Voluntary mentorship programs tend to reward those who are already primed for success — eager to learn, engaged, good collaborators.

But what if companies required mentorship for new employees?

The Eccles School’s Nathan Seegert and his colleagues recently studied this question at a call center and found that those who were voluntarily in mentorship programs did not see a huge difference in success levels. But those whose participation was mandatory outperformed their peers by 18%.

Read the in-depth findings in Quartz at Work.