The way information and infections spread across complex networks has been the subject of a new study.
A team of researchers led by Dr. Hernan Makse of the City College of New York (CCNY) have said that contrary to conventional wisdom, persons with the most connections are not necessarily the best spreaders.
"The important thing is where someone is located in a network," Nature quoted Makse as saying.
"If someone is in the core, they can spread information more efficiently. The challenge is finding the core," he said.
That kind of information could help marketers and public relations practitioners conduct more effective social media and social marketing campaigns.
It could also help epidemiologists target resources to reduce the spread of infectious diseases.
In the study, the researchers examined four networks representing archetypical examples of social structures: members of LiveJournal.com; email contacts in the computer science department at University College London; inpatients of Swedish hospitals, and adult film actors.
The latter group was studied because it is a distinct subgroup of the acting profession whose members rarely appear in other genres, Makse explained.
Each network member's position in that network was plotted on a graph with the number of connections along one axis and the k-shell value along the other, e.g. (100, 5), (50, 25).
The team found that nodes with many connection hubs located at the periphery of a network, i.e. low k-shell values, were poor spreaders.
However, nodes with fewer connections but locations near the core, i.e. high k-shell values, were just as likely to spread information or infections as similarly situated nodes with more connections. Hence, they conclude the most efficient spreaders are located in a network's inner core.
"In the case of LiveJournal, someone with a thousand friends but a low k-shell level will have less impact than someone with a hundred friends but a high k-shell level.
"Small players and big players spread just as well if they are at the core of the network," Makse said.
For the spread of disease, nodes located in high k-shell layers are more likely to be infected and they will be infected sooner than other nodes, the researchers found.
"The neighborhood of these nodes makes them more efficient in sustaining an infection in early stages, thus enabling the epidemic to reach a critical mass such that it can fully develop," he said.
The findings appeared in Nature Physics.