SocialCircuits:
The Art of Using Mobile Phones for
Modeling Personal Interactions
Wayne Stilwell
CS 595
September 29, 2011
What is it?
Platform that uses mobile phones and
surveys to capture relationships and
influences in a dense community
 Mobile phones track interaction with
others
 Surveys track changes in habits, opinions,
and health

Experiment at a glance
Deployed on a
“physically and
socially distant”
college dorm in the
2009-2010 school
year
 Over 65 of 90
students participated
 Some declined due
to privacy concerns

65% of residents said
most of their
friends/contacts lived
in the dorm
 Data captured:

◦ 3 million co-location
samples
◦ 60,000 phone calls
◦ 20,000 text messages
Devices used

Based on Windows Mobile 6
◦ Students transferred existing voice plans
Tested on Verizon, AT&T, Sprint, and TMobile
 Works on 6 different smart-phones
 Source code available at:
http://mob.media.mit.edu

System capabilities
Detect nearby Bluetooth devices
 Detect WiFi access points
 Log phone calls and text messages
 Background scan manager

◦ Ensures Bluetooth and WiFi are activated

On-device survey launcher
◦ Launches daily surveys when phone is turned
on
System capabilities

On-device user feedback engine
◦ Students could respond to other’s responses


Over-the-air application updater
Custom Music Player
◦ Students could play, share, rate, and search
through a library of 1500 tracks

Flexible integration with web-based survey
◦ MySQL tables generated for each user for data
analysis
Study: Political opinions
Goal is to see how our opinions diffuse
across our social networks
 Surveyed students 3 times (each month
before the election)

◦ Asked their interest in politics & party
preference

Based on these results, and who a student
interacted with, they could predict if that
person is likely to accept or reject new
opinions
Tips for future attempts

Mobile phone sensors
◦ Using GPS and Bluetooth to track location
and proximity are useful, but both must be
enabled
◦ Accelerometers are less accurate if the phone
does not remain at a fixed spot on the body
Tips for future attempts

Platform Openness, Cross-Carrier
Support
◦ Only a jail-broken iPhone could run this
platform at the time
◦ For a large-scale experiment, just use a single
app (instead of manually installing software on
hundreds of phones)
Tips for future attempts

Community Selection
◦ Density is more important than volume
◦ Want to track as many reasons as you can
why someone’s behaviors changed
Tips for future attempts

Community Preparation
◦ Some were concerned about privacy
 Ironically their concerns “diffused” to others
◦ Personal identifiers in data were hashed,
disguised, and removed
◦ Some were uncomfortable doing the surveys.
So they were not mandatory.
◦ Students were also paid $1/day each time they
filled out a survey.
Tips for future attempts

Long-Term Reliability
◦ Get help on the ground
◦ Encourage participants to report problems
 Students offered $10 to be first to report a bug
◦ Use minimal amount of handsets
 More handsets = more costly bugs
◦ Avoid on-device flash memory
 They wrote every 5 minutes for 3 months, then the
disk failed
◦ Pay subjects incrementally