Post on 08-May-2015
Social Network Interventions!
Twitter: @NAChristakis!
Nicholas A. Christakis, MD, PhD!Human Nature Lab!Yale Institute for Network Science!Yale University!
Human Networks Have a Consistent Structure!
Network Interventions
Network Interventions
Observations and Experiments on Social Contagion!
Obesity! Smoking! Drinking! Drug Use!
Happiness! Loneliness! Depression! Altruism!
Sleep! Exercise! Purchases! Ideas!
Network Interventions
Connections Matter!
Network Interventions
GRAPHITE!
Connections Matter!
DIAMOND!
Connections Matter!
source: Brian Uzzi!
Network Interventions
Network Interventions
Connection: changing the structure!!!Contagion: changing the flows !
Intervening in Social Networks!
Network Interventions
Manipulating Connection!ONLINE NETWORK!
D. Centola, “The Spread of Behavior in an Online Social Network Experiment,” Science 2010; 329: 1194-1197!
NEIGHBORHOOD!RANDOM!
Networks & Evolution
D. G. Rand, S. Arbesman, and N.A. Christakis, “Dynamic Social Networks Promote Cooperation in Experiments with Humans,” PNAS 108: 19193-19198 (2011)
Cooperation!and Re-Wiring!
EXPERIMENTS!
Fluid!
Fixed!
Round! 1! 2! 6! 10!
Network Interventions
EXPERIMENT 1: RANDOM PEOPLE!
PEER EFFECTS UNDER CONTROL!
Manipulating Contagion!
Network Interventions
PEER EFFECTS UNDER ACCELERATION!
EXPERIMENT 2: CENTRAL PEOPLE!
Manipulating Contagion!
Network Interventions
Las Marias!HONDURAS!
Network Interventions
Village Networks!HONDURAS!
Network Interventions
Delivering the!Intervention!HONDURAS VILLAGES!
Network Interventions
Mean proportion
of coupons redeemed!
Day!
nominated, 9 villages: 0.8 in-degree, 9 villages: 0.7 random, 7 villages: 0.66
1.0!
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0.8!
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0.6!
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0.4!
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0.2!
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0.0!
0! 2! 4! 6! 8! 10! 12! 14!
VITAMINS IN HONDURAS!
Network Targeting!
Network Interventions
Social Contagion!
VILLAGE EXPERIMENTS!
Network Interventions
Physician!Networks!
SHARED PATIENTS!
2!
1!
1!
1!
Network Interventions
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 !
Physician!Networks!
Physician Networks!
Network Interventions
M. Barnett, N.A. Christakis, A.J. O’Malley, J.P. Onnela, N.L. Keating, and B. Landon, “Physician Patient-Sharing Networks and the Cost and Intensity of Care in US Hospitals,” Medical Care 2012; 50: 152-160!
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 Patient-Sharing Networks and the Cost and Intensity of Care in US Hospitals,” Medical Care 2012; 50: 152-160!
JANUVIA PRESCRIPTIONS!
Network Interventions
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!
Physician!Networks!
Prescribers of Statins, 2009!
Adop%ng Crestor + Generics
Source: www.ActivateNetworks.net!
Prescribers of Statins, 2012!
Source: www.ActivateNetworks.net!
Adop%ng Crestor + Generics
Overall Change in Market Share!
Lipitor
Crestor
Generics
Source: www.ActivateNetworks.net!
Community Differences!
Various colors indicate different communities
Source: www.ActivateNetworks.net!
January 2009 January 2012
Source: www.ActivateNetworks.net!
Influencers Make the Difference
January 2009 January 2012
Source: www.ActivateNetworks.net!
Influencers Make the Difference
Network Interventions
Deliberately Creating Spillovers!!Deliberately Exploiting Peer Reinforcement!
Network Effects!ENHANCING BEHAVIORAL INTERVENTIONS!
Network Interventions
Hospital!Network!
PATIENT TRANSFERS!
Network Interventions
Physician!Networks!
HOSPITAL LEAKAGE!
Edge thickness represents number of patients
Your Hospital
Source: www.ActivateNetworks.net!
Network Interventions
Loyal In The physician shown here is sending patients to your hospital only. These are the physicians to
reward and use as models.
Scattered The highlighted physician is sending patients to multiple different hospitals. This behavior
is likely to be patient-driven.
Loyal Out This physician is sending all of his patients to
one hospital that is not your own. This behavior is likely to be physician-driven.
Physician!Networks!
TYPES OF PHYSICIAN BEHAVIOR!
Source: www.ActivateNetworks.net!
Natural!Network!
Network Interventions
VARIATION IN POSITION!
Network Interventions
CENTRAL PEOPLE!
Network!
Network Interventions
Theoretical Differences in Epidemic Curves!
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NA Christakis and J H Fowler, “Social Network Sensors for Early Detection of Contagious Outbreaks” PLoS One, 5(9): e12948 !
Network Interventions
Observed Differences in Epidemic Curves!
NA Christakis and J H Fowler, “Social Network Sensors for Early Detection of Contagious Outbreaks” PLoS One, 5(9): e12948 !
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DAYS SINCE SEPTEMBER 1 DAYS SINCE SEPTEMBER 1
0 20 40 60 80 100 120
0.00
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02
0.42
0.
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0.08
0.00
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0.00
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0 20 40 60 80 100 120
Network Interventions
PATHOGENS! INFORMATION! NORMS! BEHAVIORS!
Contagious Outbreaks!
Network Interventions
Forecasting Drug Adoption in Physician Networks!
0%
10%
20%
30%
1 3 5 7 9 11 13 15 17 19 21 23 25 27Months
% Ad
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Average Central
Forecasting Capability!
Network Interventions
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!
Computational Social Science!PERVASIVE DATA!
Tyco Brahe (1546-1601)!
Network Interventions
www.ConnectedTheBook.net!
Network Interventions
www.HumanNatureLab.net!
www.NicholasChristakis.net!
www.ActivateNetworks.net!
@NAChristakis!