Department of Policy Analysis and Management, Cornell University, Ithaca, NY 14853, USA.
J Health Econ. 2013 Jul;32(4):743-55. doi: 10.1016/j.jhealeco.2013.04.006. Epub 2013 May 9.
In response to the dramatic rise in childhood obesity, the Centers for Disease Control (CDC) and other organizations have advocated increasing the amount of time that elementary school children spend in physical education (PE) classes. However, little is known about the effect of PE on child weight. This paper measures that effect by instrumenting for child PE time with the state's mandated minimum number of minutes of PE, using data from the Early Childhood Longitudinal Study, Kindergarten Cohort (ECLS-K) for 1998-2004. Results from IV models indicate that PE lowers BMI z-score and reduces the probability of obesity among 5th graders. This effect is concentrated among boys; we find evidence that this gender difference is partly attributable to PE being a complement with other physical activity for boys, whereas they are substitutes for girls. This represents some of the first evidence of a causal effect of PE on youth obesity, and thus offers at least some support for the assumptions behind the CDC recommendations. We find no evidence that increased PE time crowds out time in academic courses or has spillovers to achievement test scores.
针对儿童肥胖率的急剧上升，疾病控制与预防中心（CDC）和其他组织提倡增加小学生上体育课的时间。然而，人们对体育课对儿童体重的影响知之甚少。本文通过使用儿童体育课时间的州规定的最低分钟数作为工具变量来衡量这种影响，使用了 1998-2004 年幼儿纵向研究幼儿园队列（ECLS-K）的数据。IV 模型的结果表明，体育课降低了 BMI z 分数，并降低了五年级学生肥胖的概率。这种影响主要集中在男孩身上；我们有证据表明，这种性别差异部分归因于体育课对男孩来说是其他体力活动的补充，而对女孩来说则是替代品。这是体育课对青少年肥胖的因果影响的首批证据之一，因此至少为 CDC 建议背后的假设提供了一些支持。我们没有发现增加体育课时间会排挤学术课程时间或对成绩测试分数产生溢出效应的证据。
