NBER WORKING PAPER SERIES THE EFFECTS OF EXPOSURE TO BETTER NEIGHBORHOODS ON CHILDREN: NEW EVIDENCE FROM THE MOVING TO OPPORTUNITY EXPERIMENT
NBER WORKING PAPER SERIES THE EFFECTS OF EXPOSURE TO BETTER NEIGHBORHOODS ON CHILDREN: NEW EVIDENCE FROM THE MOVING TO OPPORTUNITY EXPERIMENT
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发表时间：
2015
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通讯作者：
Raj Chetty;Nathaniel Hendren;Lawrence Katz
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作者：
Raj Chetty;Nathaniel Hendren;Lawrence Katz
“向机遇迁居”（MTO）实验为随机选取的居住在高贫困住房项目中的家庭提供住房券，使其能够迁居到贫困程度较低的社区。我们利用纳税申报单的行政数据，提供了关于MTO对儿童长期结果影响的新证据。我们发现，对于家庭迁居时年龄较小（13岁以下）的儿童来说，迁居到贫困程度较低的社区显著提高了他们的大学入学率和收入。这些儿童成年后自己所居住的社区也更好，并且成为单亲父母的可能性更低。这种处理效应是显著的：家庭在孩子不到13岁时使用实验性住房券迁居到贫困程度较低地区的儿童，在他们二十多岁时，平均年收入比对照组的11270美元高出3477美元（31%）。相比之下，对于家庭迁居时年龄超过13岁的儿童来说，同样的迁居行为如果有影响的话，也是对其长期产生负面影响，这可能是因为迁居到一个非常不同的环境所带来的干扰效应。迁居带来的收益随着儿童迁居时的年龄增长而下降，这与最近的证据一致，即童年时期处于更好环境的时长是个人长期结果的一个关键决定因素。研究结果表明，为居住在高贫困住房项目中的有年幼子女的家庭提供迁居到贫困程度较低社区的住房券，可能会降低贫困的代际持续性，并最终为纳税人带来正回报。
拉吉·切蒂
哈佛大学经济系
剑桥街1805号
马萨诸塞州剑桥市02138
以及美国国家经济研究局
chetty@fas.harvard.edu
纳撒尼尔·亨德伦
哈佛大学经济系
利陶尔中心235室
马萨诸塞州剑桥市02138
以及美国国家经济研究局
nhendren@gmail.com
劳伦斯·F·卡茨
哈佛大学经济系
马萨诸塞州剑桥市02138
以及美国国家经济研究局
lkatz@harvard.edu
居住在高贫困地区的个人在一系列经济、健康和教育成果方面比居住在贫困程度较低社区的个人表现更差。1受不同社区之间这种结果差异的推动，美国住房和城市发展部在20世纪90年代中期开展的“向机遇迁居”（MTO）实验，为随机选取的一部分居住在高贫困住房项目中的家庭提供补贴住房券，使其能够迁居到贫困程度较低的社区。MTO实验为可比家庭创造了社区环境的巨大差异，为评估改善低收入家庭社区环境的因果效应提供了机会（路德维格等人，2013）。先前对MTO实验进行评估的研究发现，迁居到贫困程度较低的地区极大地改善了成年人的心理健康、身体健康和主观幸福感以及家庭安全（例如，卡茨等人，2001；克林等人，2007；克兰佩特 - 伦德奎斯特和马西，2008；路德维格等人，2013）。但是这些研究一直发现，MTO处理措施对成年人和年龄较大青少年的收入和就业率没有显著影响，这表明社区环境对经济成功可能不太重要。在本文中，我们重新审视MTO实验，并重点关注其对家庭迁居到更好社区时年龄较小的儿童的长期影响。我们的分析是受最近的证据推动的，即个人在童年时期在特定社区度过的时间是该社区对其长期结果产生影响的一个关键决定因素。2克劳德和索思（2011）以及沃特克等人（2011）表明，在高贫困地区度过的童年比例与高中毕业等结果呈负相关。切蒂和亨德伦（2015）研究了超过500万个跨地区迁居的家庭，并使用准实验方法发现社区对儿童的结果具有因果暴露效应。特别是，童年时期在更好的地区每多度过一年，成年后的大学入学率和收入就会增加，因此对于迁居时年龄较小的儿童来说，迁居到更好地区的收益更大。根据关于童年暴露效应的这一证据，我们在MTO数据中检验两个假设。首先，我们假设迁居到贫困程度较低的地区会改善在随机分配（RA）时年龄较小的儿童的长期经济结果。其次，我们假设迁居到贫困程度较低地区的收益随着儿童迁居时的年龄增长而下降。先前的研究可参见，例如，詹克斯和迈耶（1990）、布鲁克斯 - 冈恩等人（1993）、卡特勒和格莱泽（1997）、莱文塔尔和布鲁克斯 - 冈恩（2000）以及桑普森等人（2002）。自威尔逊（1997）和詹克斯和迈耶（1990）以来，人们就已经认识到社区暴露时长可能很重要这一观点。重要的是，我们在此重点关注童年时期的暴露效应；正如我们下面所讨论的，我们没有发现成年人存在暴露效应的证据。
The Moving to Opportunity (MTO) experiment offered randomly selected families living in highpoverty housing projects housing vouchers to move to lower-poverty neighborhoods. We present new evidence on the impacts of MTO on children's long-term outcomes using administrative data from tax returns. We find that moving to a lower-poverty neighborhood significantly improves college attendance rates and earnings for children who were young (below age 13) when their families moved. These children also live in better neighborhoods themselves as adults and are less likely to become single parents. The treatment effects are substantial: children whose families take up an experimental voucher to move to a lower-poverty area when they are less than 13 years old have an annual income that is $3,477 (31%) higher on average relative to a mean of $11,270 in the control group in their mid-twenties. In contrast, the same moves have, if anything, negative long-term impacts on children who are more than 13 years old when their families move, perhaps because of the disruption effects of moving to a very different environment. The gains from moving fall with the age when children move, consistent with recent evidence that the duration of exposure to a better environment during childhood is a key determinant of an individual's long-term outcomes. The findings imply that offering vouchers to move to lower-poverty neighborhoods to