搬离贫民区就能脱贫吗？

20年前，标志性书籍《真正的穷人》(The Truly Disadvantaged)中强有力的论述，以及关于社群隔离的负面效应的权威研究，使得联邦贫困问题专家深受启发，于是他们启动了一项政府实验项目，让855户低收入家庭从贫困城区的公租屋中搬到经济状况更好的社区。这些家庭绝大多数为非洲裔和西语裔。
项目的结果引发了激烈争论。
该计划名为“搬向机遇”（Moving to Opportunity，简称MTO），始于比尔·克林顿(Bill Clinton)的第一个总统任期。当时，联邦住房与城市发展部从巴尔的摩、波士顿、芝加哥、洛杉矶和纽约随机选择了一大批有小孩的低收入家庭。其中98%的家庭由女性支撑；63%为黑人、32%为西语裔、3%为白人；26%有工作、76%领救济，以2009年价格折算的家庭平均收入为1万2709美元（当时约合8.7万元人民币）。
参与项目的共有4604户家庭，分为三组。一个实验组有1819户，政府向他们提供了“《住房法案》第8节规定的租赁补助券或代金券，但只能在1990年贫困率低于10%的人口普查区内使用”；855户接受了提议，参与到这项研究中。第二组有1346户，政府向他们提供的是更为传统的租赁劵，可以用在任何社区；848户对此予以接受。
此外还有1439户家庭留在公租屋社区里，成为研究中的对照组。联邦住房与城市发展部表示，这一搬迁项目的目的在于，测试“受助家庭进入低贫困社区后在住房、就业和教育成就方面的长期效应。”研究人员还研究了搬迁对领取租赁劵人员的健康影响。
《美国经济评论》(American Economic Review)2013年5月刊发表了一篇题为《低收入家庭的长期社区效应：以“搬向机遇”项目为例》(Long-Term Neighborhood Effects on Low-Income Families: Evidence From Moving to Opportunity)的论文。文中发现，相关家庭通过MTO项目迁出高贫困公租屋社区的10到15年后，结果好坏参半。
论文的第一作者芝加哥大学(University of Chicago)经济学教授延斯·路德维格(Jens Ludwig)是负责MTO最终评审的项目主管。他表示，的确存在一些积极进展。他和六名论文合著者发现，受试者在“几项关键的成人心理与生理健康指标”上有所进步，比如糖尿病与肥胖症的风险显著降低，以及“幸福感”有所提升。
不过，路德维格的研究还发现，“光是变动居住社区，或许并不足以改善底层家庭的就业或学业成就。”他在文中指出，这种允许家庭搬迁到“低贫困”地区的特殊租赁券“在一些方面没有可观察到的持续效应，不管是经济上的自给自足，还是孩子的教育成就，就连实验伊始年龄尚小、没有入学的孩子也如此。”
在民主党“三维智库”(Third Way)本周发表的一篇后续文章中，路德维格提出了类似结论。
美国的一些最为权威的贫困问题研究者，比如哈佛社会学教授、《真正的穷人》的作者威廉·朱利叶斯·威尔逊(William Julius Wilson)认为，MTO项目存在设计缺陷，从而引来了就业与学业方面未能有所改善的不妥结论。
在写给《纽约时报》的电子邮件中，威尔逊指出，MTO项目里离开公租屋的家庭还是搬到了隔离社区，远离就业机会，而学校的糟糕程度也不相上下，子女往往还是去同样的地方上学。他们的社会状况只比之前好上一星半点。
此外，威尔逊写道，参与项目的成年人“此前一生均过着极为底层的生活，无论到新社区里住了多久，早年所受的影响也不能完全消除。”
在《美国社会学期刊》(American Journal of Sociology)2008年发表的一篇论文中，哈佛社会学教授罗伯特·桑普森(Robert Sampson)提出，MTO项目还不如叫做“搬向不平等”。
桑普森在写给时报的电子邮件中指出，参与MTO项目的许多成年人本已在极端贫困中浸淫了几十年，而他们的子女在项目开始的时候平均年龄为11岁，也已经历了早年的逆境。“结果，”他写道。“在这样的实验设计之下，很难、甚至是不可能研究发展效应，”因为这种设计没有揭示出“严重贫困的滞后效应”。
虽然参与MTO项目的家庭搬到贫困与犯罪状况稍好的社区，其新家所处的地段绝不是什么欣欣向荣之所。桑普森绘制了一幅芝加哥地图，其中显示，根据贫困率、失业状况、领取救济状况、女性支撑家庭的数量、种族构成和儿童人口密度进行衡量的综合指标，绝大多数MTO家庭迁去的地方仍是“底层人口高度集中”的社区。
在另一项研究中，来自兰德公司(RAND Corporation)的研究员希瑟·施瓦茨(Heather Schwartz)得出的结论也与桑普森和威尔逊更为一致。在马里兰州蒙哥马利县，施瓦茨研究了大多为少数族裔的低收入家庭学生的表现。该县属于华盛顿的郊区，经济富裕，以白人居民为主。
蒙哥马利县采用了让公租屋散布在各处的政策。租户中，72%为黑人，16%为西语裔。按照这一政策，这些租户住在以白人为主的中产阶级公寓楼里。
