1. A 61-million-person experiment in
social influence and political
mobilization
Robert M. Bond, Christopher J. Fariss, Janson J.
Jones, Jaime E. Settle and James H. Fowler
UCSD
Adam D. I. Kramer and Cameron Marlow
Facebook

2. Outline
• Main Results
• Technical Details

3. Main Results
• A randomized controlled trial
• > 18 years old, U.S.
• Nov. 2nd, 2010 – U.S. congressional election.

4. Main Results
• Three groups of users
▫ “social message”
 n = 60,055,176 (99%)
▫ “informational”
 n = 611,096 (1%)
▫ “no message”
 n = 611,044 (1%)

5. Main Results

6. Main Results polling places

7. Main Results self-reported voting

8. Main Results social message

9. Main Results

10. Main Results

11. Main Results 20.04% vs. 17.96%

12. Main Results
• Self-expression + information seeking

13. Main Results
• Self-expression + information seeking
No guarantee!

14. Main Results
• Self-expression + information seeking
No guarantee!
• Match with public voting records

15. Main Results
• social message vs. no message: 0.39%

16. Main Results
• social message vs. informational message: 0.39%

17. Main Results
• informational message vs. no message: 0.00%

18. Main Results

19. Main Results
• 149 friends on average
• Strong ties behavioral effect?

20. Main Results
• Divide types of interactions by decile
• High-level interactions mean close friends?

21. Main Results

22. Main Results
• Compare
Social message No message

23. Main Results

24. Main Results

25. Main Results

26. Main Results

27. Main Results

28. Main Results
• Close friends matter.

29. Main Results
• Something real?

30. Main Results
• Something real?
▫ friends: 886,000 expressed votes
▫ close friends: + 559,000 expressed votes
▫ close friends of close friends: + 1M expressed votes

31. Main Results
• Something real?
friends:
▫ 282,000 validated votes
▫ 74,000 polling-place searches

32. Main Results
• Some context
▫ US midterm elections
 36.3% (2002) to 37.2%
(2006) To 37.8% (2010)
▫ 60,000 voters (d)
▫ 280,000 voters (i)
▫ 0.14% of 236M in 2010

33. Main Results
• Claims
▫ Online political mobilization works.
▫ Generate real validate votes.
 Contradict previous research.
▫ Social mobilization is significantly effective than
informational mobilization alone.
▫ Close friends have about four times more influence.
▫ Online social networks influence offline behaviors.

34. Technical Details

35. Technical Details

36. Technical Details

37. Technical Details

38. Technical Details
• Matching to Voting Records
▫ First names + last Names + full birthdates
▫ Cost $0 -> $1500 per state
▫ Exclude Texas
▫ Include
 Arkansas, California, Connecticut, Florida, Kansas,
Kentucky, Missouri, Nevada, New Jersey, New
York, Oklahoma, Pennsylvania and Rhode Island
▫ 40% of all registered votes -> 6,338,882 voters
and abstainers.

39. Technical Details
• Matching to Voting Records (cont.)
▫ 1/3 matched.
▫ Name conventions.

40. Technical Details
• Overreporting and Underreporting
▫ 3.8% self-reported -> abstained
▫ 50.1% declined to report -> voted
• Social message vs. informational message
▫ 0.99% more likely to overreport to voting
▫ 4.19% less likely to underreport voting

41. Technical Details
• Determination of “Close” Friends
▫ Media multiplexity
▫ # interactions of f/ total # of interactions with all
▫ Divide by decile.
▫ Each decile is a subset of the previous one.
▫ Validated via survey.

42. Technical Details
• Network permutation
▫ Keep the network topology fixed
▫ Randomly permute the assignment to treatment
▫ Repeat 1,000 times
▫ Theoretical null distribution