Students should be able to evaluate the positions of health advisers and…

The idea

Evaluation means weighing evidence and reaching a justified conclusion, not simply stating an opinion. Health advisers link the rising incidence of type II diabetes to rising obesity and to diets high in fat and sugar, and argue that reducing sugar in processed foods, clearer labelling, restrictions on advertising and taxes on sugary drinks would lower incidence. The food industry replies that such evidence is largely correlational, that individuals choose what they eat, that genetics, ethnicity, age and inactivity also contribute, and that reformulating products is costly. A strong answer uses any data supplied, distinguishes correlation from causation, and states what further evidence, such as a long-term human study, would help settle the question.

What earns the marks

• An argument supporting the health advisers' position that uses data or evidence supplied, for example linking a rise in sugar consumption or obesity to a rise in type II diabetes incidence.
• An argument supporting the food industry's position that uses data or evidence supplied, for example noting that many people with high sugar intake do not develop type II diabetes.
• An explicit statement that a correlation between diet and type II diabetes does not by itself establish causation, because other variables may be involved.
• A valid limitation of the evidence, such as the study being on animals rather than humans, too short to show long-term effects, or not controlling for genetics, age or inactivity.
• A justified conclusion that follows from the evidence discussed, for example that diet is likely to be one risk factor among several rather than the sole cause.
• Reference to at least one other risk factor for type II diabetes, such as genetics, ethnicity, age or inactivity, and an explanation of how it weakens a simple dietary explanation.

Common mistakes and how to put them right

• Writing an opinion piece that never refers to the data or evidence supplied.

  Put it right: Quote specific figures or findings from the table or graph in each paragraph.

• Giving only one side when the command word asks for an evaluation.

  Put it right: Structure the answer as for, against, therefore, covering both positions before concluding.

• Claiming that the data prove sugar causes type II diabetes.

  Put it right: State that the data show a correlation, and that correlation does not establish causation.

• Dismissing a whole study because the sample was small, without explaining why this matters.

  Put it right: Explain that a small sample may not be representative, so conclusions cannot be generalised.

• Confusing a risk factor with a cause in the conclusion.

  Put it right: Describe diet as a risk factor that increases probability, not as a proven cause.

Exam tips

• Structure the answer as for, against, therefore; ensure both sides are covered before writing the conclusion.
• Quote figures from the table or graph rather than describing the pattern in words alone, and say what each figure shows.
• State what further evidence would settle the question, such as a long-term controlled study on humans that accounts for genetics and lifestyle.