families with young children who are living in highpoverty housing projects may reduce the intergenerational persistence of poverty and ultimately generate positive returns for taxpayers. Raj Chetty Department of Economics Harvard University 1805 Cambridge St. Cambridge, MA 02138 and NBER chetty@fas.harvard.edu Nathaniel Hendren Harvard University Department of Economics Littauer Center Room 235 Cambridge, MA 02138 and NBER nhendren@gmail.com Lawrence F. Katz Department of Economics Harvard University Cambridge, MA 02138 and NBER lkatz@harvard.edu Individuals who live in high-poverty areas fare worse than those who live in lower-poverty neighborhoods on a wide range of economic, health, and educational outcomes.1 Motivated by such disparities in outcomes across neighborhoods, the Moving to Opportunity (MTO) experiment of the U.S. Department of Housing and Urban Development offered a randomly selected subset of families living in high-poverty housing projects subsidized housing vouchers to move to lower-poverty neighborhoods in the mid-1990s. The MTO experiment generated large differences in neighborhood environments for comparable families, providing an opportunity to evaluate the causal effects of improving neighborhood environments for low-income families (Ludwig et al. 2013). Previous research evaluating the MTO experiment has found that moving to lower-poverty areas greatly improved the mental health, physical health, and subjective well being of adults as well as family safety (e.g., Katz et al. 2001, Kling et al. 2007, Clampet-Lundquist and Massey 2008, Ludwig et al. 2013). But these studies have consistently found that the MTO treatments had no significant impacts on the earnings and employment rates of adults and older youth, suggesting that neighborhood environments might be less important for economic success. In this paper, we revisit the MTO experiment and focus on its long-term impacts on children who were young when their families moved to better neighborhoods. Our analysis is motivated by recent evidence that the amount of time individuals spend in a given neighborhood during their childhood is a key determinant of that neighborhood’s effects on their long-term outcomes.2 Crowder and South (2011) and Wodtke et al. (2011) show that the fraction of childhood spent in high-poverty areas is negatively correlated with outcomes such as high-school completion. Chetty and Hendren (2015) study more than five million families that move across areas and find that neighborhoods have causal exposure effects on children’s outcomes using quasi-experimental methods. In particular, every year spent in a better area during childhood increases college attendance rates and earnings in adulthood, so the gains from moving to a better area are larger for children who are younger at the time of the move. In light of this evidence on childhood exposure effects, we test two hypotheses in the MTO data. First, we hypothesize that moving to a lower-poverty area improves long-term economic outcomes for children who were young at the point of random assignment (RA). Second, we hypothesize that the gains from moving to a lower-poverty area decline with a child’s age at move. Prior work has See, for example, Jencks and Mayer (1990), Brooks-Gunn et al. (1993), Cutler and Glaeser (1997), Leventhal and Brooks-Gunn (2000), and Sampson et al. (2002). The idea that the length of exposure to neighborhoods might matter has been recognized since Wilson (1987) and Jencks and Mayer (1990). Importantly, we focus here on exposure effects during childhood ; as we discuss below, we find no evidence of exposure effects for adults.