Employment trends ofyoung mothers and the opportunity cost of babies in the United States
Employment trends ofyoung mothers and the opportunity cost of babies in the United States
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美国年轻母亲的就业趋势与婴儿的机会成本
作者：
J. Cramer
生育的微观经济理论的中心概念是机会成本，即由于生育而失去的妻子的就业和她的就业价值的产物。本文提出了一个利用面板数据分析机会成本的模型。第二胎或更高胎出生造成的就业损失，按2岁左右计算，平均每年超过400小时。这一时间成本意味着以1969年美元计算的收入损失约为1050美元。时间成本不受出生顺序和最年长兄弟姐妹年龄等人口统计学因素的影响。时间成本也不取决于丈夫的工资率或妻子的教育程度或潜在工资率。这表明，许多生育率的微观经济模型被严重错误地指定。本文还比较了静态模型和动态模型的结果，探讨了由于时间性偏差而可能出现的问题，研究了就业变化（包括时间成本）与初始就业水平之间的关系，并指出了机会成本理论化的困难。
The central concept of microeconomic theories of fertility is opportunity cost—the product of wife’s employment lost due to childbearing and the value of her employment. This paper presents a model for analyzing opportunity cost using panel data. The average loss of employment attributable to a second- or higher-order birth, calculated at around age 2, is over 400 hours per year. This time cost represents an income loss of about $1050 in 1969 dollars. Time cost is independent of such demographic factors as birth order and age of oldest sibling. Neither does time cost depend on husband’s wage rate or wife’s education or potential wage rate. This indicates that many microeconomic models of fertility have been seriously misspecified. The paper also compares results from static and dynamic models, explores possible problems due to simultaneity bias, investigates the relationship between changes in employment (including time cost) and initial employment level, and identifies the difficulties of theorizing about opportunity cost.