IGCSE Geography / Fieldwork - the enquiry process
Sampling and risk assessment revision notes
Edexcel International GCSE Geography (4GE1), chapter 10: Fieldwork - the enquiry process, specification point E3, G4, G7. Free lesson.
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Sampling uses a small part of a whole area or population to represent it. A suitable sample and a clear risk assessment help make fieldwork results useful and safe.
What a sample does
A sample is a small part of a whole, measured or asked so it can stand for all of it. A representative sample gives a fair picture of the whole. Bias is anything that makes a sample unfair. Sampling is part of enquiry design: it decides where to collect data or who to ask, not how to measure. You sample because there is not enough time to measure every pebble or ask every person.
How the three sampling methods work
Each method can choose sites or people. A transect is a line across the study area. Match the method to the enquiry because each has strengths and weaknesses. Systematic sampling uses equal intervals, such as one site every 50 m along a beach or every tenth person who passes. It covers an area evenly, and you do not choose the sites, but it can miss features between intervals. It suits change along a line, such as a river or transect. Random sampling uses chance. Random numbers can select distances, grid squares or house numbers from a list. Each site or person has an equal…
How to calculate a stratified sample
Use the same proportion of each group as of the whole population. For 40 people from a village of 800, the share is 40 ÷ 800 = 0.05, or 1 in 20.
How sample size affects reliability
Sample size is the number of sites, readings or people included. A larger sample is more reliable, meaning you would get much the same result again. It is more likely to include different parts of the population, and one unusual answer has less effect. One odd answer is 20% of a sample of 5, but only 2% of a sample of 50. Five people can miss whole groups; 50 gives a picture closer to the whole population. The same applies to sites: 3 may not show a clear trend, while 8 can. Choose the largest sample the available time allows.
How to assess and score fieldwork risks
A hazard is anything that could cause harm. A risk assessment lists each hazard, who could be harmed, the possible harm and how to reduce it. One common score is likelihood × severity, each rated from 1 to 5. Deal with the highest score first. Traffic could hit a student: 2 × 5 = 10. Stay on the pavement and cross only at crossings. Wet, slippery rocks could cause a slip and sprained ankle: 4 × 2 = 8. Wear boots with grip; walk, never jump. Hot sun could cause sunburn: 3 × 1 = 3. Use a hat, sun cream and water. The risk is the possible harm, not the safety step.
How to explain a sampling choice
Explain what the method does to the sample. For systematic sampling, equal intervals cover the beach evenly and the student does not choose the sites, so there is less bias. “Quick and easy” is not enough because it could describe any method. Asking the first 40 people passing a town centre on Monday morning may leave out most people at work or school. A stratified sample asks each age group in proportion to its share of the population, so it represents all residents.