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1.3.4Unit 1: Lifestyle, Transport, Genes and Health

Interpreting Data on Risk Factors — IAL Edexcel Linear Revision Notes & Topical Questions

5 min read 5 parts Lesson 22 of 29 Unit quiz

📚 IAL Edexcel Linear Hub / Topical Revision
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Curriculum Equation Key قوانين الرقم الهيدروجيني والاتزان الأيوني - pH & Acid-Base Equilibrium FormulasFast Exam Solution
pH = -log[H⁺] | pOH = -log[OH⁻] | pH + pOH = 14 | [H⁺][OH⁻] = 10⁻¹⁴
Word Equation & Conditions: الرقم الهيدروجيني = -لوغاريتم تركيز أيون الهيدروجين | pH + pOH = 14
Location & Specifications: الاتزان الأيوني، كيمياء 3 ثانوي، التحصيلي، و AP Chemistry.
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Part 1 of 5Reading the Data

Describe
  • Describe State the trend and support it with figures from the data, quoting the highest and lowest values and any units.
Conclude
  • Conclude State what the data show, such as an association between two variables, without going further than the evidence.
Correlation and cause
  • Correlation and cause A relationship between two variables does not prove that one causes the other, as a third factor may influence both.
Extrapolation
  • Extrapolation Conclusions should be limited to the groups and conditions studied, not applied to people outside the sample.

Part 2 of 5Evaluating the Quality

Evaluating the Quality
Sample size
  • Sample size A large sample is more likely to be representative of the population and reduces the effect of chance.
Control of variables
  • Control of variables Factors such as age, sex and diet should be matched or accounted for so that only the risk factor differs.
Statistics
  • Statistics A statistical test shows whether a difference is significant or could have arisen by chance.
Bias
  • Bias The source of funding and the way participants were selected can bias results, so independent repeated studies are valued.

Part 3 of 5Calculating Risk

1
Absolute risk is the proportion of a group that develops the disease, such as 12 cases per 1000 people.
2
Relative risk is the risk in the exposed group divided by the risk in the unexposed group.
3
A relative risk of 1 means no difference, a value above 1 shows increased risk and below 1 shows reduced risk.
4
Percentage change is (new value − original value) ÷ original value × 100, and is used to compare changes in risk.
5
Always give the answer with a sensible number of significant figures and the correct units or label.

Part 4 of 5Worked Example

Question

  • In a study, 18 out of 1000 smokers and 12 out of 1000 non-smokers developed CVD.
  • Calculate the relative risk for smokers and the percentage increase in risk.

  1. Risk in smokers = 18 ÷ 1000 = 0.018; risk in non-smokers = 12 ÷ 1000 = 0.012.
  2. Relative risk = 0.018 ÷ 0.012 = 1.5.
  3. Percentage increase = (0.018 − 0.012) ÷ 0.012 × 100 = 50%.

Answer The relative risk is 1.5, a 50% increase in the risk for smokers.

Part 5 of 5Exam Checklist & Tips

1.3.4 – Key Points for the Exam

  • Relative risk The risk in an exposed group divided by the risk in an unexposed group.
  • Correlation A statistical association between two variables.
  • Causation A relationship in which one variable directly produces a change in another.
  • Representative sample A sample that reflects the make-up of the whole population.

Common Mistakes

  • Concluding that a risk factor causes disease from a single correlation.
  • Quoting figures from the data in a description but forgetting to include units or the trend.
  • Dividing by the wrong value when calculating relative risk or percentage change.
  • Applying conclusions from one age group to a very different one.

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