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When it comes to multiple interviews for a prospective new hire, is it a case of “too many cooks spoil the broth” or “two heads are better than one”? Does an additional interviewer or two (or three) provide valuable insight or just muddy the waters?

If you’ve ever wondered if putting job candidates in front of a wide range of interviewers was essential or just exhausting, a new post on Google’s re:Work blog is required reading. It lays out the latest research on the subject and comes to a straightforward conclusion: “With more people, you are more likely to correctly identify the best person. Or, put another way, with more people you’re less likely to accidentally pass over your best candidate.”

Science Says This Is the Ideal Number of Interviewers

The post was written by Kate Glazebrook, a principal advisor at the Behavioural Insights Team, a British company which aims to apply behavioral science to social problems. It describes how the team recruited teams of people through Mechanical Turk to evaluate job candidate’s answers to behavioral questions like, “Tell me about a time when you used your initiative to resolve a difficult situation?” based on guidelines for what constituted a great response.

The team’s first, most obvious finding was that crowds really are wise. If you get hundreds of evaluators to weigh in they almost always chose the best person for the job. But few companies are sadistic/masochistic enough to subject candidates to tens—more or less hundreds—of interviews. What did the results say about more a doable number of interviews?

In short, an extra opinion or two can be hugely valuable. Even in “easy” cases where the best choice should have been fairly obvious, a single interviewer hired the wrong candidate 16% of the time. Make that three interviewers, and the wrong person gets selected in just 6% of cases. If it’s five people reviewing an application, it’s down to a miniscule 1% error rate.

And how about the hard cases where candidates are quite similar? Then apparently, hearing from multiple voices is ever more important. Just one interviewer made the right choice only about half the time (49%). Three interviewers, on the other hand, got it right around three-out-of four times (72%).

The bottom line? “We recommend getting at least three reviewers to vet each candidate. This can significantly improve the odds of making the best hire,” writes Glazebrook.

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