Risk factors are linked to an increased rate of a disease.

The idea

A risk factor is anything associated with a higher chance of developing a disease. Risk factors do not guarantee disease; they increase the rate at which it occurs in a population. Some risk factors are lifestyle choices, such as smoking, poor diet, alcohol use and lack of exercise. Others are not directly chosen, such as age, genetics or exposure to radiation. Scientists identify risk factors by comparing disease rates in groups with and without the factor. For example, if lung cancer is much more common among smokers than non-smokers, smoking is a risk factor. A causal link is stronger when evidence shows a mechanism, a dose response and consistency across studies.

What earns the marks

• Defines a risk factor as something linked to an increased rate or chance of disease.
• Distinguishes risk factors from causes: they raise probability, not certainty.
• Gives examples including lifestyle factors such as smoking, diet and alcohol, and non-lifestyle factors such as age or genetics.
• Explains how risk factors are identified by comparing disease rates between groups.
• Uses the term rate correctly, referring to occurrence in a population over time.

Common mistakes and how to put them right

• Saying a risk factor always causes the disease.

  Put it right: State that it increases the chance or rate.

• Treating correlation as proof of causation.

  Put it right: Require evidence such as a mechanism or dose response.

• Listing only lifestyle factors.

  Put it right: Include non-lifestyle factors such as age and genetics.

Exam tips

• Use the phrase increased rate or increased chance when defining risk factors.
• Support each risk factor with a named disease and a brief comparison of rates.
• Mention that other factors may contribute, showing balanced scientific reasoning.