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The collection of data

5 dot points across 5 inquiry questions. Click any dot point for a focused answer with worked past exam questions where available.

How do you collect reliable, valid data and design questions that are not biased?

Sources of data, reliability and validity, designing questionnaires and data collection sheets, open and closed questions, leading questions, pilots, and cleaning data before processing.
A focused answer to Edexcel GCSE Statistics on collecting data and designing questionnaires, covering data sources, reliability and validity, open and closed questions, designing non-overlapping response boxes, spotting leading questions, pilots, and cleaning data before processing.
9 min answer →

How do you control variables and remove bias so an experiment is a fair test?

Identifying and controlling extraneous variables, control groups and matched pairs, sources of bias, sensitivity of content, and the random response technique for sensitive questions.
A focused answer to Edexcel GCSE Statistics on controlling variables and bias, covering explanatory and extraneous variables, control groups and matched pairs, sources of bias, sensitivity of content, and the random response technique for sensitive questions at Higher tier.
9 min answer →

How do you choose a sampling method that represents the population without bias?

Population, sampling frame and sample; simple random, systematic, stratified, quota, cluster, judgement and opportunity sampling; selecting random members; calculating strata sizes.
A focused answer to Edexcel GCSE Statistics on sampling, covering population, sampling frame and sample, simple random, systematic, stratified, quota, cluster, judgement and opportunity sampling, selecting random members electronically, and calculating stratified sample sizes.
10 min answer →

How does the statistical enquiry cycle turn a question into a sound conclusion?

The statistical enquiry cycle: planning a hypothesis, recognising constraints, collecting, processing, interpreting and evaluating, with proactive strategies to manage problems.
A focused answer to Edexcel GCSE Statistics on the statistical enquiry cycle, covering the five stages, writing a testable hypothesis, recognising constraints such as time, cost and ethics, and planning proactive strategies to handle problems like non-response.
9 min answer →

How do you classify data, and why does the type decide what you can do with it?

Types of data: raw, quantitative, qualitative, categorical, ordinal, discrete, continuous, ungrouped, grouped, bivariate and multivariate; primary versus secondary; explanatory and response variables; grouping into class intervals.
A focused answer to Edexcel GCSE Statistics on types of data, covering quantitative versus qualitative, categorical and ordinal, discrete and continuous, grouped and bivariate data, primary versus secondary sources, explanatory and response variables, and the effect of grouping into class intervals.
9 min answer →