FOLLOW MY FRIENDS THIS FRIDAY!
An Analysis of Human-Generated Friendship Recommendations

Ruth García Gavilanes
Universitat Pompeu Fabra
Neil O´Hare, Yahoo! Research
Luca Maria Aiello, Yahoo! Research
Alejandro Jaimes, Yahoo! Research
Twitter: Users tweet recommendations
Advantages

Recommendations from friends
•  Trust
•  More

acceptances( Amin et al., Recsys’12)

•  Features unknown for machines
Disadvantages

•  Noise
•  Commercial purpose and Spam
•  Not all recommendations are delivered to

or seen by target users
Humans
Who-to-Follow Recommendations

We propose a way to measure the effect
of recommendations from humans only
In 2010
•  The most popular hashtag in 2010 was #followfriday

or #ff in several countries
•  Recommending people became trendy
•  No personalized recommendations of who to follow
What is Follow Friday?
TARGET USER

SOCIAL NETWORK RECOMMENDS
PEOPLE TO
FOLLOW ON FRIDAYS.

follows

Tie Strength
to follow or not to follow?
Objective
•  Analyze the dynamics of Follow Friday : impact,

effect in time, repetitions and longevity.

•  Identify important features in each recommendation

by using a classifier
Method
24 weeks
48 snapshots

RECEIVER

RECOMMENDER
Follows

ACCEPTED
RECOMMENDATION

RECOMMENDED
USERS

Who is new?
Follows

?

#followfriday
THURSDAY

FRIDAY

SATURDAY

SUNDAY

MONDAY

93% of follow friday Tweets

snapshot

snapshot
Acceptance
Total
Initial set of users

55,000

Receivers

0.60% instance acceptance

21,270

Recommenders

589,844

Recommended Users

3,261,133

Recommendation
Instances

59,055,205

Accepted
Recommendation
Instances

354,687

Most Follow Friday Recommendations
are not taken into account
right away
Interactions
Mentions

Acceptance
Rate

Recommender -> Recommendation

0.006

Recommendation <-> Recommender

0.009

Receiver -> Recommender

0.010

Recommender -> Receiver

0.011

Recommender <-> Recommendation

0.012

Receiver -> Recommendation

0.095

Recommendation -> Receiver

0.097

Receiver <-> Recommendation

0.145

Most Follow Friday Recommendations
are not taken into account
right away
IMPACT
Impact
•  We need to compare Follow Friday recommendations

to other models:

•  Implicit : Mentions that were not Follow Friday

recommendations

•  Unobserved : Follow Friday recommendations of the

future only

#FF
Acceptance after n weeks
Repetitions & Recommenders
Features
USER-BASED
(per user)

RELATION-BASED
(per pair)
• 

•  Attention
•  Followers vs Followees
•  Mentions by other users
•  Recommendations
•  Activity
•  Average tweets per
• 
day
•  New followees
•  Accepted
recommendations and
recommenders
•  Mentions

Tie Strength

–  Mentionss
–  Folllow Friday
recommendations
–  Previous
acceptances
–  Friendship longevity

Similarity

–  Words, mentions,
hashtags and urls
–  Geolocation

RECOMMENDATION-BASED
(per recommendation)
• 

Repetitions

• 

Format

–  Repeated
recommendations
–  Different recommenders
–  Day of the week
–  Re-tweet or not
–  Same tweet
recommendations
–  Urls
Methodology
•  Three methods: Rotation Forest, Linear combination and

random
•  Training : week 1 to 16
•  Test : week 17 to 23

•  Up to 2 weeks to calculate acceptance rate
•  Recommendations accepted after two weeks were not

considered in the classifier.
•  Balanced set for training
•  Goal : accepted recommendations towards the top of
the ranking
•  Evaluation with Mean Average Precision
Results
Ranking

MAP

Features

MAP

Rotation Forest

0.496

All

0.496

Linear
Combination

0.057

User-based

0.074

Relation-based

0.398

Random

0.037

Recommendationbased

0.062

User + Relation

0.518

User + Format

0.079

Relation + Format

0.379
Lessons Learned
•  Recommendations derived from Social Networks have an

impact on users decisions

•  Social accepted recommendations seems to last longer/

more relevant

•  Many broadcasted recommendations are not seen
•  Not accepted recommendations can be followed in the

future

•  Relation and user based features are better predictors of

tie formation
Future Work
•  Can we rate recommendations according to

permanence/tenure?

•  When should we consider an accepted

recommendation? (never vs. some day)

•  User study: Can we build an online recommender of

social recommendations (and so promote
recommendations not seen)?

