statistical skills and data analysis
4 detailed 50-minute lessons with teaching scripts, worked examples, parent guides, and assessment criteria.
4 detailed 50-minute lessons with teaching scripts, worked examples, parent guides, and assessment criteria.

Write down everything you already know about statistical skills and data analysis. Then check against the key terms: Common Error, Key Rule, Exam Technique. Use a mini-whiteboard or paper.
Start with the revision notes summary, then attempt: Calculate the mean, median, mode, and range for the following data: 12, 15, 18, 18, 22, 25, 30, 35
Your student states one thing they learned and one question they still have about statistical skills and data analysis.
Quick recap: write 3 key points from Lesson 1 on statistical skills and data analysis. Check them against the notes below.
| Term | Meaning | Example |
|---|---|---|
| Mean | When data has no extreme outliers; for further calculations | Average rainfall across a year; mean GNI per head for a region |
| Median | When data has outliers that would distort the mean | Typical house price in an area (a few mansions would distort the mean) |
| Mode | For categorical data; finding the most common value | Most common rock type; most frequent wind direction |
| Where | Within the data range | Outside the data range |
| Reliability | Generally reliable | Less reliable - trend may change |
| Assumption | Trend between known points continues | Trend continues beyond known data |
| Risk | Low - supported by surrounding data | High - no data to verify the estimate |
| Calculate the mean/median/mode | Show your working; arrange data in order for median; identify the most frequent for mode |
Q: Calculate the mean, median, mode, and range for the following data: 12, 15, 18, 18, 22, 25, 30, 35
Answer: Mean = (12+15+18+18+22+25+30+35) ÷ 8 = 175 ÷ 8 = 21.875 ≈ 21.9. Median = (18+22) ÷ 2 = 20 (middle two of 8 values). Mode = 18 (appears twice, all others appear once). Range = 35 − 12 = 23.
Your student teaches the key points back to you without looking. Fill any gaps immediately.
Recall the key terms: Common Error, Key Rule, Exam Technique. Define each in one sentence.
Q1: Calculate the mean, median, mode, and range for the following data: 12, 15, 18, 18, 22, 25, 30, 35
Answer: Mean = (12+15+18+18+22+25+30+35) ÷ 8 = 175 ÷ 8 = 21.875 ≈ 21.9. Median = (18+22) ÷ 2 = 20 (middle two of 8 values). Mode = 18 (appears twice, all others appear once). Range = 35 − 12 = 23.
Q2: A country's exports were $4.2 billion in 2015 and $6.3 billion in 2025. Calculate the percentage change.
Answer: Percentage change = ((6.3 − 4.2) ÷ 4.2) × 100 = (2.1 ÷ 4.2) × 100 = 0.5 × 100 = 50% increase.
Q3: Explain the difference between the range and the interquartile range. Why is the IQR often preferred?
Answer: The range is the difference between the highest and lowest values, using only two data points. The IQR is the difference between Q3 and Q1, measuring the spread of the middle 50% of data. The IQR is preferred because it ignores the most extreme values (the top 25% and bottom 25%) that may be outliers, giving a better representation of typical variation. For example, if one house in an area costs £5 million while others are £150,000-£300,000, the range would be huge but the IQR would still reflect typical variation.
Q4: What is the difference between interpolation and extrapolation? Which is more reliable and why?
Answer: Interpolation estimates a value within the existing data range by reading off the line of best fit. Extrapolation estimates a value beyond the data range by extending the line of best fit. Interpolation is more reliable because it is supported by observed data on either side of the estimate. Extrapolation is less reliable because it assumes the trend continues in the same way beyond the data, which may not be true (e.g. a population growth trend may flatten off).
Q5: Explain what is meant by "correlation does not prove causation" with a geographical example.
Answer: "Correlation does not prove causation" means that just because two variables are statistically related, it does not mean one causes the other. There may be a third underlying factor affecting both. For example, there is a positive correlation between a country's GNI per head and life expectancy, but higher GNI does not directly cause longer life - instead, higher GNI enables better healthcare, nutrition, and sanitation, which cause improved health. The correlation identifies a relationship, but understanding the mechanism requires geographical knowledge.
Q6: Using the following data, calculate Q1, Q3, and the IQR: 5, 8, 11, 14, 17, 20, 23, 26, 29, 32, 50
Answer: 11 values arranged: 5, 8, 11, 14, 17, 20, 23, 26, 29, 32, 50. Median = 20 (6th value). Lower half: 5, 8, 11, 14, 17 → Q1 = 11. Upper half: 23, 26, 29, 32, 50 → Q3 = 29. IQR = Q3 − Q1 = 29 − 11 = 18. Note: the range is 50 − 5 = 45, but the IQR of 18 better represents the typical spread because the outlier of 50 inflates the range.
Review any questions answered incorrectly. Identify whether the error was knowledge, method, or reading the question.
Review what these command words require: state (one point), describe (say what happens), explain (say why), compare (both sides), evaluate (judgement).
Attempt a past-paper style question on statistical skills and data analysis from the exam board past paper finder (see Resources), then mark it against the scheme.
You are ready for statistical skills and data analysis - GCSE Geography Lessons when you can:
Tick each item honestly — if any box is unticked, re-read the relevant section above.
How examiners mark statistical skills and data analysis - GCSE Geography Lessons: Read the command word carefully — State = one word/phrase (1 mark), Describe = pattern or detail (2 marks), Explain = reason with "because" (2–3 marks), Compare = similarities AND differences, Evaluate = both sides + conclusion. Method marks are awarded for correct working even if the final answer is wrong. Always show your working — unexplained answers score zero for AO2.
Success on statistical skills and data analysis - GCSE Geography Lessons questions: Underline the command word, count the marks (one mark per point expected), and answer in the format the command word demands.
This lesson is examined by: AQA 8035 | Edexcel 1GB0 | OCR J384 | Eduqas A/B | CCEA units. Tier and paper details vary - always check your board's current specification.
Follow-up revision: G48-statistical-skills on GCSE Revise (notes, flashcards and auto-graded target tests for this exact topic).