Food Assistance, Diet and Body Weight Status among WIC Eligible Children

摘要 妇女、婴儿和儿童特别补充营养计划(WIC)目前提供 每月约有800万名妇女、婴儿和儿童。其中超过一半的人从 还有补充营养援助计划(SNAP)。符合WIC资格的儿童(WEC)是婴儿和 家庭收入低于联邦贫困水平185%的5岁以下儿童。如果他们的 家庭收入低于联邦贫困水平的130%，他们也有资格享受SNAP。WIC和SNAP 他们的援助方式截然不同：WIC提供营养食品包装，而SNAP提供 购买食品的现金等值福利。然而，即使有了这些计划，WIC儿童仍然可以体验到 严重的营养风险：例如，2014年，29.4%的2-4岁儿童超重。广泛的研究 这表明SNAP参与者对食物选择的扭曲，这可能与超重有关。 因此，需要更多的研究来了解WIC和SNAP参与对WEC的影响 营养结果。 WIC在2009年对食品包装进行了重大改革，这是40年来的第一次。 评估2009年WIC修订版的文献存在几个局限性：首先，没有全国性的研究 研究了WIC参与的影响；第二，没有研究控制WIC计划中的选择偏差 参与，这导致了对该计划效果的错误估计；最后，没有研究检查 SNAP对WEC膳食摄入量和体重状况的边际影响。该项目的中心目标是 检查WIC和/或SNAP参与对符合WIC条件的儿童膳食摄入量和身体的影响 自2009年WIC修订以来的体重状况。我们的主要假设是WIC和SNAP提供互补 食物福利，参与其中一项或两项计划都能促进健康饮食和体重状况。我们 建议使用2009-2014年国家健康和营养检查调查(NHANES)来检查WIC 和SNAP参与选择在具有全国代表性的合格儿童样本中进行。说明，说明 对于选择偏差，我们提出了三种统计方法，倾向分数(PS)、工具变量(IV)和 回归不连续(RD)。PS和IV都有局限性：PS不能解释未观察到的偏差 然而，由于难以找到合适的工具变量，IV常常受到挑战。RD可以 从理论上克服这些限制，并利用主题被分配到 治疗组或对照组以一个截止分数为基础，这是本项目的收入资格。虽然RD是一种 已被广泛应用于项目评估，但很少应用于项目评估 WIC/SNAP评估。有了三种互补的方法，我们将能够构建建立 WIC和/或SNAP参与与2009年WIC修订后的营养结果之间的因果关系。

ABSTRACT The Special Supplemental Nutrition Program for Women, Infants, and Children (WIC) currently serves approximately 8 million women, infants, and children monthly. Over half of them receive benefits from the Supplemental Nutrition Assistance Program (SNAP) as well. WIC-eligible children (WEC) are infants and children younger than 5 years old with household incomes lower than 185% of the federal poverty level. If their household income is below 130% of the federal poverty level, they are also eligible for SNAP. WIC and SNAP dramatically differ in their assistance approach: WIC provides nutritious food packages, while SNAP provides cash-equivalent benefits to buy foods. However, even with these programs, WIC children still experience significant nutrition risks: e.g., 29.4% of children aged 2-4 were overweight in 2014. Extensive research suggests a distortion of food choices among SNAP participants, which could be linked to being overweight. Therefore, more research is needed to understand the effects of WIC and SNAP participation on WEC’s nutritional outcomes. WIC implemented a significant overhaul of the food package in 2009, the first time in four decades. Several limitations exist in the literature that has evaluated the 2009 WIC revision: First, no national study has examined WIC participation effects; second, no studies have controlled for selection bias in WIC program participation, which leads to erroneous estimates of the program’s effects; finally, no studies have examined the marginal effects of SNAP on WEC’s dietary intake and body weight status. This project’s central aim is to examine the effects of WIC and/or SNAP participation on WIC-eligible children’s dietary intakes and body weight status since the 2009 WIC revision. Our main hypothesis is that WIC and SNAP provide complementary food benefits, and participation in either or both programs promotes healthy diets and weight statuses. We propose to use the National Health and Nutrition Examination Survey (NHANES) 2009-2014 to examine WIC and SNAP participation choices in a nationally representative sample of eligible children. To account for selection bias, we propose three statistical techniques, propensity score (PS), instrumental variable (IV), and regression discontinuity (RD). PS and IV both have limitations: PS cannot account for unobserved biasing factors, while IV is often challenged due to difficulty in finding a proper instrumental variable. RD can theoretically overcome these limitations and take advantage of the design that subjects are assigned into the treatment or control group based on a cutoff score, which is income eligibility in this project. Although RD is a well-validated technique and has been applied to program evaluation extensively, it is rarely applied to WIC/SNAP evaluation. With three complementary methods, we will be able to build the initial step to establish causality between WIC and/or SNAP participation and nutritional outcomes following the 2009 WIC revision.