这样，施瓦茨就能够将居住在公租屋里的孩子的学业表现与大量来自富裕白人家庭的同学进行比较；对照组的孩子上的学校则大部分容纳的是少数族裔学生，而且家庭贫困率要高得多。
结果相当惊人。住在公租屋的低收入少数族裔家庭的孩子，一开始的时候数学分数相当。但是七年之后，同学中贫困率少于20%的孩子，比起同学中贫困率在20%到80%之间的孩子，成绩遥遥领先。图1的曲线显示了其中的差异。绿线代表那些上了较为富裕学校的贫困家庭孩子（定义为领取“免费和优惠餐”[FARM]的学生）的数学分数，红线则代表所上学校里领FARM比例要高得多的贫困家庭孩子的数学成绩。
也许，贫困代际传递最为重要的因素是，婴幼儿时期极端贫困带来的长期效应。
美国儿科学会(American Academy of Pediatrics)2011年发表了一篇研究论文，题为《婴幼儿时期逆境与有害压力的终生影响》(The Lifelong Effects of Early Childhood Adversity and Toxic Stress)。文中显示，“早期经历和环境影响可在遗传倾向方面留下持久痕迹，从而影响正在成型的大脑构造和长期健康。”这项儿科研究认为，“早期逆境与后来在学习、行为及身心健康上的缺陷有关。”
婴幼儿时期的压力会影响“大脑结构的发育”，从而“导致后来在学习、行为和健康方面基础薄弱。”
从这个角度看来，MTO项目的研究结果似乎并不意外。评估显示，比起留在公租屋社区的家庭，拿到租赁券去低贫困社区居住的MTO参与者，在就业率与收入平等方面没有进展，他们的子女的学业表现也并无进步。
首先，参与者似乎只获得了不多的住房咨询，此外几乎没有获得其他支持。但更加深层的问题在于：多代贫穷可不仅仅是一个住房问题，这一点不言而喻。即便是最具善意的单一措施，也不可能解决得了它。
综合多种措施可能会更加有效。为弱势群体境况代代相传的现象，寻找更加深层的原因，这是一个持续进行的研究议程。最近的一些论文，比如《弱势处境的传承：居住多代的社区对认知能力的影响》 (The Legacy of Disadvantage: Multigenerational Neighborhood Effects on Cognitive Ability)和《从时间角度看居民区效应：长期处于弱势境地对高中毕业状况的影响》 (Neighborhood Effects in Temporal Perspective: The Impact of Long-Term Exposure to Concentrated Disadvantage on High School Graduation)，都属于这个进程的一部分。
MTO这项研究（目前已经完成）遭受的批评，指出了可供探索的一些新途径。尽管对于租赁券计划结果的解释，变得富有争议，而且有点政治化，这个辩论本身却可能具有建设性。
巨大改变是有可能的实现的，但下一步需要投入更多的资源，进行更先进的研究设计。
未来可能要做的事情，包括对“知识就是力量”计划(KIPP)等完全沉浸式学校系统进行以证据为基础的评估，以及更好地了解贫穷对大脑发育的影响。也许最重要的是，在“社区或学校”的讨论中，把侧重点放在缩小不同族裔的考分差异上，哈佛大学经济学家小罗兰·弗赖尔(Roland Fryer Jr.)和芝加哥大学经济学家史蒂芬·莱维特(Steven Levitt)说。两人认为，在初中结束前消除考分差距，“可能会是减少种族工资不平等过程的一个重要组成部分。”
两位作者写道，“和早期的研究形成鲜明对比的是，我们的研究证明，当我们对少数协变量进行了控制后，黑人和白人进入幼儿园前的考分差距就消失了，”他们还表示，“这是一个暗示性的证据，显示学校教学质量的差异，可能是导致考分差距形成的重要原因之一。我们也测试了用来解释为什么黑人的成绩每况愈下的其他假设，但它们没有获得任何实证的支持。”
对于弱势境地代代相传的情况，我们才刚刚开始有所了解；必须找出一个更好的办法，来对此加以干预，无论这个办法是基于教育的，还是基于居民区的，还是双管齐下。否则，我们怎样才能阻止它继续传递下去呢？（更多资讯请浏览中国进出口网）

Twenty years ago, federal poverty experts, inspired by the forceful arguments in the landmark book “The Truly Disadvantaged,” as well as by definitive research on the harmful effects of segregation, initiated a government experiment that moved 855 low-income predominantly African-American and Hispanic families out of public housing in poverty-stricken urban areas into less impoverished neighborhoods.
