"Employees who do not belong to any social networks leave their jobs more rapidly than those who belong to four or fewer. On the opposite end of the spectrum, employees who belong to five or more social networks also leave their jobs more rapidly than those in the middle group. Employees who belong to four or fewer social networks tend to stay put the longest." http://www.inc.com/francesca-fenzi/social-media-not-the-productivity-killer-you-thought.html