How Social Networks Can Save Lives When Disaster Strikes
https://phys.org/news/2018-09-social-networks-disasters.html
Noting the vulnerability of many communities to natural disasters social scientists have set out to study human behavior during these crises to improve warning systems and lower casualty rates. The researchers suspected that social capital might be a critical factor, so they decided to use social media as a tool to study people’s social networks and whether it impacted evacuation behavior. The social scientists worked alongside researchers from Facebook using high-level, aggregated and anonymized summaries of city-level data before, during and after a disaster to construct the outcome variables “Did you evacuate?” and “If you did, how soon after the disaster did you return?” They looked at three different types of social ties in each person’s social network:
- Bonding ties, which connect people to close family and friends
- Bridging ties, which connect them through a shared interest, workplace or place of worship
- Linking ties, which connect them to people in positions of power.
The research indicated that, controlling for a number of other factors, individuals with more connections beyond their immediate families and close friends were more likely to evacuate from vulnerable areas in the days leading up to a hurricane. Reasons include: (1) people with more bridging ties have far-reaching social networks, connecting them to sources of support outside of areas directly affected by distasters; (2) people with more bridging ties may have built those networks by moving or traveling more, and thus feel more comfortable evacuating far from home during a disaster.
The data also showed that users with linking ties, i.e., they were following politicians and political figures were more likely to evacuate. This may be because they were more likely to receive warning information and trust authority figures disseminating that information. The most important and surprising finding was that having stronger bonding ties – that is, family and friends – made people less likely to evacuate leading up to a hurricane. People whose immediate, close networks are strong may feel supported and better-prepared to overcome the disaster.
The article alludes to many graph theory concepts. The researchers definition of bonding ties is similar to the concept of weak and strong ties. The idea of a bridging tie is what we know as a local bridge. It is fascinating how graph theory and social media sites can help social scientists make better sense of people’s behavior and how we can best interpret the result to improve warning systems.