The results of the project have provoked an intense debate.
Under the aegis of the “Moving to Opportunity” program, begun during the first administration of Bill Clinton, the Department of Housing and Urban Development randomly seleced a large pool of low-income families with children living in public housing in Baltimore, Boston, Chicago, Los Angeles and New York. Ninety-eight percent of the families were headed by women; 63 percent were black, 32 percent Hispanic, and 3 percent white; 26 percent were employed, 76 percent were receiving welfare, and families had an average income of $12,709 in 2009 dollars.
These families, 4604 of them, to be exact, were then divided into three groups. An experimental group of 1,819 families was offered “Section 8 rental assistance certificates or vouchers that they could use only in census tracts with 1990 poverty rates below 10 percent”; 855 accepted the offer and became part of the study. A second group of 1,346 families was offered more traditional “Section 8” rent subsidy vouchers that could be used in any neighborhood; 848 accepted.
A control group composed of 1,439 families stayed in public housing and became part of the study. The purpose of the relocation initiative, according to Department of Housing and Urban Development, was to test the “long-term effects of access to low-poverty neighborhoods on the housing, employment and educational achievements of the assisted households.” Researchers also studied how relocation affected the health of those who accepted vouchers.
A paper published in the May 2013 issue of the American Economic Review, “Long-Term Neighborhood Effects on Low-Income Families: Evidence from Moving to Opportunity,” found that after 10 to 15 years, moving out of high-poverty public housing through the M.T.O. program showed mixed results.
There were some positive developments, according to the primary author of the paper, Jens Ludwig, a professor of economics at the University of Chicago and the project director for a final assessment of the M.T.O. program. Ludwig and his six co-authors found improvement in “several key adult mental and physical health outcomes.” These included significantly lowered risk of diabetes and obesity, as well as an improved level of “subjective well-being.”
But the Ludwig study also found that “changing neighborhoods alone may not be sufficient to improve labor market or schooling outcomes for very disadvantaged families.” Ludwig reported that this particular form of assistance from HUD –a housing voucher that allowed recipients to move into a “low poverty” area – had “no consistent detectable impacts on adult economic self-sufficiency or children’s educational achievement outcomes, even for children who were too young to have enrolled in school at baseline.”
Ludwig reported similar findings in a follow-up essay published this week by Third Way, a Democratic think tank.
Some of the nation’s most prominent poverty researchers, including William Julius Wilson, a professor of sociology at Harvard and the author of “The Truly Disadvantaged,” consider that the design of the M.T.O. project was flawed, leading to unwarranted conclusions about the lack of improvement in employment and schooling.
Wilson pointed out in an email to The Times that the families in the study who left public housing moved into segregated neighborhoods nonetheless, far from employment opportunities and with equally bad schools – often the same schools. Social conditions were only marginally better than those they had left.
In addition, Wilson wrote, the adults in the program “had been exposed all their lives to the effects of severely concentrated disadvantage, and no matter how long they are followed in their new neighborhoods, the effects of those earlier years are not fully erased.”
Robert Sampson, a professor of sociology at Harvard, argued in a 2008 essay published in the American Journal of Sociology that the project should have been called “Moving to Inequality.”
