Conventional wisdom suggests that bigger is better, particularly when it comes to online social networks. But for those who are unemployed and want to use their professional contacts to open doors with hiring managers, having a large network made up of irrelevant (or weak) connections won’t help secure an interview or job offer.

They say it’s not what you know, it’s who you know. If that’s true, being connected to as many people as possible is surely the best way to build a strong online social network of professional peers and colleagues. After all, each of us — at some time or another — will need to tap into that network to find a new job or change careers. Having a large number of contacts on LinkedIn seems like a good way to amass valuable resources who can offer job leads and recommendations when needed.

But research from Texas McCombs Assistant Professor Rajiv Garg says it doesn’t, and that having a network that’s too big or composed mostly of people you don’t know well can actually backfire right when you need it most.

Together with Carnegie Mellon co-author Rahul Telang, Garg followed 109 unemployed LinkedIn users to see how easily they searched for jobs, got interviews, and secured job offers. Of the LinkedIn users they tracked for two months, those who had mostly weak ties had more job leads, but those with stronger connections got more interviews and job offers.

Garg refers to a “strong tie” as someone you know well and communicate with periodically, while a “weak tie” is someone you have a loose connection with — for example, a friend of a friend or a person you met at a conference but haven’t spoken with since.

Most social networks, by their nature, include both weak and strong ties. Past research, including Michael Granovetter’s influential 1973 paper “The Strength of Weak Ties,” has shown that weak ties can be useful because they tend to provide more job leads than strong ties can. This is because, unlike strong ties, you don’t hear from weak ties often, so when you do reach out to them, they tend to have more new information about job openings that you weren’t already tapped into.

Strong Ties Lead to Interviews and Job Offers

“Weak ties help job-seekers find new leads, but they can’t help with recommendations — and recommendations matter more,” says Garg. “Having a lot of connections on LinkedIn is great so long as you’re able to maintain a stronger relationship with them. That stronger relationship allows you to get better interviews, more interviews, and more offers.”

But while weak ties are better at providing job leads, having too many of those loose connections can work against you.

Frequent communication is key to maintaining strong ties, but when you have a very large online social network, it can be difficult (if not impossible) to sustain those relationships. And while there is not an exact number of contacts to aim for, Garg notes that the Dunbar Number — the number of meaningful relationships we can sustain — is 150.

That distance makes it harder for a contact to offer you the recommendation that gets you the interview or the job offer.

Additionally, to a recruiter or hiring manager, an applicant’s large professional network can appear impressive at first glance. But if the job-seeker and employer have a contact in common, a network can become suspect very quickly.

“The recruiter might choose to contact that person and ask for a recommendation. If the person says, ‘Yes, and she’s great,’ that’s awesome. You will get the interview. If the person says, ‘No, I don’t know her much. I just got connected on LinkedIn,’ you’ve basically lost the opportunity. If there were no shared connection at all, you probably would have done better. So having a larger number of weaker connections actually hurts you from the interviews and offers perspective,” says Garg.

Make It Personal

Garg’s advice for job-seekers?

“Know people,” he says. Attend relevant conferences, workshops, and meetings. “Don’t tell the recruiters you’re looking for a job, but [rather] amaze people with your talent and skill set and then connect with them on LinkedIn or other social networks.”

Most important, follow up. Turn the weak tie into a strong tie by sending a note, keeping in touch, and meeting again for coffee or lunch when possible. By impressing someone who can advocate on your behalf, you have the strongest possible connection to a potential new job.

If a weak tie can offer you a job lead but not a recommendation, try to find a stronger tie who can. Known as the “spillover effect,” this is the research you do to find connections to people and organizations that aren’t immediately obvious — such as a valued colleague who turns out to be good friends with a hiring manager you’d like to meet.

And when you get that request to connect on LinkedIn from someone you’ve never met? Ignore it.

“Connecting online without any interaction beforehand or any referral point of contact is useless,” says Garg.