Using application data from Careerbuilder.com, researchers created a differentiated jobs model and find direct evidence of substantial job differentiation. Researchers find evidence of significant monopsony power: their model finds that workers may produce 21% more than their wage level.
Abstract and Citation
Azar, José and Berry, Steven T. and Marinescu, Ioana Elena, Estimating Labor Market Power (September 18, 2019). Available at SSRN: https://ssrn.com/abstract=3456277 or http://dx.doi.org/10.2139/ssrn.3456277