Social Network Interventions!
Nicholas A. Christakis, MD, PhD!
Human Nature Lab!
Yale Institute for Network Science!
Yale ...
Network Interventions

Human Networks Have a Consistent Structure!
Network Interventions

Observations and Experiments on Social Contagion!
Obesity!

Smoking!

Drinking!

Drug Use!

Happine...
Network Interventions

Connections Matter!
Network Interventions

Connections Matter!

GRAPHITE!

DIAMOND!
Network Interventions

Connections Matter!

source: Brian Uzzi!
Network Interventions

Intervening in Social Networks!

Connection: changing the structure!
!
!
Contagion: changing the flo...
Network Interventions

Manipulating Connection!
ONLINE NETWORK!

RANDOM!

NEIGHBORHOOD!
D. Centola, “The Spread of Behavio...
Networks & Evolution

Cooperation!
and Re-Wiring!
EXPERIMENTS!
Fluid!

Fixed!

Round!

1!

2!

6!

10!

D. G. Rand, S. Arb...
Network Interventions

Manipulating Contagion!
EXPERIMENT 1: RANDOM PEOPLE!

PEER EFFECTS UNDER CONTROL!
Network Interventions

Manipulating Contagion!
EXPERIMENT 2: CENTRAL PEOPLE!

PEER EFFECTS UNDER ACCELERATION!
Network Interventions

Las Marias!
HONDURAS!
Network Interventions

Village Networks!
HONDURAS!
Network Interventions

Delivering the!
Intervention!
HONDURAS VILLAGES!
Network Interventions

Network Targeting!
VITAMINS IN HONDURAS!

1.0!
!
0.8!

Mean
proportion

of coupons
redeemed!

!
0.6...
Network Interventions

Social
Contagion!
VILLAGE EXPERIMENTS!
Network Interventions

Physician!
Networks!
SHARED PATIENTS!

2!
1!

1!

1!
Network Interventions

Physician!
Networks!
BOSTON HOSPITALS!

B.E. Landon, N.L. Keating, M.L. Barnett, J.P. Onnela, S. Pa...
Network Interventions

Physician Networks!

M. Barnett, N.A. Christakis, A.J. O’Malley, J.P. Onnela, N.L. Keating, and B. ...
Network Interventions

Physician!
Networks!
HOSPITAL SPENDING!

M. Barnett, N.A. Christakis, A.J. O’Malley, J.P. Onnela, N...
Network Interventions

Physician!
Networks!
JANUVIA PRESCRIPTIONS!

40 – 57 shared patients!
58 – 106 shared patients!
107...
Prescribers of Statins, 2009
!

Adop%ng	
  	
  
Crestor	
  +	
  Generics	
  

Source: www.ActivateNetworks.net!
Prescribers of Statins, 2012
!

Adop%ng	
  	
  
Crestor	
  +	
  Generics	
  

Source: www.ActivateNetworks.net!
Overall Change in Market Share
!

Lipitor	
  
Crestor	
  
Generics	
  

Source: www.ActivateNetworks.net!
Community Differences
!

Various colors indicate
different communities

Source: www.ActivateNetworks.net!
Influencers Make the Difference
	
  
January	
  2009	
  

January	
  2012	
  

Source: www.ActivateNetworks.net!
Influencers Make the Difference
	
  
January	
  2009	
  

January	
  2012	
  

Source: www.ActivateNetworks.net!
Network Interventions

Network Effects!
ENHANCING BEHAVIORAL INTERVENTIONS!

Deliberately Creating Spillovers!
!
Deliberat...
Network Interventions

Hospital!
Network!
PATIENT TRANSFERS!
Network Interventions

Your Hospital

Physician!
Networks!
HOSPITAL LEAKAGE!

Edge thickness
represents
number of patients...
Network Interventions

Physician!
Networks!
TYPES OF PHYSICIAN BEHAVIOR!

Loyal In

Scattered

Loyal Out

The physician sh...
Network Interventions

Natural!
Network!
VARIATION IN POSITION!
Network Interventions

Network!
CENTRAL PEOPLE!
Network Interventions

DAILY INCIDENCE
OF CONTAGION

CUMULATIVE INCIDENCE
OF CONTAGION

Theoretical Differences in Epidemi...
Network Interventions

0.0004
0.0000

DAILY INCIDENCE
OF INFLUENZA

0.0012
0.0008

0.06
0.42
0.02
0.00

CUMULATIVE INCIDEN...
Network Interventions

Contagious Outbreaks!

