Confounding

Question 1

What does confounding mean?

Answer 1

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

Question 2

How can confounding be controlled when designing an experiment?

Answer 2

It can be controlled by randomisation

(It aims to produce an even amount of risk factors in each population)

Question 3

How can confounding be controlled in the analysis stage of an experiment?

Answer 3

By Stratification

Stratification can be used to ensure equal allocation of subgroups of participants to each experimental condition. This may be done by gender, age, or other demographic factors.

Question 4

What are the common causes of confounding in studies?

Answer 4

Age, sex and social class

Question 5

Give an example of confounding using colorectal cancer, aspirin and age?

Answer 5

• A case-control study looks at whether low-dose aspirin can prevent colorectal cancer
• The proportion of people diagnosed with colorectal who took aspirin is compared to the proportion of people without colorectal cancer who took aspirin
• If the case and control groups are not matched for age then age could be said to be a confounding factor as older people are more likely to take aspirin and also more likely to develop cancer