@TechReport{iza:izadps:dp3885,
            	author={Cardoso, Ana Rute and Hamermesh, Daniel S. and Varejão, José},
            	title={The Timing of Labor Demand},
            	year={2008},
	month={Dec},
            	institution={Institute of Labor Economics (IZA)},
            	address={Bonn},
            	type={IZA Discussion Paper},
            	number={3885},
            	url={https://www.iza.org/index.php/publications/dp3885},
	abstract={We examine the timing of firms' operations in a formal model of labor demand. Merging a variety of data sets from Portugal from 1995-2004, we describe temporal patterns of firms' demand for labor and estimate production-functions and relative labor-demand equations. The results demonstrate the existence of substitution of employment across times of the day/week and show that legislated penalties for work at irregular hours induce firms to alter their operating schedules. The results suggest a role for such penalties in an unregulated labor market, such as the United States, in which unusually large fractions of work are performed at night and on weekends.},
	keywords={labor demand;time use;wage penalty},
            }