A simple suggestion for recruiters and hiring managers: State in your job listing that you will not contact references who did not serve as a manager for a candidate.

In other words, no references from coworkers and peers at their previous companies.

That sounds like a hard line, perhaps, and there is probably some wiggle room. Obviously, if one of your employees is referring the candidate as a former coworker, that might be more valuable than any reference check. And yes, let's acknowledge up front, some employees just don't mingle with some managers, and sometimes that's the managers' fault. Or they might not want their manager to know they're looking for a new gig. So perhaps the candidate doesn't want to list a manager with good reason.

But you should force an explanation like this, because by and large you're going to get a lot more out of a reference check with a manager compared to a peer, suggests Allison Green on her Ask A Manager blog. Here's why.

1. Managers assess performance. Managers, as opposed to peers, exist to determine just how well an employee is doing in their role, Green writes. Coworkers might be able to speak to a candidate's attitude and skills, but they're less likely to have a full understanding of how well the employee fulfills his or her duties and responsibilities. There are also conversations managers have with employees that lend insight coworkers generally can't get. Examples, Green writes, include how the candidate handles feedback or the sorts of ideas they've helped cook up from a strategic standpoint.

2. Managers have a bird's eye view. Along similar lines, even if coworkers can speak to how well an employee completes the tasks given to them and fulfills organizational and personal goals, their point-of-view is flat. Managers have a much better sense for how the candidate fits into their team and organization at large, rather than into one individual employees' day-to-day.

3. Managers aren't cherry-picked. In most situations, employees have far more peers than they do supervisors. So giving them the opportunity to choose a peer opens the door far wider for a biased review than their finite number of managers--especially if the candidate and their worker are friends. 

As to the third point, it's worth acknowledging the obvious: An employee isn't going to put anybody--manager or not--on their list of references if they don't expect a good one. So it's important to know how to draw honest responses out of references in the first place. To that end check out this article, which presents three steps for making the reference check more than a rubber stamp. Central to all of them: Find creative ways to get references to give real feedback about a candidate without jeopardizing their relationship or, for that matter, their internal HR policies.