a particular type of extraneous variable which for some reason has been left uncontrolled
a variable the experimenter did not take into consideration and which could account for the observed relationship between the independent and dependent variables
a variable which has an unintentional effect on the dependent variable
An unforeseen, and unaccounted-for variable that jeopardizes reliability and validity of an experiment's outcome.
Confounder: A variable that can cause or prevent the outcome of interest, is not an intermediate variable, and is associated with the factor under investigation. A confounding variable may be due chance or bias. Unless it is possible to adjust for confounding variables, their effects cannot be distinguished from those of factor(s) being studied. ( Harm, Therapy).
A variable that effects the outcome of interest but is not related to the factor under investigation. For example, going to cardiac rehabilitation after a heart attack decreases your chances of dying of heart disease but this result is confounded by the fact that people who look after themselves generally are more likely to go to rehabilitation and less likely to die of heart disease.
or confusing factor - A factor or variable in the subjects being studied that introduces error or skews the results of the study.
Something that can obscure or interfere with the cause and effect relationship being observed in an experiment. In an experiment it is desirable for there to be only one difference between two groups on the independent variable. However, if one group is affected by something other than the independent variable (such as a sudden outside noise or by a different instruction) but not the other group then this is a confounding variable. This confound could either improve or just change the behaviour of one group and hence could be the cause of differences in behaviour rather than the independent variable.
A variable more likely be present in one group of subjects than another that is related to the outcome of interest and thus potentially confuses, or "confounds," the results.
a variable that, within a specific epidemiological study, is associated both with the disease of interest and with the exposure of interest, thus distorting the relationship. An example is that age is related both to smoking history and to risk of lung cancer and thus must be accounted for (controlled) in studies of smoking as a cause of lung cancer.
