Braakmann, Nils; Wildman, John - Volkswirtschaftliche Fakultät, … - 2014
Twin births are often used as an instrument for fertility in models investigating the impact of family size on labour … market and child outcomes. However, a large share of twin births (24% in our sample) are the result of fertility treatments … show that (a) mothers with and without fertility treatment are different, (b) twin births are still random after …