@TechReport{iza:izadps:dp15609,
            	author={Bhalotra, Sonia R. and Clarke, Damian},
            	title={Analysis of Twins},
            	year={2022},
	month={Sep},
            	institution={Institute of Labor Economics (IZA)},
            	address={Bonn},
            	type={IZA Discussion Paper},
            	number={15609},
            	url={https://www.iza.org/index.php/publications/dp15609},
	abstract={The occurrence of twin births has been widely used as a natural experiment. With a focus upon the use of twin births for identification of causal effects in economics, this chapter provides a critical review of methods and results.},
	keywords={child penalty;women's labour market outcomes;birth spacing;fertility;child development;identification;twins},
            }