COVARIANCE ADJUSTMENT IN STUDIES INVOLVING OBSERVATIONAL FACTORS OR COVARIATES INFLUENCED BY TREATMENTS
نویسندگان
چکیده
منابع مشابه
Covariance Adjustment in Randomized Experiments and Observational Studies
By slightly reframing the concept of covariance adjustment in randomized experiments, a method of exact permutation inference is derived that is entirely free of distributional assumptions and uses the random assignment of treatments as the “reasoned basis for inference.” This method of exact permutation inference may be used with many forms of covariance adjustment, including robust regression...
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BACKGROUND Univariate meta-analysis (UM) procedure, as a technique that provides a single overall result, has become increasingly popular. Neglecting the existence of other concomitant covariates in the models leads to loss of treatment efficiency. Our aim was proposing four new approximation approaches for the covariance matrix of the coefficients, which is not readily available for the multiv...
متن کاملCalibrating sensitivity analyses to observed covariates in observational studies.
In medical sciences, statistical analyses based on observational studies are common phenomena. One peril of drawing inferences about the effect of a treatment on subjects using observational studies is the lack of randomized assignment of subjects to the treatment. After adjusting for measured pretreatment covariates, perhaps by matching, a sensitivity analysis examines the impact of an unobser...
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BACKGROUND Previous studies have assessed the validity of the observational study design by comparing results of studies using this design to results from randomized controlled trials. The present study examined design features of observational studies that could have influenced these comparisons. METHODS To find at least 4 observational studies that evaluated the same treatment, we reviewed ...
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ژورنال
عنوان ژورنال: Conference on Applied Statistics in Agriculture
سال: 1997
ISSN: 2475-7772
DOI: 10.4148/2475-7772.1300