Social Research Glossary


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Citation reference: Harvey, L., 2012-20, Social Research Glossary, Quality Research International,

This is a dynamic glossary and the author would welcome any e-mail suggestions for additions or amendments. Page updated 19 December, 2019 , © Lee Harvey 2012–2020.


A fast-paced novel of conjecture and surprises


Confounded variable

core definition

Two variables are said to be confounded if they vary with each other in a systematic way so that it is difficult to tell which of the two is affecting some third variable.

explanatory context

For example, height and weight are larely confounded. There would not be many tall lightweights or short heavyweights and this would make it difficult to sort out their effects unequivocally on a third variable such as boxing ability.


see QRT

analytical review

Colorado State University (1993–2013) defines confounding variable as:

An unforeseen, and unaccounted-for variable that jeopardizes reliability and validity of an experiment's outcome.


The NHS Health News Glossary, (NHS, undated) refers to a confounding factor:

Confounding factor (confounder): A confounder can distort the true relationship between two (or more) characteristics. When it isn't taken into account, false conclusions can be drawn about associations. An example is to conclude that if people who carry a lighter are more likely to develop lung cancer, it's because carrying a lighter causes lung cancer. In fact, smoking is a confounder here. People who carry a lighter are more likely to be smokers, and smokers are more likely to develop lung cancer.


associated issues


related areas

See also


multivariate analysis



Colorado State University, 1993–2013, Glossary of Key Terms available at, accessed 3 February 2013, still available 1 June 2019.

NHS, undated, Health News Glossary, available at, accessed 1 June 2019.

copyright Lee Harvey 2012–2020


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