Ecologic versus individual-level sources of bias in ecologic estimates of contextual health effects
نویسندگان
چکیده
منابع مشابه
Ecologic versus individual-level sources of bias in ecologic estimates of contextual health effects.
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 ecolog...
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two groups of students were assigned as experimental and control ones, and were given instruction on directed reading-thinking activities and after some treatment, they were post-tested. although the initial pre-test did not show any significant differences, the final post-test result revealed that the cooperative reading comprehension helped the experimental group. the cooperative students’...
15 صفحه اولBias magnification in ecologic studies: a methodological investigation
BACKGROUND As ecologic studies are often inexpensive to conduct, consideration of the magnitude and direction of ecologic biases may be useful in both study design and sensitivity analysis of results. This paper examines three types of ecologic bias: confounding by group, effect measure modification by group, and non-differential exposure misclassification. METHODS Bias of the risk difference...
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Ecologic (aggregate) data are widely available and widely utilized in epidemiologic studies. However, ecologic bias, which arises because aggregate data cannot characterize within-group variability in exposure and confounder variables, can only be removed by supplementing ecologic data with individual-level data. Here the authors describe the two-phase study design as a framework for achieving ...
متن کاملEcologic studies revisited.
Ecologic studies use data aggregated over groups rather than data on individuals. Such studies are popular because they use existing databases and can offer large exposure variation if the data arise from broad geographical areas. Unfortunately, the aggregation of data that define ecologic studies results in an information loss that can lead to ecologic bias. Specifically, ecologic bias arises ...
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ژورنال
عنوان ژورنال: International Journal of Epidemiology
سال: 2001
ISSN: 1464-3685,0300-5771
DOI: 10.1093/ije/30.6.1343