Confounding bias: A systematic distortion in the measure of association between exposure and the health outcome caused by mixing the effect of the exposure of primary interest with extraneous risk factors.
What does confounding mean in research?
What is confounding? Confounding is often referred to as a “ mixing of effects ” 1 , 2 wherein the effects of the exposure under study on a given outcome are mixed in with the effects of an additional factor (or set of factors) resulting in a distortion of the true relationship.
What is confounding and selection bias?
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 ...
How do you get rid of confounding bias?
- randomization (aim is random distribution of confounders between study groups)
- restriction (restrict entry to study of individuals with confounding factors – risks bias in itself)
- matching (of individuals or groups, aim for equal distribution of confounders)
What is the concept of confounding?
Confounding is a distortion (inaccuracy) in the estimated measure of association that occurs when the primary exposure of interest is mixed up with some other factor that is associated with the outcome . ... Or, if the age distribution is similar in the exposure groups being compared, then age will not cause confounding.
Can confounding cause bias?
Confounding is one type of systematic error that can occur in epidemiologic studies. ... Confounding is also a form a bias. Confounding is a bias because it can result in a distortion in the measure of association between an exposure and health outcome .
What are confounding variables?
Confounding variables are those that affect other variables in a way that produces spurious or distorted associations between two variables . They confound the “true” relationship between two variables.
What are examples of confounding variables?
For example, the use of placebos, or random assignment to groups. So you really can’t say for sure whether lack of exercise leads to weight gain. One confounding variable is how much people eat . It’s also possible that men eat more than women; this could also make sex a confounding variable.
Is age a confounding variable?
Age is a confounding factor because it is associated with the exposure (meaning that older people are more likely to be inactive), and it is also associated with the outcome (because older people are at greater risk of developing heart disease).
Is time a confounding variable?
Here, we consider “time-modified confounding,” which occurs when there is a time-fixed or time-varying cause of disease that also affects subsequent treatment, but where the effect of this confounder on either the treatment or outcome changes over time.
How do you fix a confounding variable?
There are several methods you can use to decrease the impact of confounding variables on your research: restriction, matching, statistical control and randomization . In restriction, you restrict your sample by only including certain subjects that have the same values of potential confounding variables.
Can confounding variables be controlled?
A Confounder is a variable whose presence affects the variables being studied so that the results do not reflect the actual relationship. There are various ways to exclude or control confounding variables including Randomization, Restriction and Matching .
Why are confounding variables bad?
Confounding variables are common in research and can affect the outcome of your study. This is because the external influence from the confounding variable or third factor can ruin your research outcome and produce useless results by suggesting a non-existent connection between variables .
Why is gender a confounding variable?
Hence, due to the relation between age and gender, stratification by age resulted in an uneven distribution of gender among the exposure groups within age strata . As a result, gender is likely to be considered a confounding variable within strata of young and old subjects.
What is confounding variable in psychology?
in an experiment, an independent variable that is conceptually distinct but empirically inseparable from one or more other independent variables. Confounding makes it impossible to differentiate that variable’s effects in isolation from its effects in conjunction with other variables. ... Also called confounding variable.
What is the difference between confounding and extraneous variables?
Extraneous variables are those that produce an association between two variables that are not causally related. Confounding variables are similar to extraneous variables, the difference being that they are affecting two variables that are not spuriously related . ...
