منابع مشابه
Bias due to participant overlap in two‐sample Mendelian randomization
Mendelian randomization analyses are often performed using summarized data. The causal estimate from a one-sample analysis (in which data are taken from a single data source) with weak instrumental variables is biased in the direction of the observational association between the risk factor and outcome, whereas the estimate from a two-sample analysis (in which data on the risk factor and outcom...
متن کاملRandomization in clinical trials: can we eliminate bias?
Randomization plays a fundamental role in clinical trials. While many modern clinical trials employ restricted, stratifiedor covariate-adaptive randomization designs that pursue balance in treatment assignments and balance across important covariates, some clinical trials call for response-adaptive or covariate-adjusted response-adaptive (CARA) randomization designs to...
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 کاملOn Invariant Post Randomization for Statistical Disclosure Control
In this paper, we investigate certain operational and inferential aspects of invariant PRAM (post randomization method) as a tool for disclosure limitation of categorical data. Invariant PRAMs preserve unbiasedness of certain estimators, but inflate their variances and distort other attributes. We introduce the concept of strongly invariant PRAM, which does not affect data utility or the proper...
متن کاملChallenges and Solutions to Pre- and Post-Randomization Subgroup Analyses
Subgroup analyses are commonly performed in the clinical trial setting with the purpose of illustrating that the treatment effect was consistent across different patient characteristics or identifying characteristics that should be targeted for treatment. There are statistical issues involved in performing subgroup analyses, however. These have been given considerable attention in the literatur...
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ژورنال
عنوان ژورنال: Journal of Manual & Manipulative Therapy
سال: 2020
ISSN: 1066-9817,2042-6186
DOI: 10.1080/10669817.2020.1739153