•  Add cultural differences in features, is there an

improvement?
THANK YOU
@ruthygarcia

Follow My Friends This Friday! An Analysis of Human-generated Friendship Recommendations

  • 1.
    FOLLOW MY FRIENDSTHIS FRIDAY! An Analysis of Human-Generated Friendship Recommendations Ruth García Gavilanes Universitat Pompeu Fabra Neil O´Hare, Yahoo! Research Luca Maria Aiello, Yahoo! Research Alejandro Jaimes, Yahoo! Research
  • 2.
    Twitter: Users tweetrecommendations
  • 3.
    Advantages Recommendations from friends • Trust •  More acceptances( Amin et al., Recsys’12) •  Features unknown for machines
  • 4.
    Disadvantages •  Noise •  Commercialpurpose and Spam •  Not all recommendations are delivered to or seen by target users
  • 5.
    Humans Who-to-Follow Recommendations We proposea way to measure the effect of recommendations from humans only
  • 6.
    In 2010 •  Themost popular hashtag in 2010 was #followfriday or #ff in several countries •  Recommending people became trendy •  No personalized recommendations of who to follow
  • 7.
    What is FollowFriday? TARGET USER SOCIAL NETWORK RECOMMENDS PEOPLE TO FOLLOW ON FRIDAYS. follows Tie Strength to follow or not to follow?
  • 8.
    Objective •  Analyze thedynamics of Follow Friday : impact, effect in time, repetitions and longevity. •  Identify important features in each recommendation by using a classifier
  • 9.
    Method 24 weeks 48 snapshots RECEIVER RECOMMENDER Follows ACCEPTED RECOMMENDATION RECOMMENDED USERS Whois new? Follows ? #followfriday THURSDAY FRIDAY SATURDAY SUNDAY MONDAY 93% of follow friday Tweets snapshot snapshot
  • 10.
    Acceptance Total Initial set ofusers 55,000 Receivers 0.60% instance acceptance 21,270 Recommenders 589,844 Recommended Users 3,261,133 Recommendation Instances 59,055,205 Accepted Recommendation Instances 354,687 Most Follow Friday Recommendations are not taken into account right away
  • 11.
    Interactions Mentions Acceptance Rate Recommender -> Recommendation 0.006 Recommendation<-> Recommender 0.009 Receiver -> Recommender 0.010 Recommender -> Receiver 0.011 Recommender <-> Recommendation 0.012 Receiver -> Recommendation 0.095 Recommendation -> Receiver 0.097 Receiver <-> Recommendation 0.145 Most Follow Friday Recommendations are not taken into account right away
  • 12.
  • 13.
    Impact •  We needto compare Follow Friday recommendations to other models: •  Implicit : Mentions that were not Follow Friday recommendations •  Unobserved : Follow Friday recommendations of the future only #FF
  • 15.
  • 17.
  • 18.
    Features USER-BASED (per user) RELATION-BASED (per pair) •  • Attention •  Followers vs Followees •  Mentions by other users •  Recommendations •  Activity •  Average tweets per •  day •  New followees •  Accepted recommendations and recommenders •  Mentions Tie Strength –  Mentionss –  Folllow Friday recommendations –  Previous acceptances –  Friendship longevity Similarity –  Words, mentions, hashtags and urls –  Geolocation RECOMMENDATION-BASED (per recommendation) •  Repetitions •  Format –  Repeated recommendations –  Different recommenders –  Day of the week –  Re-tweet or not –  Same tweet recommendations –  Urls
  • 19.
    Methodology •  Three methods:Rotation Forest, Linear combination and random •  Training : week 1 to 16 •  Test : week 17 to 23 •  Up to 2 weeks to calculate acceptance rate •  Recommendations accepted after two weeks were not considered in the classifier. •  Balanced set for training •  Goal : accepted recommendations towards the top of the ranking •  Evaluation with Mean Average Precision
  • 20.
  • 21.
    Lessons Learned •  Recommendationsderived from Social Networks have an impact on users decisions •  Social accepted recommendations seems to last longer/ more relevant •  Many broadcasted recommendations are not seen •  Not accepted recommendations can be followed in the future •  Relation and user based features are better predictors of tie formation
  • 22.
    Future Work •  Canwe rate recommendations according to permanence/tenure? •  When should we consider an accepted recommendation? (never vs. some day) •  User study: Can we build an online recommender of social recommendations (and so promote recommendations not seen)? •  Add cultural differences in features, is there an improvement?
  • 23.