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Facebook, Twitter and their ilk are digital catnip for hiring managers, but this addiction isn’t a harmless buzz: New research shows that what’s in our profiles has little bearing on how well we do our jobs, even though a large number of recruiters operate under the assumption that it does.

Social media? Everybody’s doing it — everybody in HR, that is. According to one survey by recruiting software company Jobvite, 93% of recruiters surveyed are likely to look at a candidate’s profile in the course of filling a job. More than 40% have reconsidered a job candidate based on what was in a social media profile, and 60% say improper grammar or punctuation, along with four-letter words, make them think poorly of the applicant.

When it comes to profiles and performance, “For some reason, there’s this impetus to think it’s related,” says Philip Roth, professor of management at Clemson University. “Companies are inspecting social profiles to weed out candidates and to get a sense of whether a particular applicant is likely to fit into the culture or not. What you post or Tweet can have positive or negative impact on what recruiters think of you,” Dan Schawbel wrote in TIME last year.

“To me the complications that go with that logic are pretty substantial,” Roth says.

The temptation of using sites like Facebook to take a peek at what job-seekers say and do when they’re off the clock is its accessibility and the sense that it offers a real-life window into someone’s unguarded thoughts. “It’s easy,” Roth says. “The information is just too alluring.”

The trend and the assumption of a correlation between what people display online and what kind of behaviors they display in the workplace also can be ascribed to a misplaced faith in the power of technology to provide better insights than the low-tech methods that preceded it, Roth says.

“People also look at this through a technological lens — technology is good, we’ll try it — but if you look at it as an employment test it ought to have a proven record of predicting job performance,” he says. “If it works you ought to have a track record that it works. The track record for social media isn’t there.”

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In a new Journal of Management article, Roth found that although there’s plenty of information that shows how much social media is used in hiring, there’s a dearth of research on how well it’s being used. Employers are forging ahead and relying on the assumption that a job candidate whose Facebook profile is full of hard-partying photos and devoid of capital letters and commas, for instance, won’t be a good worker.

This assumption is actually dead wrong. In another Journal of Management paper, Roth and lead author Chad Van Iddekinge of Florida State University couldn’t find any link between subjects’ current job performance and what kind of employees recruiters thought these people would be based on evaluations of their Facebook pages. “We had recruiters make predictions and the empirical correlation was essentially zero,” Roth says.

Part of the problem is that there’s really no standard for how to evaluate a Facebook page this way, so HR folks wind up guessing or going with their gut — not a reliable way to assess jobworthiness. Taking what users post on Facebook at face value is a gamble, too — anyone with a Facebook friend who’s prone to embellishing the truth (which is probably most of us) knows that.

There are other reasons why relying on social media as a kind of ad hoc screening tool isn’t a good hiring strategy. “There was evidence of subgroup difference in Facebook ratings that tended to favor female and White applicants,” Van Iddekinge and Roth write.

The authors theorize that the overwhelming amount of personal detail in Facebook profiles “may cause decision makers to rely on biases” as they try to sort out what’s relevant and what isn’t. Roth says using profile content to predict job performance is similar to some employers’ use of credit checks, a practice that’s been banned in some states.

Roth points out that photos and “likes” can give clues to applicants’ race, religion and other classes protected from workplace discrimination. He also says it potentially could skew the playing field either for or against older candidates, who are less likely to be active on social media sites.

Sites like Facebook are a great way for people to put their personality on display, but hiring managers are making a big mistake when they evaluate the profile rather than the person.