Collecting Data
Collecting data covers the practical methods used to gather information for a statistical investigation, including surveys and questionnaires, observation, experiments, and using data that already exists (secondary data). The method chosen depends on the type of data needed, the population being studied, and practical factors like time and cost. GCSE Statistics exams often ask you to identify a suitable method or to critique a data collection method used in a given scenario.
Method
- Decide what data you need (its type, and whether primary or secondary data is appropriate) before choosing a method.
- For primary data, choose between a questionnaire/survey (asking people directly), an experiment (controlling variables to test something), or observation (recording what happens without intervening).
- For secondary data, identify a reliable existing source, such as government statistics or published research, and check it is relevant and up to date.
- Consider practical factors: cost, time available, and how easy the data is to access, since these can limit which method is realistic.
- Check the method for possible sources of bias, such as leading questions, a non-random sample, or observer effects.
- Pilot the method on a small group first if possible, to catch problems before collecting the full data set.
Worked example
A student is investigating whether it rains more in the north of the UK than the south. Suggest a suitable method of collecting the data she needs, and explain your choice.
- Identify the data needed: rainfall amounts (in mm) for locations in the north and south of the UK over the same time period.
- Consider primary data collection: setting up rain gauges herself in several towns would take a long time and be hard to do accurately across a whole country.
- Consider secondary data: the Met Office already publishes reliable rainfall records for towns across the UK.
- Choose secondary data, since it is already collected accurately over a long period and covers far more locations than she could measure herself.
- Final answer: use secondary data (existing published rainfall records), because it is more reliable, wide-reaching and practical than collecting primary data herself.
Practice questions
Type your answer and press Check to be marked straight away, or reveal the answer and mark yourself.
Q1State whether interviewing shoppers face-to-face about their favourite supermarket is primary or secondary data collection.Show answer
Answer: Primary (the researcher collects it first-hand)
Q2A student uses figures from a government website for her project. Is this primary or secondary data?Show answer
Answer: Secondary (it already existed before her investigation)
Q3Give one advantage of using a questionnaire to collect data.Show answer
Answer: It can reach a large number of people relatively cheaply and quickly (accept any valid advantage)
Q4Give one disadvantage of an observation study.Show answer
Answer: People may behave differently when they know they are being watched (observer effect), or it can be time-consuming (accept any valid disadvantage)
Q5A question asks: 'Don't you agree that the new bus timetable is an improvement?' State what is wrong with this question.Show answer
Answer: It is a leading question, which encourages a particular (biased) answer
Q6State one advantage secondary data has over primary data for a project on rainfall over the last 50 years.Show answer
Answer: It already exists over that time period, so the researcher does not need to have been collecting it for 50 years themselves
Exam-style questions
Written in the style of a GCSE Statistics exam paper, with a full mark scheme.
A researcher wants to find out how long people spend commuting to work. State one primary method she could use to collect this data, and one advantage of that method.
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A gym wants to know how satisfied its members are. It leaves a box of comment cards at the reception desk. (a) State one problem with this method of data collection. (b) Suggest a better method. (c) Give one reason your suggested method is better.
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A scientist wants to test whether a new fertiliser increases the height of tomato plants. (a) State the type of data collection method most suitable (survey, observation, or experiment). (b) Explain your choice. (c) State one variable she should keep the same between the group given fertiliser and the group not given fertiliser.
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See real GCSE Statistics past-paper questions, with official mark schemes →
Free printable worksheet
Want more practice on paper? Download the collecting data worksheet pack - 13 pages of exam-style questions with a full mark scheme. One email opens every download in this browser for 14 days - no account, no card. Print it for personal and classroom use.
This topic is chapter 8 of GCSE Statistics Foundation Workbook 1 and chapter 8 of GCSE Statistics Higher Workbook 1, the whole course as one free printable PDF.
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