Fieldwork: collecting data

Primary and secondary data

is data you collect yourself, in the field: measurements, counts, surveys and photos.
is data someone else has collected: census figures, maps, flood records, websites and books.

Quantitative data is numbers, such as velocity or traffic counts. Qualitative data is words, opinions and images, such as interviews or annotated photos.

Most enquiries use both primary and secondary data, so you can compare your results with others.

Key terms

Methods: two worked examples

Written for this app.

Physical: river velocity. At eight sites, 1 km apart, along an invented river:

Measure 10 m along the bank.
Drop a float, such as an orange, in the middle of the channel, and time it over the 10 m.
Repeat three times and find the time.
Velocity = distance ÷ time.

Human: environmental quality. At 22 sites across an invented town:

Score ten things, such as litter, noise, traffic and green space, from 1 (poor) to 5 (good), to give a total out of 50: an .
Take a photo at each site.

Use the same method at every site, so results can be compared.

Key terms

Sampling

You can't measure everywhere, so you take a sample.

Type	How	Why
Random	Sites chosen by chance, e.g. random numbers for grid references	Avoids bias
Systematic	Sites at regular intervals, e.g. every 1 km along a river	Covers the whole area evenly
Stratified	Sites in proportion to sub-groups, e.g. more sites in the larger zone	Makes sure every group is fairly represented

The river enquiry used systematic sampling, to show change downstream. The town enquiry used stratified sampling: 11 sites in each of two zones, inner and outer.

Exam tip

Justify a method: say what you did, and why it suited your hypothesis.

Key terms

Exam practice

Plan your own answer first, then open the model answers to see what each level looks like.

6 marks · about 6 minutes

For one of your fieldwork enquiries, justify your sampling strategy.

Justify means: Give reasons and evidence to support a choice or a decision.

Level 1 (Basic)· 2/6 marks (band 1–2)

We used systematic sampling. We picked sites along the river.

Why this level: Names the strategy but doesn't justify it. To reach Level 2: say how sites were chosen and why this suited the hypothesis. In the exam, use the details of your own enquiry.

Level 2 (Clear)· 4/6 marks (band 3–4)

We used systematic sampling, with eight sites 1 km apart along the river. This suited our hypothesis, "River velocity increases downstream", because evenly spaced sites covered the whole stretch of river, so we could see how velocity changed with distance.

Why this level: Clear justification linked to the hypothesis. To reach Level 3: compare with another strategy and include a limitation. In the exam, use the details of your own enquiry.

Level 3 (Detailed)· 6/6 marks (band 5–6)

We used systematic sampling, with eight sites 1 km apart along the river. This suited our hypothesis, "River velocity increases downstream", because evenly spaced sites covered the whole stretch, so any change in velocity with distance would show clearly. It also made the sampling fair, as we didn't choose sites that might give the result we expected. Random sampling might have bunched sites together and missed parts of the river, which would have made the pattern harder to see. However, systematic sampling has a weakness: one site fell in a deep pool, which gave an unusually low velocity. Moving the site slightly to a typical stretch of river would have avoided this.

Why this level: A detailed justification linked to the hypothesis, compared with an alternative, with a limitation and an improvement. This is Level 3. In the exam, use the details of your own enquiry.

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