Confounding

Question 1

What is confounding? Give an example

Answer 1

confounding refers to a variable which correlates with other variables within a study leading to spurious results.

E.g. A study finds that people who drink coffee are more likely to develop heart disease.
The confounding factor in this study is smoking. Smoking is associated with both drinking coffee and heart disease. People who drink coffee are also more likely to smoke.

Question 2

When does confounding most commonly occur

Answer 2

When there is a non random distribution of risk factors in the populations.

Question 3

give examples of common causes of confounding in studies

Answer 3

Age, sex and social class are common causes of confounding.

Question 4

Describe how confounding can be minimised at different stages of a study

Answer 4

Design stage - controlled by randomisation which aims to produce an even amount of potential risk factors in two populations.

Analysis stage - controlled for by stratification.