What is a confounding factor? Epidemiological studies search for
the causes of diseases, based on associations with various risk
factors that are measured in the study. In addition to the
exposures that the study is investigating, there may be other
factors that is associated with the exposure and independently
affects the risk of developing the disease. If the prevalence of
these other factors differ between groups being compared, they
will distort the observed association between the disease and
exposure under study. These distorting factors are called
confounding factors or variables. A hypothetical example would
be a study of coffee drinking and lung cancer. If coffee
drinkers were also more likely to be cigarette smokers, and the
study measured coffee drinking but not smoking, the results may
seem to show that coffee drinking increases the risk of lung
cancer, which may not be true. However, if a confounding factor
(in this example, smoking) is recognized, adjustments can be
made in the study design or d