Questionnaires, Data Cleaning and Controls
Design neutral questions and response sections, resolve unusable records and understand extraneous variables and controls.
How to study for GCSE Statistics
Practise complete statistical enquiries: define the question, obtain suitable data, represent and analyse it, interpret in context, evaluate limitations and refine the method.
Core concepts
Concept 1
Open and closed questions serve different purposes and require unambiguous wording and response options.
Exam cue: Test wording and response categories, define a defensible cleaning rule and record rather than hide changes.
Concept 2
Cleaning addresses missing, inconsistent, incorrectly formatted or extraneous data before analysis.
Exam cue: Make response categories exhaustive and non-overlapping where one response is required.
Concept 3
Extraneous variables can offer alternative explanations for observed differences.
Exam cue: State the population, variables, context and purpose before choosing or interpreting a statistical technique.
Targeted study blocks
Tier coverage
Foundation core with Higher-tier extensions
Higher-only content adds the use of control groups. Foundation and Higher both address cleaning and the importance of controlling extraneous variables.
Risk pitfalls and guardrails
Deleting inconvenient values without a stated rule or audit trail.
Guardrail: Do not turn statistical reasoning into an unexplained calculation or generalise beyond the population and design supported by the data.
Reporting a calculation without interpreting it in the context of the investigation.
Guardrail: Do not turn statistical reasoning into an unexplained calculation or generalise beyond the population and design supported by the data.
Assuming the other board's paper duration, wording or formula presentation applies.
Guardrail: Check the live board specification and assessment-series materials before final revision or timed practice; never infer a current paper rule from an old paper.
Memory anchors
Leading question
Wording that encourages a particular response.
Data cleaning
Identifying and resolving unusable or inconsistent records.
Extraneous variable
An uncontrolled factor that may affect the response.
Questionnaires, Data Cleaning and Controls: method
Test wording and response categories, define a defensible cleaning rule and record rather than hide changes.
Questionnaires, Data Cleaning and Controls: check
Make response categories exhaustive and non-overlapping where one response is required.
Checkpoint rule
Do the check-up only after you can summarize each concept in one sentence and identify one dangerous pitfall from memory.
Knowledge Check (after reading)
Short check-up to confirm understanding of this module.
Check-up Questions
Which questionnaire item is unambiguous?
What is the main weakness of “Was the lesson clear and enjoyable?”
Answer all questions to submit.
Next step personalized recommendations
Continue learning
Move forward only after this module is stable.
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