Using data from nearly 2 million people and 8 million phone calls over the course of a year, physicist Cesar Hidalgo from the University of Notre Dame and sociologist Carlos Rodriguez-Sickert from the Pontifical Catholic University of Chile have investigated the persistence of relationships within the cell phone network. Somewhat intuitively, they found that the leading cause of persistent relationships is reciprocity - returning a friend´s call. Further, they could use these characteristics to predict the nature of relationships in the future.
As the researchers explain in their study, the persistence of the connection between two individuals is a measurement of how often they call each other. The scientists analyzed 15-day intervals, and determined if the two callers made contact within each interval. The greater number of these chunks of time in which contact occurred, the higher the pair´s persistence value was.
The scientists found that the majority (60%) of ties between two callers lasted for just one 15-day interval. The next 20% of ties disappeared slowly throughout the course of the year, and the remaining 20% persisted for the entire one-year period.
The results showed that the strongest factor determining persistence values was when individuals returned calls to each other. When links were reciprocated, those links had a greater chance of persisting for longer time periods. Also, when an individual´s connections had connections among themselves (when a person´s friends knew each other), his or her own connections lasted longer.
Above: A network model created with data from the study: blue nodes are males, pink nodes are females, and gray nodes are unknown gender. The node size is proportional to the age of the phone user, and the color and width of the links grows with persistence. Image credit: Cesar Hidalgo and Carlos Rodriguez-Sickert.
PhysOrg.com via Dosh Dosh
