What is the difference between selection bias and confounding?
What is the difference between selection bias and confounding?
While inadequate control of confounding is the most-often cited source of potential bias, selection bias which arises when patients are differentially excluded from analyses is a distinct phenomenon with distinct consequences: confounding bias compromises internal validity while selection bias compromises external …
What are effect modifiers?
Effect modification describes the situation where the magnitude of the effect of an exposure variable on an outcome variable differs depending on a third variable. In other words the presence or absence of an effect modifier changes the association of an exposure with the outcome of interest.
What is the difference between confounding and effect modification?
In short, confounders distort the association between the predictor and outcome, while effect modifiers differentiate the association between the predictor and outcome. One should adjust for confounders, but report the different effects seen for effect modifers.
What is effect modification in epidemiology?
Effect modification occurs when the magnitude of the effect of the primary exposure on an outcome (i.e., the association) differs depending on the level of a third variable. Unlike confounding, effect modification is a biological phenomenon in which the exposure has a different impact in different circumstances.
How do you identify effect modification?
To check for effect modification, conduct a stratified analysis. If the stratum-specific measures of association are different than each other and the crude lies between them, then it’s likely that the variable in question is acting as an effect modifier.
What is the major difference between confounding and interaction?
With confounding variables, you can often leave one or the other out and get a more accurate model (although not always). With an interaction, leaving one or the other out will likely make it worse.
What is the difference between effect modification and interaction?
Interaction is defined in terms of the effects of 2 interventions whereas effect modification is defined in terms of the effect of one intervention varying across strata of a second variable. Often the terms interaction and effect modification are used interchangeably.
