Employers are increasingly using Facebook to screen job applicants and weed out candidates they think have undesirable traits. But a new study from North Carolina State University, in Raleigh, N.C., shows that those companies might have a fundamental misunderstanding of online behavior and, as a result, may be eliminating desirable job candidates.

Researchers tested 175 study participants to measure the personality traits that companies look for in job candidates, including conscientiousness, agreeability, and extraversion. The participants then were surveyed on their Facebook behavior, enabling researchers to see which Facebook behaviors were linked to specific personality traits.

The results likely would surprise many corporate human resources officials, the researchers said.

"Companies often scan a job applicant's Facebook profile to see whether there is evidence of drug or alcohol use, believing that such behavior means the applicant is not 'conscientious,' or responsible and self-disciplined," says Dr. Lori Foster Thompson, a professor of psychology at North Carolina State and co-author of a paper describing the study. However, the researchers found that there is no significant correlation between conscientiousness and an individual's willingness to post content on Facebook about alcohol or drug use.

"This means companies are eliminating some conscientious job applicants based on erroneous assumptions regarding what social media behavior tells us about the applicants," says Will Stoughton, a doctorate student at North Carolina State and lead author of the paper.

Companies that are looking for extroverts, such as those hiring for sales or marketing positions, might be doing themselves an even worse disservice. The study found that extroverts were significantly more likely to post about drugs or alcohol on Facebook.

So companies weeding out those applicants are likely to limit significantly the pool of job candidates who are extroverts.

However, the researchers did find one online indicator strongly correlated to the personality traits that employers look for. Study participants who rated high on both agreeableness and conscientiousness also were unlikely to badmouth or insult other people on Facebook.

"If employers plan to keep using social media to screen job applicants, this study indicates they may want to focus on eliminating candidates who badmouth others—not necessarily those who post about drinking beer," Stoughton says.