Peer Effects on Weight Loss and Other Health Behaviors

描述(由申请者提供)：了解青少年超重上升的原因并制定有效的公共卫生政策来扭转目前的上升趋势是至关重要的。青少年与体重相关的行为(例如，饮食和体力活动)往往受到同龄人行为的影响。如果同伴确实对青少年体重有影响，那么旨在减少青少年超重的政策可能会产生社会乘数效应，即政策的总体影响大于单个参与者。我们的研究将首次评估同伴对青少年体重相关行为的影响，同时明确控制潜在的反向因果关系(互惠效应)和青少年对同伴的选择(选择)。考虑到这些影响很重要，因为如果青少年行为和同龄人行为之间的相关性不是因果关系，那么政策就不会带来社会乘数。拟议的研究将涉及以下具体目标：目标1：确定同龄人的体重影响青少年自身体重的机制。利用国家青少年健康纵向研究(Add Health)的数据，我们将检查同伴对以下青少年体重相关行为的影响：(A)自我感觉体重，(B)身体活动水平，(C)饮食模式，(D)体重管理活动。Add Health允许我们在几个级别上定义同龄人组，包括使用提名的友谊关系和年级级别。将使用几种经验策略来解决目标1，包括根据外部变量估计朋友选择的多阶段程序；在学校内部不受选择影响的年级水平的同伴的替代定义；使用Add Health的前两波控制来控制反向因果关系的同伴变量的滞后值；以及使用每个学校的指标变量来控制学校层面的混杂(未观察到的)影响。我们将测试性别差异对同龄人的影响。AIM 1的结果将帮助政策制定者针对那些有可能从目标青少年向他们的同龄人产生最大溢出效应的行为。目标2：估计针对青少年超重的政策所隐含的社会乘数。使用目标1的结果，我们将计算每个与体重相关的行为的社会乘数的大小。了解社会乘数的大小对于评估旨在改善青少年体重的公共卫生政策的效力和成本效益至关重要。如果不考虑社会乘数，就会低估有效的公共卫生政策对人口层面的影响，以减少青少年超重。 公共卫生相关性：如果同伴对青少年体重有影响，那么旨在减少青少年超重的政策可能会产生社会乘数效应，其中政策的总体影响大于单个参与者。这项研究将提供对青少年体重相关行为的社会乘数的准确估计，这对于评估公共卫生政策的有效性至关重要。如果不考虑社会乘数，就会低估有效的公共卫生政策对人口层面的影响，以减少青少年超重。

DESCRIPTION (provided by applicant): It is vitally important to understand the causes of the rise in adolescent overweight and to develop effective public health policies to reverse the current upward trend. Adolescent weight-related behavior (e.g., diet and physical activity) is often influenced by the behavior of peers. If peers do have an influence on adolescent weight, then policies aimed at reducing adolescent overweight could have social multiplier effects in which the impact of the policy is larger in the aggregate than for individual participants. Our study will be the first to estimate the influence of peers on adolescent weight-related behavior while explicitly controlling for potential reverse causation (reciprocal effects) and adolescents' choice of peers (selection). Accounting for these effects is important because if the correlation between adolescent behavior and peers' behavior is not causal, then policies would not lead to social multipliers. The proposed research will address the following specific aims: Aim 1: To identify the mechanisms through which peers' weight affects an adolescent's own weight. Using data from the National Longitudinal Study of Adolescent Health (Add Health), we will examine the influence of peers on the following adolescent weight-related behaviors: (a) self-perception of weight, (b) physical (in) activity levels, (c) eating patterns, and (d) weight management activities. Add Health allows us to define peer groups at several levels, including using nominated friendship relationships and grade level. Several empirical strategies will be used to address Aim 1, including a multistage procedure that estimates friend selection based on exogenous variables; an alternative definition of peers at the grade level, which within schools is not affected by selection; lagged value of peer variables using the first two waves of Add Health to control for reverse causation; and the use of indicator variables for each school to control for confounding (unobserved) influences at the school level. We will test for gender differences in the influence of peers. Results for Aim 1 will help policy makers target those behaviors that have the potential for the largest spillovers from targeted adolescents to their peers. Aim 2: To estimate the implied social multiplier for policies aimed at adolescent overweight. Using the results from Aim 1, we will calculate the size of social multipliers for each weight-related behavior. Understanding the magnitude of the social multiplier is crucial for assessing the effectiveness and cost-effectiveness of public health policies aimed at improving adolescent weight. Failure to account for social multipliers would undervalue the population-level impact of effective public health policies to reduce adolescent overweight. PUBLIC HEALTH RELEVANCE: If peers have an influence on adolescent weight, then policies aimed at reducing adolescent overweight could have social multiplier effects in which the impact of the policy is larger in the aggregate than for individual participants. The accurate estimates of social multipliers for adolescent weight-related behavior that will be provided by this research are crucial for evaluating the effectiveness of public health policies. Failure to account for social multipliers would undervalue the population-level impact of effective public health policies to reduce adolescent overweight.