Researchers from New York University studied influence by watching how use of a film-rating app spread through Facebook users. Starting with a seed group of 7,730 users, the researchers designed the app to randomly send messages to the app users' friends, encouraging them to also install the app. Just under 42,000 messages were sent out to a random selection of the initial groups' 1.3 million friends, resulting in nearly 1,000 new app users. This random selection of who gets the message allowed the researchers to avoid common pitfalls in measuring influence, such as homophily bias - the principle that we tend to make friends with people like ourselves.

Analysing the results in combination with users' Facebook profile data revealed a number of insights into which people are the most influential. Men are 49% more influential than women, but women are 12% less susceptible to influence than men, and they exert 46% more influence over men than over other women. Influence also increases with age, with people over 31 being 51% better at convincing their friends than those under 18. Relationship status also plays a role. Single individuals are 113% more influential than those in a relationship and 128% more than those who define their relationship status as 'it's complicated'. On the flip side, susceptibility rises with increasing relationship commitment - up until you get married.