Efficiency Wages

The New York Times has a story about several restaurants that have decided to pay above-market wages.  One of them is Shake Shack, which is starting employees at $9.50/hr:

“The No. 1 reason we pay our team well above the minimum wage is because we believe that if we take care of the team, they will take care of our customers,” said Randy Garutti, the chief executive of Shake Shack.

That, and other anecdotes in the article, are consistent with the "efficiency wage" theory, where firms can induce more effort by paying a higher real wage.  This might arise if firms have a less than perfect ability to monitor individual employees' productivity - paying an above-market wage creates a stronger incentive not to "shirk". 

For more, see this brief 1984 survey by Janet Yellen, who did some of her early academic work in this area.