‘Moderately weak’ ties best for moving jobs, study finds

Whether it’s the friend of a friend or a new contact from a conference, arms-length acquaintances have long been thought more useful than close chums when it comes to switching jobs.

Now researchers say they have finally found a way to test the theory, revealing that while such “weak ties” do seem to facilitate job shifts, the most useful share a handful of mutual contacts.

Weak ties are thought to be beneficial for everything from employment opportunities to innovation because they provide a bridge between clusters of people who know each other, allowing new information and ideas to flow.

“If you are the one in your cluster that has the weak tie bridges to other clusters, you see novel information first, so you have an opportunity to act on that before other people,” said Prof Sinan Aral, of the Massachusetts Institute of Technology, who is a co-author of the research. He said one example was the chance of a new job.

“We know that weak ties and job mobility are correlated. But we didn’t really know whether weak ties were causing the job mobility,” he said.

Writing in the journal Science, Aral and colleagues report how they carried out two experiments, one involving more than 4 million LinkedIn members in 2015 and one involving more than 16 million members in 2019.

In both, the team tweaked the algorithms behind a tool called “People You May Know” to ensure members were randomly recommended connections with either people who had few mutual contacts, known as weak ties, or people who many contacts in common with them, known as strong ties.

Once a member had accepted a recommendation, the team tracked how many messages were sent between the pair. They also looked at whether members applied for or moved jobs.

The team found that the probability of a LinkedIn member joining the same company as their new contact was higher when the number of contacts they shared was higher. However, once this number exceeded 10 mutual contacts, the probability fell.

“The best ties for job mobility aren’t the weakest ties, they are moderately weak,” said Aral.

The team also found that members who rarely exchanged messages with their new contact, and hence could also be deemed a weak tie, had a greater chance of joining the same firm.

Aral said this might be because such conversations are concentrated, rather than embracing everyday life. “They’re focused on a few practical topics like how suitable are you for a job in my company,” he said.

In another twist, the team found that in general, increasing the number of weak ties boosted the number of job applications members made. But further analysis showed such ties were of greater importance in more digitally focused industries, whereas strong ties led to more job applications in industries that rely less on software skills.

Aral said that as well as examining the importance of weak ties, the study highlighted the degree to which social media algorithms “are turning the knobs on our economies and fundamental indicators like employment”.

Dr Bernie Hogan, a senior research fellow at the Oxford Internet Institute, who was not involved in the work, said the research offered robust evidence for the strength of weak ties, but also showed that not all such connections are helpful.

“You really need to be in that sweet spot of [connecting with] someone who knows people you know, but doesn’t know the same things as everyone you know,” he said.

Hogan added that the findings also point to practical tips for those seeking new employment. “It’s easy to think about asking your immediate colleague or your best friend for job advice,” he said. “But clearly that’s not what we ought to be doing. We ought to be looking a little further afield.”