Ecologic versus individual-level sources of bias in ecologic estimates of contextual health effects
Ecologic versus individual-level sources of bias in ecologic estimates of contextual health effects
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DOI：
10.1093/ije/30.6.1343
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发表时间：
2001-12-01
影响因子：
7.7
通讯作者：
Greenland, S
中科院分区：
文献类型：
--
作者：
Greenland, S
许多作者试图通过声称这些研究的目标是估计生态（背景或群体水平）效应而不是个人水平效应来为生态（总体）研究辩护。这些尝试的批评者指出，尽管有声明，但生态效应估计不可避免地被用作个体效应的估计。A.更微妙的问题是，个体效应分布的生态变化可能会使环境效应的生态估计产生偏差。导致这种偏见的条件是合理的，甚至可能在生态社会因素和健康结果的研究中很常见，因为社会背景在典型的分析单位（行政区域）中不是随机的。根据定义，生态学数据只包含对个体定义的混杂因素和结果的联合分布的边缘观察，因此既不能识别背景效应也不能识别个体水平效应。虽然生态学研究在适当的警告下仍然是有用的，但它们的问题可以通过多层次研究设计得到更好的解决，这种设计可以获得和使用个人以及群体水平的数据。尽管如此，这些研究往往共享某些特殊的：生态研究的问题，包括问题，由于不适当的聚集和问题，由于协变量分布的时间变化。
A number of authors have attempted to defend ecologic (aggregate) studies by claiming that the goal of those Studies is estimation of ecologic (contextual or group-level) effects rather than individual-level effects. Critics of these attempts point out that ecologic effect estimates are inevitably used as estimates of individual effects, despite disclaimers. A. more subtle problem is that ecologic variation in the distribution of individual effects can bias ecologic estimates of contextual effects. The conditions leading to this bias are plausible and perhaps even common in studies of ecosocial factors and health outcomes because social context is not randomized across typical analysis units (administrative regions). By definition, ecologic data contain only marginal observations on the joint distribution of individually defined confounders and outcomes, and so identify neither contextual nor individual-level effects. While ecologic studies can still be useful given appropriate caveats, their problems are better addressed by multilevel study designs, which obtain and use individual as well as group-level data. Nonetheless, such studies often share certain special: problems with ecologic studies, including problems due to inappropriate aggregation and problems due to temporal changes in covariate distributions.