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Fieldwork » Collecting Fieldwork Data

What you'll learn this session

Study time: 30 minutes

AQA spec: 3.3.2

Choose the right physical and human data for an enquiry
Use random, systematic and stratified sampling
Measure and record data using suitable methods
Describe and justify the methods you used

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Enquiry strand 2: selecting, measuring and recording data

Measuring and recording data carefully is key to good fieldwork

Once you have a question or hypothesis, you need data to answer it. AQA calls this strand 2: selecting, measuring and recording data appropriate to your enquiry. You must pick data that really tests your question, collect it in a sensible way and write it down accurately.

Remember, primary data is collected first-hand by you in the field. Secondary data was collected by someone else, such as a census, a weather report or an old map. Every enquiry must include primary data. Secondary data is useful for extra background and for comparing with your own results.

Selecting physical and human data

Your choice of data depends on the question. Physical enquiries need data about the natural environment. Human enquiries need data about people and the places they build. Some enquiries need both.

🏖 Physical data

Beach pebble size, beach gradient, wave height, soil depth, or the plants growing at different points on a sand dune. Secondary physical data could be tide tables or rainfall records.

🏙 Human data

Traffic counts, answers to a questionnaire, shop types on a high street, or an environmental quality score. Secondary human data could be census figures or house price records.

Choose data that is appropriate. If your question is about how pebbles change along a beach, then measuring pebble size is appropriate. Counting the visitors would not help at all.

Why we sample

You cannot measure every pebble on a beach or ask every person in a town. So you collect a sample: a smaller set of measurements chosen to represent the whole area or population. Sampling is the way you choose which measurements to take. A bigger sample is more likely to give a fair picture, but it takes more time. A good sample is large enough to be useful and small enough to collect in the time you have.

Three sampling methods

🎲 Random

Every item has an equal chance of being chosen. You might use random numbers from a calculator to pick the spots, so you cannot choose your favourites. This avoids bias, which is when the results lean towards one result because of how the sample was picked. It can miss parts of the area by chance.

📏 Systematic

You sample at regular intervals, for example every 10 metres along a line. It is quick, easy and covers the whole area evenly. It could miss a pattern that repeats at the same spacing.

📊 Stratified

You split the population into groups, then sample each group in proportion to its size. It makes sure every group is fairly represented. It needs more planning and you must know the size of each group first.

Key terms:

Sample: a smaller set of data taken to represent the whole
Random sampling: choosing items by chance so each has an equal chance
Systematic sampling: choosing items at regular intervals
Stratified sampling: sampling each group in proportion to its size
Bias: results that are unfairly pushed one way by how the data was collected

Worked example

You want to ask 40 people about a seaside town. Of the people you can meet, 60% are residents, 30% are day visitors and 10% are staying visitors. A stratified sample would ask 24 residents (60% of 40), 12 day visitors (30% of 40) and 4 staying visitors (10% of 40). The 40 answers now match the mix of people in the town.

Measuring and recording physical data

Physical data like river speed is measured with simple equipment

Different data needs different equipment. Always use the same method at every site so that results can be compared.

Pebble size: measure the longest axis of each pebble with a ruler or callipers (a tool with two arms that grips the pebble). Record the result in millimetres. Take about 10 to 20 pebbles at each site, using systematic or random sampling.
Beach gradient: two people hold ranging poles (tall marker poles) and read the angle with a clinometer (a tool that reads the angle of a slope). Record the angle in degrees at each point along a line.
Plant cover on a sand dune: place a quadrat (a square frame, often 1 m by 1 m) on the ground and estimate the percentage covered by plants. A transect is a straight line across the area, with a quadrat placed at regular intervals along it. This is systematic sampling.

Measuring and recording human data

Questionnaire: a set of questions asked to people. Keep questions short, clear and neutral. Closed questions with a tick box are quick to record and easy to count. Ask a mix of ages and do not only stop people who look friendly, or you add bias.
Traffic or pedestrian count: use a tally chart and count for the same length of time, such as 5 minutes, at each site.
Environmental quality survey: score features such as litter, noise, graffiti and building condition, often from -2 to +2. Add the scores to get a total for each site.

Write down every result clearly, with the site, the time, the date and the units. Write neatly and double-check each number before you move on. Taking a photo or a field sketch can also help you remember the site later.

Describing and justifying your methods

In the exam you must be able to describe a method (say exactly what you did, step by step) and justify it (say why it was the best choice). A good justification links the method to the question, the type of data and the sampling choice.

✎ Describe

"We placed a 1 m quadrat every 10 metres along a transect from the beach to the back of the dune. We estimated the percentage plant cover and recorded it."

✅ Justify

"Regular intervals covered the whole dune evenly, so we could see how plant cover changed with distance from the sea. A quadrat gave the same sized area each time, so the results could be compared fairly."

Common mistakes

Students say "we took a random sample" when they actually chose spots by eye. Others only describe what they did and forget to say why. Another mistake is to use different methods or different times at each site, which makes the results unfair to compare.

Exam-style question

A group of students investigated how the size of pebbles changes along a beach. They collected primary data at five sites.

(a) Name one piece of equipment they could use to measure pebble size. [1 mark]

(b) The students used systematic sampling to choose their sites. Describe how they could do this. [2 marks]

Model answer

(a) A ruler or callipers (1).

(b) They would choose sites at regular intervals along the beach, such as every 20 metres (1). They would start at one end and measure at each interval until the other end (1).

(c) Sites at regular intervals cover the whole beach evenly (1), so the students could see how pebble size changes along the beach and compare the sites fairly (1).

Exam tip

In a "justify" question, always give a reason that links back to the enquiry question, such as "so they could see how size changed along the beach".

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