Sampson pointed out in an email that many of the adults in the program had lived in extreme poverty for decades and that the children, who were on average 11 years old when they entered the program, had spent their early years living in adversity. “The result,” he wrote, “is that developmental effects are difficult if not impossible to study in the research design,” which does not reveal the “lagged effects of severe disadvantage.”
While the M.T.O. participants moved to neighborhoods with somewhat less poverty and crime, their new homes were by no means in flourishing sections of the city. Sampson produced a map of Chicago showing that the overwhelming majority of families moved to areas that still qualified as communities of “high concentrated disadvantage” based on a measure combining poverty rates, unemployment, welfare receipt, female-headed households, racial composition and density of children.
In a separate study, Heather Schwartz, a researcher at the RAND Corporation, reached conclusions more in line with Sampson’s and Wilson’s. Schwartz examined the performance of low-income, mostly minority students in Montgomery County, Md., an affluent majority-white suburb of Washington.
The county adopted policies dispersing public housing so that many of the tenants, who were 72 percent black and 16 percent Hispanic, were housed in middle-class, largely white apartment complexes.
This allowed Schwartz to measure the performance of children from public housing who attended schools with large numbers of well-off white students, against the performance of those who attended schools with largely minority populations and much higher poverty rates.
The results are striking. The low-income minority children from public housing all started with similar math scores. But after seven years, those who went to schools wher fewer than 20 percent of their classmates were poor shot ahead of those who went to schools wher 20 to 80 percent of their classmates were poor. This difference in trajectories is shown in Figure 1, in which the green line tracks math scores for poor children (defined as those receiving “free and reduced-priced meals” – a.k.a. FARM recipients) in relatively affluent schools, and the red line tracks math scores for poor children attending schools with much higher percentages of fellow students receiving FARM assistance.
Perhaps the most important factors in the intergenerational transmission of disadvantage are the long-term effects on infants of living in extreme poverty.
A study published by the American Academy of Pediatrics in 2011, “The Lifelong Effects of Early Childhood Adversity and Toxic Stress,” shows that “early experiences and environmental influences can leave a lasting signature on the genetic predispositions that affect emerging brain architecture and long-term health.” The pediatric study links “early adversity to later impairments in learning, behavior, and both physical and mental well-being.”
Early childhood stress affects the “developing architecture of the brain” in ways “that create a weak foundation for later learning, behavior and health.”
Looked at this way, the M.T.O. findings — that participants who were given vouchers for housing in low-poverty neighborhoods made no gains in employment and wage equality compared with those left behind in public housing and that their children showed no improvement in school performance — do not seem surprising.
For one thing, participants appear to have been given little or no support other than modest housing counseling. But the issue is deeper than that: Multigenerational poverty is self-evidently more than a question of housing. It is unlikely to yield to even the best-intentioned one-dimensional approach.
Multifactorial approaches may be more productive. Recent papers such as “The Legacy of Disadvantage: Multigenerational Neighborhood Effects on Cognitive Ability” and “Neighborhood Effects in Temporal Perspective: The Impact of Long-Term Exposure to Concentrated Disadvantage on High School Graduation” are part of a continuing research agenda looking more profoundly into the causes of the intergenerational transmission of disadvantage.
The criticism of the M.T.O. study (which is now complete) points to new avenues for exploration. Even though the interpretation of the results of the housing voucher program has become contentious and somewhat politicized, the debate itself has the potential to be constructive.
Significant change is possible, but more resources and more sophisticated research design will be a necessary next step.
Lines of possible future inquiry include evidence-based evaluations of total-immersion school systems like the KIPP program and a better understanding of the effects of poverty on brain development. Perhaps most importantly, in the debate over “neighborhoods or schools,” would be a concentrated focus on reducing racial and ethnic discrepancies in test scores, according to the economists Roland Fryer Jr. of Harvard and Steven Levitt of the University of Chicago. Fryer and Levitt argue that the elimination of “the test score gap that arises by the end of junior high school may be a critical component of reducing racial wage inequality.”
The two authors write, “we demonstrate that in stark contrast to earlier studies, the black-white test score gap among incoming kindergartners disappears when we control for a small number of covariates.” They add, “There is suggestive evidence that differences in school quality may be an important part of the explanation. None of the other hypotheses we test to explain why blacks are losing ground receive any empirical backing.”
We have to figure out a better way to approach intervention, whether it’s education-based or neighborhood-based or both. Otherwise how can we interrupt the intergenerational transmission of disadvantage we are only beginning to understand?
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