PATHOGENS!

INFORMATION!

NORMS!

BEHAVIORS!
Network Interventions

Forecasting Drug Adoption in Physician Networks!
Average

% Adoption

30%

Central

20%

10%
Foreca...
Network Interventions

Computational Social Science!
PERVASIVE DATA!

Internet (social networks, websites, links, etc.)!
T...
Network Interventions

Tyco Brahe (1546-1601)!
Network Interventions

www.NicholasChristakis.net!
www.ConnectedTheBook.net!
www.HumanNatureLab.net!
www.ActivateNetworks....
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CISummit 2013: Nicholas Christakis, Using Social Networks and Social Influence to Affect the Behavior of Physcians

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CISummit 2013: Nicholas Christakis, Using Social Networks and Social Influence to Affect the Behavior of Physcians

  1. 1. Social Network Interventions! Nicholas A. Christakis, MD, PhD! Human Nature Lab! Yale Institute for Network Science! Yale University! Twitter: @NAChristakis!
  2. 2. Network Interventions Human Networks Have a Consistent Structure!
  3. 3. Network Interventions Observations and Experiments on Social Contagion! Obesity! Smoking! Drinking! Drug Use! Happiness! Loneliness! Depression! Altruism! Sleep! Exercise! Purchases! Ideas!
  4. 4. Network Interventions Connections Matter!
  5. 5. Network Interventions Connections Matter! GRAPHITE! DIAMOND!
  6. 6. Network Interventions Connections Matter! source: Brian Uzzi!
  7. 7. Network Interventions Intervening in Social Networks! Connection: changing the structure! ! ! Contagion: changing the flows !
  8. 8. Network Interventions Manipulating Connection! ONLINE NETWORK! RANDOM! NEIGHBORHOOD! D. Centola, “The Spread of Behavior in an Online Social Network Experiment,” Science 2010; 329: 1194-1197!
  9. 9. Networks & Evolution Cooperation! and Re-Wiring! EXPERIMENTS! Fluid! Fixed! Round! 1! 2! 6! 10! D. G. Rand, S. Arbesman, and N.A. Christakis, “Dynamic Social Networks Promote Cooperation in Experiments with Humans,” PNAS 108: 19193-19198 (2011)
  10. 10. Network Interventions Manipulating Contagion! EXPERIMENT 1: RANDOM PEOPLE! PEER EFFECTS UNDER CONTROL!
  11. 11. Network Interventions Manipulating Contagion! EXPERIMENT 2: CENTRAL PEOPLE! PEER EFFECTS UNDER ACCELERATION!
  12. 12. Network Interventions Las Marias! HONDURAS!
  13. 13. Network Interventions Village Networks! HONDURAS!
  14. 14. Network Interventions Delivering the! Intervention! HONDURAS VILLAGES!
  15. 15. Network Interventions Network Targeting! VITAMINS IN HONDURAS! 1.0! ! 0.8! Mean proportion
 of coupons redeemed! ! 0.6! ! 0.4! nominated, 9 villages: 0.8 in-degree, 9 villages: 0.7 random, 7 villages: 0.66 ! 0.2! ! 0.0! 0! 2! 4! 6! 8! Day! 10! 12! 14!
  16. 16. Network Interventions Social Contagion! VILLAGE EXPERIMENTS!
  17. 17. Network Interventions Physician! Networks! SHARED PATIENTS! 2! 1! 1! 1!
  18. 18. Network Interventions Physician! Networks! BOSTON HOSPITALS! B.E. Landon, N.L. Keating, M.L. Barnett, J.P. Onnela, S. Paul, A.J. O’Malley, T. Keegan, and N.A. Christakis, “Variation in Patient-Sharing Networks of Physicians Across the United States,” JAMA 2012; 308: 265-273 !
  19. 19. Network Interventions Physician Networks! M. Barnett, N.A. Christakis, A.J. O’Malley, J.P. Onnela, N.L. Keating, and B. Landon, “Physician PatientSharing Networks and the Cost and Intensity of Care in US Hospitals,” Medical Care 2012; 50: 152-160!
  20. 20. Network Interventions Physician! Networks! HOSPITAL SPENDING! M. Barnett, N.A. Christakis, A.J. O’Malley, J.P. Onnela, N.L. Keating, and B. Landon, “Physician PatientSharing Networks and the Cost and Intensity of Care in US Hospitals,” Medical Care 2012; 50: 152-160!
