Environmental Science and Policy Program, Clark University, Worcester, Massachusetts, USA.
Environ Health Perspect. 2010 Sep;118(9):1318-25. doi: 10.1289/ehp.0901315. Epub 2010 Mar 8.
The National Children's Study is the most ambitious study ever attempted in the United States to assess how environmental factors impact child health and development. It aims to follow 100,000 children from gestation until 21 years of age. Success requires breaking new interdisciplinary ground, starting with how to select the sample of > 1,000 children in each of 105 study sites; no standardized protocol exists for stratification of the target population by factoring in the diverse environments it inhabits. Worcester County, Massachusetts, like other sites, stratifies according to local conditions and local knowledge, subject to probability sampling rules.
We answer the following questions: How do we divide Worcester County into viable strata that represent its health-relevant environmental and sociodemographic heterogeneity, subject to sampling rules? What potential does our approach have to inform stratification at other sites?
We developed a multivariable, vulnerability-based method for spatial sampling consisting of two descriptive indices: a hazards/stressors exposure index (comprising three proxy variables), and an adaptive capacity/sociodemographic character index (five variables). Multivariable, health-relevant stratification at the start of the study may improve detection power for environment-child health associations down the line. Eighteen strata capture countywide heterogeneity in the indices and have optimal relative homogeneity within each. They achieve comparable expected birth counts and conform to local concepts of space.
The approach offers moderate to high potential to inform other sites, limited by intersite differences in data availability, geodemographics, and technical capacity. Energetic community engagement from the start promotes local stratification coherence, plus vital researcher-community trust and co-ownership for sustainability.
国家儿童研究是美国有史以来最雄心勃勃的研究，旨在评估环境因素如何影响儿童的健康和发育。它旨在跟踪 10 万名从妊娠到 21 岁的儿童。成功需要开辟新的跨学科领域，首先是如何在 105 个研究地点中的每个地点选择 1000 多名儿童的样本；由于没有标准化的协议来根据其居住的多样化环境对目标人群进行分层，因此不存在分层的标准协议。马萨诸塞州伍斯特县与其他地点一样，根据当地条件和当地知识进行分层，符合概率抽样规则。
我们回答以下问题：如何将伍斯特县划分为可行的层，以代表其与健康相关的环境和社会人口异质性，并符合抽样规则？我们的方法在其他地点分层方面有什么潜力？
我们开发了一种基于多变量、易损性的空间抽样方法，包括两个描述性指数：一个危害/压力源暴露指数（由三个代理变量组成），以及一个适应能力/社会人口特征指数（五个变量）。在研究开始时进行多变量、与健康相关的分层可能会提高环境与儿童健康关联的检测能力。十八个层捕获了全县在指数中的异质性，并且在每个层中具有最佳的相对同质性。它们实现了可比的预期出生人数，并符合当地对空间的概念。
该方法为其他地点提供了从中受益的潜力，受限于站点间数据可用性、地理人口统计学和技术能力的差异。从一开始就积极的社区参与可以促进当地分层的一致性，以及研究人员与社区之间的信任和共同所有权，以实现可持续性。
