If you’ve ever felt like your friends have more active social lives than you, you’re not imagining it. In fact, research shows you’re probably right. Social scientists have long recognized the “friendship paradox,” which states that, on average, your friends likely have more friends than you do.

While this might not be great for your self-esteem, it’s excellent for spreading information efficiently—whether that’s a vaccine campaign, raising awareness about a product, or curbing misinformation.

New research from Yale looks at how to identify the most well-connected individuals in a social network without needing a map of the entire network. The study builds on the friendship paradox to present two methods for targeting interventions in online and real-world networks, which could prove valuable in fields like public health, marketing, and politics.

Birds of a feather

The research explores “inversity,” which measures how similar or different two connected individuals are in terms of how many friends they have. This plays a key role in identifying the most connected people.

One approach, the “ego-based strategy,” involves asking a random person in a network to identify one of their friends. That friend then becomes the “seed” for the intervention—whether it’s receiving a vaccine or sharing information. This method has been used before, but this study is the first to prove its effectiveness mathematically and empirically.

The second, newer approach is called the “alter-based strategy.” In this method, a random person in the network is asked to provide contact information for multiple friends based on a set percentage, such as flipping a coin to decide whether to share each friend’s details. The selected friends are then targeted for the intervention.

Strong results

Both strategies outperform traditional methods, such as choosing random people or network leaders to seed interventions. For example, in a disease outbreak, immunizing just 25% of a network using these methods could stop an epidemic, whereas random targeting would require vaccinating around 50%.

A key advantage of these approaches is that they respect privacy. Unlike other methods, they don’t require detailed information about the entire network to be effective.

The study’s findings have wide-ranging implications. In addition to public health campaigns, these strategies could be used in marketing to spread word of a new product or even to track how misinformation about a candidate is circulating in a political network.

In any of these cases, the friendship paradox offers a powerful tool for reaching the most influential people in a network quickly and efficiently.