  21. 21. Network Interventions Physician! Networks! JANUVIA PRESCRIPTIONS! 40 – 57 shared patients! 58 – 106 shared patients! 107+ shared patients! ! did not use Januvia! used Januvia! ! 0 – 57 prescriptions! 58 – 328 prescriptions! 329+ prescriptions! Source: www.ActivateNetworks.net!
  22. 22. Prescribers of Statins, 2009 ! Adop%ng     Crestor  +  Generics   Source: www.ActivateNetworks.net!
  23. 23. Prescribers of Statins, 2012 ! Adop%ng     Crestor  +  Generics   Source: www.ActivateNetworks.net!
  24. 24. Overall Change in Market Share ! Lipitor   Crestor   Generics   Source: www.ActivateNetworks.net!
  25. 25. Community Differences ! Various colors indicate different communities Source: www.ActivateNetworks.net!
  26. 26. Influencers Make the Difference   January  2009   January  2012   Source: www.ActivateNetworks.net!
  27. 27. Influencers Make the Difference   January  2009   January  2012   Source: www.ActivateNetworks.net!
  28. 28. Network Interventions Network Effects! ENHANCING BEHAVIORAL INTERVENTIONS! Deliberately Creating Spillovers! ! Deliberately Exploiting Peer Reinforcement!
  29. 29. Network Interventions Hospital! Network! PATIENT TRANSFERS!
  30. 30. Network Interventions Your Hospital Physician! Networks! HOSPITAL LEAKAGE! Edge thickness represents number of patients Source: www.ActivateNetworks.net!
  31. 31. Network Interventions Physician! Networks! TYPES OF PHYSICIAN BEHAVIOR! Loyal In Scattered Loyal Out The physician shown here is sending patients to your hospital only. These are the physicians to reward and use as models. The highlighted physician is sending patients to multiple different hospitals. This behavior is likely to be patient-driven. This physician is sending all of his patients to one hospital that is not your own. This behavior is likely to be physician-driven. Source: www.ActivateNetworks.net!
  32. 32. Network Interventions Natural! Network! VARIATION IN POSITION!
  33. 33. Network Interventions Network! CENTRAL PEOPLE!
  34. 34. Network Interventions DAILY INCIDENCE OF CONTAGION CUMULATIVE INCIDENCE OF CONTAGION Theoretical Differences in Epidemic Curves! TIME TIME NA Christakis and J H Fowler, “Social Network Sensors for Early Detection of Contagious Outbreaks” PLoS One, 5(9): e12948 !
  35. 35. Network Interventions 0.0004 0.0000 DAILY INCIDENCE OF INFLUENZA 0.0012 0.0008 0.06 0.42 0.02 0.00 CUMULATIVE INCIDENCE OF INFLUENZA 0.08 Observed Differences in Epidemic Curves! 0 20 40 60 80 100 DAYS SINCE SEPTEMBER 1 120 0 20 40 60 80 100 120 DAYS SINCE SEPTEMBER 1 NA Christakis and J H Fowler, “Social Network Sensors for Early Detection of Contagious Outbreaks” PLoS One, 5(9): e12948 !
  36. 36. Network Interventions Contagious Outbreaks! PATHOGENS! INFORMATION! NORMS! BEHAVIORS!
  37. 37. Network Interventions Forecasting Drug Adoption in Physician Networks! Average % Adoption 30% Central 20% 10% Forecasting Capability! 0% 1 3 5 7 9 11 13 15 Months 17 19 21 23 25 27
  38. 38. Network Interventions Computational Social Science! PERVASIVE DATA! Internet (social networks, websites, links, etc.)! Telephony! Video cameras in cities! RFID devices! Administrative records (e.g., physician visits, crimes)! Transaction records! Geographic information! Voluntary losses of anonymity (data wikis)! Personal genetics!
  39. 39. Network Interventions Tyco Brahe (1546-1601)!
  40. 40. Network Interventions www.NicholasChristakis.net! www.ConnectedTheBook.net! www.HumanNatureLab.net! www.ActivateNetworks.net! @NAChristakis!

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