp-up

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Future Work
▪ Beyond Similar-X
▪ behavior-based similarity (ads click/share/like)
▪ collaborative-filtering
▪ Beyond targeting-based expansion
▪ Expand from optional seed lists

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Thanks For Your Attention!
Questions?