See Introducing “LinkedIn Salary”: Unlock Your Earning Potential (LinkedIn blog) for more details
"LinkedIn's Economic Graph initiative took another step forward November 2 with the launch of LinkedIn Salary, a new portal that collects and analyzes salaries across jobs globally, which people can then use to better understand the compensation landscape of their given field.
Effectively, the Economic Graph concept is LinkedIn's goal to digitally map the global workforce. This includes creating a profile for every working person, a profile for every company in the world, and a digital representation of every job and every skill set required to obtain those jobs."LinkedIn launches Salary, a tool that taps into user data to chart earnings across the globe | ZDNet