منابع مشابه
Avoiding Bias in Observational Studies
T he randomized clinical trial is a well established and frequently used study design and is generally accepted as the gold standard (1). Nevertheless, many questions can only be answered with epidemiological observational studies, such as the influence of cigarette consumption on the development of lung cancer (2), the effects of sport, nutrition and overweight on cardiovascular diseases (3), ...
متن کاملAvoiding Bias in Boolean Network Statistical Studies
Stuart Kauffman and others have proposed Random Boolean networks (RBN) as models of genetic regulation in living cells. Common practice in statistical studies of RBN ensembles has been to sample Boolean rules without explicit concern for their effective connectance . We show that this practice may lead to substantial bias in estimating important dynamical features of the sparselyconnected nets ...
متن کاملAvoiding bias from weak instruments in Mendelian randomization studies.
BACKGROUND Mendelian randomization is used to test and estimate the magnitude of a causal effect of a phenotype on an outcome by using genetic variants as instrumental variables (IVs). Estimates of association from IV analysis are biased in the direction of the confounded, observational association between phenotype and outcome. The magnitude of the bias depends on the F-statistic for the stren...
متن کاملMatching with Propensity Scores to Reduce Bias in Observational Studies
In observational studies subjects are not randomly assigned to treatment and control groups. Therefore, both groups can be significantly different from each other and their differences after applying a treatment cannot be attributed to the treatment effect. Propensity scores methods offer a way to balance groups by matching treatment and control units based on a set of covariates. This paper ex...
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ژورنال
عنوان ژورنال: Deutsches Aerzteblatt Online
سال: 2009
ISSN: 1866-0452
DOI: 10.3238/arztebl.2009.0664