Selection Bias, Confounding, or Information Bias?
نویسندگان
چکیده
منابع مشابه
Selection bias and information bias in clinical research.
The internal validity of an epidemiological study can be affected by random error and systematic error. Random error reflects a problem of precision in assessing a given exposure-disease relationship and can be reduced by increasing the sample size. On the other hand, systematic error or bias reflects a problem of validity of the study and arises because of any error resulting from methods used...
متن کاملBIAS & CONFOUNDING M . Tevfik DORAK
Introduction In epidemiologic research, it is essential to avoid bias, to control confounding and to undertake accurate replication. Bias, confounding and random variation/chance are the non-causal reasons for an association between an exposure and outcome. These major threats to internal validity of a study should always be considered as alternative explanations in the interpretation. Bias is ...
متن کاملAssessing bias: the importance of considering confounding
When a difference in an outcome (eg, pain) between exposures (eg, treatment groups) is observed, one needs to consider whether the effect is truly because of exposure or if alternate explanations are possible. As we discussed in the previous issue of EBSJ, to evaluate the validity of a research study, factors that might distort the true association and/or influence its interpretation need to be...
متن کاملEcological bias, confounding, and effect modification.
Ecological bias is sometimes attributed to confounding by the group variable (ie the variable used to define the ecological groups), or to risk factors associated with the group variable. We show that the group variable need not be a confounder (in the strict epidemiological sense) for ecological bias to occur: effect modification can lead to profound ecological bias, whether or not the group v...
متن کاملSelection Bias
data in Haneuse et al. [1] . The risk ratio of dementia by exposure in the total target population is 2.0, and is the true association (there is no confounding in our simple DAG; fig. 1 ). Table 1 shows the expected distribution by exposure and outcome by strata of dead/alive under the following assumptions: half of the population dies; there is a risk ratio of death for the exposed compared to...
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ژورنال
عنوان ژورنال: Hypertension
سال: 2007
ISSN: 0194-911X,1524-4563
DOI: 10.1161/hypertensionaha.107.092320